Popular in Course
Popular in Department
This 180 page Reader was uploaded by Clean Copy Inc. on Tuesday July 30, 2013. The Reader belongs to a course at Portland State University taught by a professor in Fall. Since its upload, it has received 753 views.
Reviews for G 301
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 07/30/13
PBW1 300lCOO4170 We assure mmpiiamre with 135 Gmvemmenf copyright iaw Permissim R3 dupiica ze any matariais vemd by cmpyr ght law has been secured GEOLOGY 301 WINTER QUARTER 2013 GEOLOGY FOR ENGINEERS 1 Professor Dr Scott Burns 2 Office Cramer Hall 17R 3 Telephone 7253389 email burnsspdxedu 4 Office Hours MWF 9001100 AM and by appt 5 Course Time MWF 800900 AM Cramer Hall 53 CRN 41445 SEC 002 6 Catalog Description Study of the origin interior and crustal materials of the earth the natural processes which have built it up deformed and torn down the crust throughout geologic time the environmental relationships between humans and geologic processes and resources stressing application to engineering For majors in civil engineering primarily but perfect course for environmental science planning and architecture majors and other disciplines of an applied nature Strong emphasis on geotechnology and the environment 3 credit hours 7 Book for the Course Allan Kehew Geology for Engineers and Environmental Scientists 3rd edition Prentice Hall 8 Activities Classroom lectures PowerPoint presentations and extra field trip 9 Grades Exam 1 30 Exam 2 30 Exam 3 40 10 Important Dates lst Exam Wednesday Jan 30 2013 2nd Exam Friday Feb 22 2013 Final Exam Monday Mar 18 2013 810 AM 11 Extra Credit There will be videos on geology on reserve in the library checkout from the reserve desk and watch in the viewing room After viewing a video write a onepage summary on it and turn it in for 5 points of extra credit added on to an exam Five points are given for each hour of video or a 12 page summary for a 30minute video Maximum extra credit allowed for the quarter is 20 points The list will be handed out the first lecture There is also a field trip around the Portland area which will take place 2PM 5PM on Tuesday Feb 19 2013 Cost of the field trip is 4 The trip will count 8 extra credit points 12 Class Notes Are available at Clean Copy 1720 SW Broadway for sale or available for free on D2L 13 Videotaped lectures I will miss no classes this quarter so no videotaped lecture 14 List of topics covered in class in order of presentation 3 Readings a Intro and Geologic Time and plate tectonics skim 174 b Earth s Materials 1 Minerals and the Rock Cycle skim 74105 2 Rock Materials RQD 214250 3 Igneous Rocks Volcanoes 106153 4 Sedimentary Rocks and Processes 154196 5 Metamorphic Rocks and Processes 197214 6 Stratigraphy Geologic amp Topo Maps 173182 7 Weathering and Erosion 319347 8 Soils mechanics highlights Wetland Clays 348394 9 Construction Materials handout c Geological Processes 1 Tectonic Processes a Structural Geology 251271 b Earthquakes 272318 2 Slope processes 500543 3 Stream processes 544595 4 Coastal processes 596638 5 Groundwater 396450 6 Geology of Portland Oregon handout PSU Library Reserve List for G301 extra credit videos Winter Term 2013 Instructions for extra credit videos Be sure to get the instructor s permission ahead of time if you wish to use a different source ie NOVA for your video review Each summary should include your name the title and length of the movie Each 60 minute video summary should equal one page a 30minute video 12 page etc 60 minutes 5pts 30 minutes 25 pts etc At the end of each summary please rate the film AF Be sure to relay facts from the movie you do not need to include every single detail but include information from throughout the whole movie This is not a critique exercise ALL PAPERS ARE TO BE TYPED on white or offwhite paper with one inch margins Times New Roman font and single or double spaced Papers that do not meet the length and content requirements may not receive full credit The deadline is 5pm Friday Mar 8th Please be courteous to the library staff there have been issues in the past A notice will be posted on D2L if videos are added or changed throughout the term These videos are there for you to enjoy and to supplement the material you are leaming and yes earn extra credit The following list is alphabetized for your convenience be sure to use the library call when requesting a movie A DVD will often have extra footage only the initial movie counts Title VHS or DVD Format Library Call Length in minutes America39s Tsunami Are we Next DVD Bur 201 2 90 At Risk Volcano Hazards from Mt Hood OR DVD Bur 201 31 l4 Cascadia The Hidden Fire DVD Bur 201 32 60 EME Corp Earthquakes VID Bur 201 24 20 EME Corp Glaciers VID Bur 201 22 18 EME Corp Plate Tectonics VID Bur 201 23 15 EME Corp Volcano VID Bur 344 31 18 Fire Mountains of the West VID Bur 344 10 32 Geysers Of Yellowstone VID Bur 344 12 45 Grand Canyon A Natural Wonder VID Bur 202 1 50 Loma Prieta Earthquake VID Bur 201 26 90 Jewel of the Earth NOVA special on Amber VID Bur 201 21 60 Inside Hawaiian Volcanoes VID Bur 201 10 30 In the Shadow of VesuVius VolcanoScapes II Mount Rainier Mt Rainier and Olympic Nature s Rage all hazards Oregon Field Guide Quake Potential in the NW Planet Earth Gifts from the Earth Rainier The Mountain Tales From Other Worlds Planet Earth The American EXperience San Francisco Quake The Corridors of Time Making of a Continent Pt1 The Eruption of Mount Saint Helens The Eruption of St Helen39s The Great Floods Missoula Floods The Story of America39s Great Volcanoes The Ultimate Guide Volcanoes The Walls came Tumbling Down VID Bur 201 15 VID Bur 201 18 VID Bur 202 8 VID Bur 344 30 VID Bur 201 25 VID Bur 201 8 DVD Bur 344 3 VID Bur 201 14 VID Bur 201 12 VID Bur 201 13 VID Bur 201 2 VID Bur 201 3 DVD Bur 201 1 VID Bur 201 7 DVD Bur 344 2 VID Bur 201 27 2nd Video on the same is optional When the Bay Area Quakes 20 Understanding Volcanic Hazards 1991 VolcanoScapes Pele39s March to the Pacific VolcanoScapes II Kilauea Volcano Rages On VolcanoScapes 3 Living on the Edge VID Bur 201 6 VID Bur 201 11 VID Bur 344 5 VID Bur 344 1 47 30 66 120 30 55 60 55 60 60 30 30 30 55 60 55 25 30 47 2 copies 60 INTRODUCTION TO GEOLOGY 1 wHAT IS GEOLOGY A STUDY OF EARTH MATERIALS B STUDY OF EARTH PROCESSES PASTPRESENT ABOVE AND BELOW GROUND C STUDY OF EARTH S HISTORY 2 USES OF GEOLOGY BY THE ENGINEER TRANSLATE AND PREDICT A CONSTRUCTION 1 AREAS OF CONSTRAINT THAT AFFECT DESIGN AND MAINTENANCE 2 RISKS WILL STRUCTURE SURVIVE 3 LOCATION OF A SITE 4 ECONOMICS INCREASE OR DECREASE COSTS 5 FORECAST FUTURE EVENTS GEOHAzARDS 3 RECURRENCE INTERVALS A VERY IMPORTANT CAN T BE wRONG B DEVELOPMENT OF NATURAL RESOURCES 1 MINING EXTRACTION 2 PETROLEUM EXTRACTION C wATER RESOURCES DEVELOPMENT amp PROTECTION 3 GEOLOGIC TIME J A ABSOLUTE TIME RADIOMETRIC DA39I39NG B RELATIVE TIME EVENT SEOUENCES C GEOLOGIC TIME SCALE 1 CENOZOIC o 65 MYA MAMMALS 2 MESOZOIC es 225 MYA DINOS 3 PALEOZOIC 225 570 MYA INVERTS 4 PRECAMBRIAN 570 MYA 5 BYA LITTLE OR NO LIFE 4 DYNAMIC EARTH A PARTS OF THE EARTH 1 CRUST UPPER 3 TO 70 KM 2 MANTLE 70 KM TO 3 OUTER CORE LIQUID 4 INNER CORE SOLID B PLATES SURFACE IS MOVING 1 LITHOSPHERE 0 100 KM THICK PLATES 2 ASTHENCSPHERE PLASTIC LAYER IN MANTLE THAT THE PLATES MOVE ON A 3 PANGAEA SUPERCCNTINENT THAT BROKE UP 200 MYA C PLATE BOUNDARIES wHERE QUAKES AND voLCANoS 1 SPREADING CENTERS RIDGES AND RIIT VALLEYS wHERE CRUST CREATED 2 CONVERGENT MARGINS TRENCHES wHERE CRUST DESTROYED SUBDUCTION A IF Two CCNTINENTS UPLIFT 3 TRANSIoRM MARGIN PLATES PASS BY ONE ANOTHER SAN ANDREAS FAULT 5 MINERALS A NATURALLY OCCURRING INORGANIC CRYSTALLINE COMPOUND CR ELEMENT B IDENTIFICATION CHEMICAL AND PHYSICAL CHARACTERISTICS G MAINLY PHYSICAL ONES LIKE HARDNESS CoLoR IRACTURE STREAK ETC C SILICATE MINERALS 95 OF MINERALS ROCK FORMING BASED ON ARRANGEMENT OF SILICA 3 TETRAHEDRA SI AND O D NON SILICATE MINERALS 5 6 ROCKS NATURAL AGGREGATES OF MINERALS A CLASSIFICATION BASED ON 1 COMPOSITION AMOUNTS 3 KINDS OF MINERALS 2 TEXTURE SIzE 3 SHAPE OF MINERAL GRAINS 3 FABRIC MINERAL GRAIN CONNECTIONS B MINERALOGY STUDY OF MINERALS C PETROLOGY STUDY OF ROCKS D OTHER DEFINITIONS 1 ROCK ENGINEER NATURALLY OCCURRING HARD PERMANENT MATERIAL REQUIRES BLASTING TO EXCAVATE DURABLE FOR EROSION CONTROL 2 STONE ROCK REMOVED FROM A SITE FOR BUILDING MATERIAL E TYPES OF ROCKS CLASSIFICATION BASED ON ORIGIN 1 IGNEOUS COOLING OF MAGMA 2 METAMORPHIC CHANGED FROM OTHER ROCK 3 SEDIMENTARYACCUMULATION 8 CEMENTATION OF SEDIMENTS L1 E TYPES OF ROCKS CLASSIF BASED ON ORIGIN 1 IGNEOUS ROCKS FORMED FROM COOLING AND SOLIDIFICATION OF MAGMA A VOLCANIC EXTRUSIVE COOL NEAR EARTH SURFACE FINEGRAINED B PLUTONIC INTRUSIVE COOL BENEATH THE SURFACE COARSE GRAINED C COMPOSITION SILICATE MINERALS amp INTERLOCKING GRAIN FABRIC 2 SEDIMENTARY ROCKS FORMED AT SURFACE UNDER NORMAL TEMPERATURE BY A ACCUMULATION AND CEMENTATION OF SEDIMENTS B OR BY CHEMICAL PRECIPITATION C COMPOSITION NON SILICATES AND OUART2 AND CLAvSamp GRANULAR FABRIC 3 METAMORPHIC ROCKS TRANSFORMED PRE EXISTING ROCKS BY HEAT PRESSURE OR CHEMICALLY ACTIVE FLUIDS A MANY ARE FOLIATED MINERALS IN LAYERS um 1 mus 5 Cquotn1 IvIl H475Tuh Iu ofquot 39 l39 39 39 B COMPOSITION MAINLY SILICATES amp INTERLOCKING FABRIC I F ROCK CYCLE ROCKS CHANGE THROUGH TIME SEE HANDOUT 7 ROCK MATERIALS A TYPES OF MATERIAL 1 ROCK DENSE AGGREGATE OF MINERALS 2 SOIL ROCK PARTICLES AND MINERAL SEDIMENTS EASILY EXTRACTED 3 FLUIDS wATER GAS MAGMA PETROLEUM B ENGINEERING CLASSIFICATION OF ROCKS 1 GEOLOGIC NAME OF ROCK BASED ON MINERALS 2 ROCK SUBSTANCE STRENGTH AND DEFORMATION PROPERTIES OF INTACT UNFRACTURED ROCK 3 ROCK MASS CONTINUITY CHARACTERISTICS BEDDING PLANES FRACTURES FAULTS JOINTS C ROCK SUBSTANCE CLASSIFICATION ASTM METHODS 1 SPECIFIC GRAVITY WEIGHT OF VOLUME OF ROCK 3 DIVIDED BY wEIGHT OF SAME VOLUME OF wATER RANGE IRoM 2 TO 6 HIGHER THE VALUE THE GREATER THE STRENGTH 2 POROSITY PERCENT HOLES 10 LOW 40 HIGH INDIFIECTLY MEASURE OF STRENGTH IoR HIGHER THE POROSITY THE LowER THE STRENGTH USED MAINLY BY GEOLOGISTS 3 VOID RATIO voLuME OF VOIDSVOLUME OF SOLIDS DECIMAL 4 DURABILITY HARDNESS ABRASION RESISTANCE TO SCRATCHING B TouGHNESS RESISTANCE TO SUDDEN IMPACTS C SOUNDNESS RESISTANCE TO FREEZETHAW AND wET AND DRY CYCLES 5 UNCONFINED CCMRRESSIVE STRENGTH LIMITING FORCEAREA A MATERIAL CAN WITHSTAND WITHOUT IAILuRE FAILURE CRACK 6 DEFORMATION BEHAVIOR 39I Qamp39I39 11 J 1 0 I I 39 0 39 39 39I 39 I q I PQ 39 39 if f 391 t 39 I 39 4 1 i39 39 39J39 1 n39 39 f39 39 2r l 3 p u 39 I 1 H I la 39 39 f r quot 39 39 39 39 3939l I 1 t r 39 39quot I 39 39 quot 39 39 Iquot39 quot39quot quotT 39II 39 quot 3939 39 39 394 39 39 Jz 4aJAL39 L 39f 3939t quotquot 393933939 quotquot39 4 39 39 o ti E J 1 s i 5 39 39 1 39 31RENGTH PSl KGCM2 gt 32000 gt 2250 16 32000 110 2210 5g2n2 5549 39z50139 E855 8 16000 4000 8000 lt 4000 lt 20 quot 39 rr 39 b I I b 39 o QESCRIPTIQN VERY HIGH HIGH STRENGTH MODERATE T oi 52001 39 I 39 quot39 39 39 39 39 39 H 39 r39 1 Z 39 39 r A 393939 39I quotquot39 v39 39 39n I c p quot43939 IQ u 39 FIELD TEST PING THUDNO MARK THUD FRACTURE THUD IMPRINT BURY HAMMER r39s3 quot39 f 3 39 quot39 0G I 39 2 39rquot 39 39 3939 39 31 39 39 39 39 quotquotu quot 39 39 39 39 quot39 i39 39 39o 1 c quotquotquot 5 73939 quotZzJ L 3quot quotquot 54 39 139 ET 0 39q t quot39f39 quotquotquotquotquot39V j rcw 39 1 quot3939 39ltgt 1 5 lt I 3939quot 39A39 3939 i 1 I 1391fv WYquotquotj 3939 39j39 393939 39r 0 39 39 lquotV n I r A 39 H 1 39 39 r 2 quotT 6 DEFORMATION BEHAVIOR STRESS STRAIN RELATIONS A STRESS EXTERNAL LOAD F FORCEAREA 1 COMPRESSIVE 2 TENSILE 3 SHEAR B STRAIN AMOUNT OF DEFORMATION FROM C ELASTIC RELATIONSHIP LIKE SPRING RETURNS TO ORIGINAL SHAPE 1 BRITTLE ROCKS 2 NO DENSIFICATION 3 NO PROGRESSIVE FAILURE Sq 55 V E hra39 v 2 MODULUS OF ELASTICITY SLOPE OF LINE P A STEEP VERY STIFF ROCKS 816 B LOW SLOPE YIELDING ROCKS I c39 K D PLASTIC BEHAVIOR DUCTILE ROCKS NONELASTIC 39 1 WHEN MANY PORES gives E 339 5170 N E PLASTIC ELASTIC BEHAVIOR 1 DENSIFICATION AT FIRST FROM PORES COLLAPSING 5mass E 51 A F ELASTICPLASTIC BEHAVIOR 1 MIXED COMPOSITION SO WEAKER MINERALS FAIL FIRST 2 ST VENENTS BEHAVIOR I Io P 391 Sf 39 39 12 G PLASTICELASTICPLASTIC BEHAVIOR 1 MOST COMMON 51quotAI39V 7 FAILURES A ELASTIC AT END BRTI39LE ROCKS DANGEROUS 1 ROCK BURSTS B PLASTIC AT END DUCTILE AT END D ROCK MASS CLASSIFICATION CONTINUITY OF MASS 1 MAINLY FROM CORES 2 WHY BAD A REDUCE ROCK STRENGTH B PATHWAYS FOR WATER C FAILURE SURFACES 3 EXAMPLES A JOINTS CRACKS COLUMNAR JOINTING B BEDDING PLANES SEDIMENTARY ROCKS C FOLIATION METAMORPHIC ROCKS D FAULTING CRACKS WITH DISPLACEMENT IZ E CAVl139ES LIMESTONE AND BASALTE 4 CORE RECOVERY o LENGTH OF CORE 39 lt 2397 11 LENGTH DRILLED 5 ROD ROCK QUALITY DESIGNATION ONLY COUNT PIECES gt 4 INCHES LONG CORE MUST BE gt 54 CM WIDE 2quot A VERY POOR 0 25 B POOR 25 30 C FAIR 30 75 D GOOD 75 90 E EXCELLENT 90 100 6 NORMALIZED ROD ROD 342 llv39FV ac39I39V4 I 00 A 742 Ir c39I39uI394 3 O 3970 754 2 uvL4 39 quotquotquotquotquot oO7o G 301 Geology for Engineers IGNEOUS ROCKS iv 1 Classi cation A Mineral Composition 1 Ma c Dark Minerals like Olivine amp Pyroxene 2 Felsic Light Minerals like Quartz amp Feldspar Silicic 3 Intermediate Some Felsic and Some Ma c B Textures 1 Crystalline a Aphanitic Can t see with naked eye Rapid Cooling Volcanic b Phaneritic Can see with naked eye Slow Cooling Plutonic c Pegmatitic Very large grains slow cooling lots of water in the magma 2 Glassy NonCrystalline A Glass a Obsidian Black Glass Magma into water so very rapid cooling b Pumice White many holes so oats 3 Porphyritic 2 Grain Sizes Slow Cooling Followed by Rapid Cooling common in Composite Volcanoes 4 Pyroclastic Fragments of Volcanic Debris a Ash Less than 17 Diameter b Cinder 17 to 1 forms Tuff c Lapilli 1 to 3 d Volcanic Bomb gt 3 H IGNEOUS ROCK CLASSIFICATION COMPOSITION FELSIC INTERMEDIATE MAFIC TEXTURE 1 GLASS OBSIDIAN PuwIce X 39 APHANITIC RHYOLITE ANDESITE BASALT PHANERITIC GRANITE DIORITE l GABRO jquot 39 C Comparison to Types of Igneous Rocks 1 Extrusive Vesicular FineGrained 2 Intrusive No Holes CoarseGrained i D Classi cation Based on Texture and Composition I See Chart in Text Igneous Rock Classi cation Compositiongt F elsic Intermediate Ma c Texture Glass Obsidian X X Pumice Aphanitic Rhyolite Andesite Basalt Phaneritic Granite Diorite Gabbro l gt 100 names for Igneous Rocks 2 Granite Most Common Intrusive Great Building Stone Mountain Building On Continents 3 Andesite Named in Andes Common in the High Cascades 4 Basalt Most Common Volcanic Rock Scoria Basalt with Vesicles Flow Top Weathers to Brown and Red E Columnar Jointing Vertical Cracks in Basalt from Cooling Polygonal Cracks 1 Grout to Keep Water Out Big Problem for Engineers 2 Teton Dam Disaster Idaho July 1976 a 1 Billion Damage 14 Dead b Earthen Dam Fails when Water Goes Through Cracks in Columns Supposedly Grouted FLOW TOP WEATHERS TO BROWN amp RED E COLUMNAR JOINTING VERTICAL CRACKS IN BASALT FROM COOLING POLYGONAL CRACKS 1 GROUT TO KEEP WATER OUT BIG PROBLEM FOR ENGINEERS 2 TETON DAM DISASTER IDAHO JULY 1976 A 1 BILLION DAMAGE 14 DEAD B EARTHEN DAM FAILS WHEN WATER GOES THROUGH CRACKS IN COLUMNS SUPPOSEDLY GROUTED 2 ENGINEERING CHARACTERISTICS OF IGNEOUS ROCKS A INTRUSIVES 1 STRENGTH HIGH TO VERY HIGH 16000 32000 PSI 2 DEFORMATION AND FAILURE ELASTICPLASTIC B EXTRUSIVE MASSIVE FLOWS DIKES SILLS 1 STRENGTH HIGH 16000 32000 PSI 2 DEFORMATION AND FAILURE ELASTIC c EXTRUSIVE POROUS VESICLES TUFF BRECCIA PUMICE SCORIA quot 1 ROCK STRENGTH vERY LOW To LOW o aooo PSI 2 DEFORMATION AND FAILURE PLASTIC ELASTIC 4 VOLCANIC PROCESSES A CENTERS OF VOLCANIC ACTIVITY 1 VOLCANO MOUNTAIN OF ITS OWN EFIUPTIVE MATERIALS VENT FOR MAGMA 2 CONE PIPE CRATER 3 ACTIVITY A ACTIVE ERUPTED IN LAST 1oooo YEARS B DORMANT GEOTHERMAL ENERGY BUT No ERUPTION IN LAST 10000 YEARS C EXTINCT NO GEOTHERMAL 8 NO POSSIBILITY B MATERIALS OF VOLCANISM 1 LAVA MAGMA THAT HAS LOST ITS GASES 2 GASES MAINLY wATER OO2 N S02 HCL S CL A MOST OF ATMOSPHERE EXCEPT OXYGEN IROM VOLCANOES 3 PYROCLASTICS ASH CINDER LAPILLI BOMBS C DISTRIBUTION MOST ON PLATE BOUNDARIES 1 15 DIVERGENT MARGINS 2 30 CONVERGENT MARGINS quotRING OF FRE3939 3 5 WITHIN PLATES HOT SPOTS D SUMMARY QUIET ERUPTIONS EXPLOSIVE 1 MATERIALS GASES GASES LAVA LAVA PYROCLASTICS 2 ROCKS BASALT ANDESITE RHYOLITE OBSIDIAN PUMICE TUFF BRECCIA 3 FEATURES SHIELD VOLCANO COMPOSITE VOLCANO PROCESSES PLATEAU BASALT CINDER CONE I 9 CALDERAS NUEES ARDENTES DIATREM ESDOIVI ES E QUIET ERUPTIONS 1 SHELD VOLCANO A BASALT B LOW ANGLES UP TO 5 DEGREES C LAVA FLOWS OVER LAVA FLOWS D MANY OCEANIC E EXAMPLES MAUNA LOA MAUNA KEA SOLAR SYSTEM VOLCANOES 2 PLATEAU BASALTS FISSURE ERUPTIONS A MAGMA OUT OF A FISSURE AND FLOODS AREA B EXAMPLE COLUMBIA RIVER PLATEAU LUNAR MARIA DECCAN INDIA 3 LAVA FORMS A PAHOEHOE SMOOTH ROPY SATIN FLOWS FROM HIGH TEMPERATURE MAGMA B AA ROUGH BROKEN SURFACE MORE VISCOUS MAGMA LOWER TEMPERATURE C PILLOW LAVA FORMED UNDER WATER 4 LAVA TUBE CAVES COMMON IN BASALT A APE cAvES ST HELENS BBEND F EXPLOSIVE ERUPTIONS MORE VISCOUS MAGMA 1 COMPOSITE VOLCANO ALTERNATING LAVA 8 PYROCLASTICS A MAINLY ANDESITE B S39l39EEP SIDED 30 DEGREES c SUBDUCTION ZONES ISLAND ARCS amp ON LAND D EX OASOADES ANDES ALEUTIANS JAPAN 2 OINDER CONES MAINLY PYROCLASTICS A SMALLER STEEPSIDED TO 40 DEGREES B ANY COMPOSITION C EX PARACUTIN CAPULIN PORTLAND HILLS 3 DOMES MAINLY RHYOLITIC LAVA A SMALLER VOLCANOS B AFTER LARGE VIOLENT ERUPTIONS C Ex ST HELENS DOME MONO ORATERS MT PELEE 4 NUEE ARDENTE FIERY CLOUD ERUPTION A MAINLY GASES AND HOT PYROCLASTICS B MT PELEE MARTINIOUE 1902 25000 KILLED Z I C MAINLY IN CARIBBEAN 5 CALDERA COLLAPSED COMPOSITE VOLCANO AIETER VIOLENT ERUPTION A ORATER LAKE B YELLOWSTONE 20 MYA 12 MYA 6 MYA C KRAKATOA 1883 D TAMBOR0 INDONESIA 1315 E vESuvIuS MT SOMMA POMPEII 79 AD F SANTORINI GREECE LOST CONTINENT OF ATLANTIS 1500 BC G OTHER FEATURES 1 FUMAROLES STEAM VENTS LOTS OF DISSOLVED ELEMENTS 2 HOT SPRINGS GROUNDWATER HEATED BY HOT ROCKS OR DEEP FAULTS BELOW 3 GEYSERS HOT SPRINGS THAT PERIODICALLY ERUPT INTO THE AIR OLD FAITHFUL H HAZARDS TO LIVES PROPERTY AND RESOURCES 1 LAVA ILOwS 2 TEPHRA PYROCLASTICS 3 LAHARS DERRIS FLOWS IN STREAM VALLEYS START Z2 FROM MELTING OF SNOW AND ICE WITH PYROCLASTICS ON MOUNTAIN 4 FLOODING 5 SILTING OF RIVERS 6 EARTHQUAKES 7 EROSION MAYBE NOT SO GREAT 8 TSUNAMI SEISMIC SEA WAVE OLD TIDAL WAVE 9 CLIMATIC CHANGE COOLING 10 QUESTIONS TO ASK A WHAT IS THE POTENTIAL FOR ERUPTION B WHAT TYPE OF ERUPTION WILL HAPPEN Sl39I39NG OF CRITICAL INSTALLATIONS WATER SUPPLIES RIVERS COMMERCE J ST HELENS MAY 18 1980 1 BULGE 5 FTDAY 2 EARTHQUAKE 51 AT 832AM 3 LANDSLIDE DOWN TOUTLE RIVER LARGEST HISTORICAL SLIDE 4 LA3939ERAL BLAST 5 UPWARD BLAST Z3 G301 PLUTONIC PROCESSES A PLUTON INTRUSIvE RoCIlt STRUCTURE MAINLY GRANITE 1 voUNGER THAN SURROUNDING ROCK B SHALLow PLUTONS 1 voLCANIC PLUGS FEEDER PIPES ERoDED NECK OF VOLCANO A DEVILS TOWER SHIP ROCK BEACON ROCK 2 SILL TABULAR PLUTON SHEET BETWEEN SEDIMENTARY BEDS CoNCoRDANT PARALLEL A PALISADES SILL CEMETARY RIDGE GREAT WHIN SILL 3 DIKE DISCORDANT PLUTON INJECTED IN FISSURES IN oLDER ROCKS CUTS ACRCSS FEATURES 4 LACCOLITH THICK DOMED SILL A LASAL MoUNTAINS amp HENRY MOUNTAINS C DEEP PLUTONS 1 STOCK LARGE MASSIVE PLUTON lt so KM2 AT SURFACE 2 BATHOLITH gt so KM2 MOSTLY GRANITE SIERRA NEvADAS D ORE VEINS DIKES FILLED WITH MINERALS AROUND BATH 2 H G301 SEDIMENTARY ROCKS 3 chap L A ORIGIN SEE SED ROCK CYCLE CHART I 1quot B LITHIFICATION MAKING SOFT SEDIMENTS INTO ROCK 1 COMPAC3939lON PRESSURE DECREASES PORE SPACE 2 CEMENTATION DEPOS39l39lON OF MINERALS IN PORES A CALCITE SOIT ACID RAIN DESTROYS B SILICA OUARTZ HARDEST CEMENT C IRON OXIDE REDBROWN COLOR D CLAY SOFT C CLASTIC SEDIMENTARY ROCKS CONSOLIDATED SEDIMENTS 75 OF SEDIMENTARY ROCKS 1 PARTICLE SIZES ROCKS T T A BOULDER gt10quot B COBBLE 25 10quot an C PEBBLESGRAVEL 08 25quot CONGLOMERATE UI D SAND 002 08quot SANDSTONE 1 GEOLOGISTS gt 10 SIEVE 2 ENGINEERS gt 4 SIEVE E SILT 00015 002quot SHALE 1 GEOLOGISTS lt 230 SIEVE SedgnQvar393 L Z 2 ENGINEERS lt 200 SIEVE F CLAY E b 2 CHARACTERISTICS A SETTLED IROM wATER B GRANULAR TEXTURE C 75 OF SEDIMENTARV ROCKS D HISTORY OF PAST ENVIRONMENTS 3 CONGLOMERATE CEMENTED ROUNDED GRAVEL IN SAND MATRIX A ENVIRONMENT IAST STREAM ALLUVIAL FAN 4 BRECCIA CEMENTED ANGULAR GRAVEL A ENVIRONMENT LTl39LE TRANSPORT DISTANCE LANDSLIDES VOLCANOS FAULT zONES 5 SANDSTONE CEMENTED SAND A ENVIRONMENT RIVER DUNE BEACH B USES BUILDING STONE e SHALE HARDENED MUD SILT AND CLAY A ENVIRONMENT OUIET wATER LAKE OCEAN 1 IF IIzzES WITH HCL OCEAN B SHALE FISSILITY SPLITTINC INTO PLANES 27 C MUDSTONE BREAKS INTO MASSIVE CHUNKS D USES BRICKS TILES CEMENT POTTERY E COLORS RED HEMATITE BLACK ORGANICS D ORGANIC SEDIMENTARY ROCKS FROM LIVING ORGANISMS 1 COAL CARBONIFIED REMAINS OF PLANTS A ENVIRONMENT OLD BOG OR MARSH 2 CHERT FINE GRAINED SILICA FROM BODIES OF DIATOMS RADIOLARIANS AND SPONGES 4 LIMESTONE ROCK OF CALCITE A ENVIRONMENT TROPICAL OCEANS B FOSSILIFEROUS CONTAINS SHELLS C MICRITE NO FOSSILS RECRYSTALLIzED D CHALK BODIES OF ONE CELLED FORAMINIFERA WHITE CLIFFS OF DOVER E DISSOLVES EASILY FORMS CAVES 1 KARST TOPOGRAPHY REGIONS OF LIMESTONE WITH ABUNDANT CAVES SINKHOLES DISAPPEARING STREAMS GROUNDWATER EASILY POLLUTED F PROBLEM FOR DAMS LOSE WATER IN CAVES IN THE LIMESTONE 23 E PRECIPITATED SEDIMENTARY ROCKS EVAPORITES 1 ROCK GYPSUM 2 ROCK HALITE 3 OTHERS BORAX AND POTASH 4 ROCK SALT GOOD STORAGE AREAS FOR PETROLEUM NOT GOOD FOR RADIOACTIVE SUBSTANCES SALT DOMES WHICH ARE MOVING UPWARD F STRATIFICATION FORMATION OF DEPOSITIONAL LAYERS 1TYPES A PARALLEL WATER DEPOSITION UNDER QUIET ENERGY B CROSSSTRATIFICATION STRATA UNEVEN FROM VARIABLE ENERGY AND DIRECTIONS STREAMS AND WIND BEST EXPRESSED IN SAND SEDIMENTS 2 SORTING ARRANGEMENT OF SEDIMENTS IN A STRATUM A UNIFORM SORTING PARTICLES ALL SAME SIZE 1 LITTLE VELOCITY CHANGE IN TRANSPORTING AGENT 2 HIGH ENERGY GRAVEL PARTICLES Z I 3 LOW ENERGY SILT AND CLAY PARTICLES B GRADED BEDDING WITHIN A STRATUM COARSEST GRAINS ON BOTTOM AND SMALLEST ON THE TOP 1 FORMED WHEN ABUNDANT SEDIMENT DUMPED INTO OUIET wATER 2 MISSOULA ILOOD RHYTHMITES 3 IN OCEANS TURBIDITES C NONSORTED BEDS RANDOM DISTRIBUTION 1 GLACIAL SEDIMENTS LANDSLIDES G FEATURES OF SEDIMENTARY ROCKS 1 ROUNDNESS OF GRAINS EXPLAINS AMOUNT OF TRANSPORT A LONG DISTANCE WELL ROUNDED B SHORT DISTANCE ANGULAR 2 RIPPLE MARKS SHOw WHICH WAY IS UP amp DIRECTIONS OF wIND 3 MUD CRACKS SHOw EXPOSURE TO AIR LAGOON PLAYA FLOODPLAINS 4 RAINDROPS EVIDENCE OF EXPOSURE TO AIR 5 FOSSILS FOUND MAINLY IN SEDIMENTARY ROCKS TELLS ENVIRONMENT OCEAN ETC 6 COLOR TELLS OF ENVIRONMENT A RED HEMATITE wELL DRAINED B GRAY POORLY DRAINED C BLACK ORGANICS 7 CONCRETIONS MINERAL PRECIPITATION AROUND A NUCLEUS FILLING A CAVITY HARDER THAN SURROUNDING ROCK H IMPORTANCE OF SEDIMENTARY ROCKS 1 HISTORY OF EARTH 2 CONTAIN FOSSIL FUELS 3 BUILDING USES LIMESTONE CEMENT SANDSTONE SHALE BRICKS 4 BEAUTY 5 ROCK SALT I ENGINEERING PROPERTIES OF SEDIMENTARY ROCKS 1 CLASTIC SEDIMENTARY ROCKS VARIABLE DEPENDING UPON SORTING MINERALS CEMENTATION VOIDS A STRENGTH VERY LOW SHALE TO VERY HIGH OuARTz CEMENTED SANDSTONE BFACTORS 1 HIGH STRENGTH GRAINS UP 2 INCREASED SORTING POORLY GRADED DOwN 3 INCREASED ROUNDING DOwN 4 INCREASED CEMENTATION UP 5 INCREASED vOIDS DOwN C DEFORMATION USUALLY PLASTICELASTIC WITH VOIDS COLLAPSING AT FIRST 5 D SHALE RED FLAG WEAK ROCK 1 LOwER SLOPE ANGLES SLOPE STABILITY PROBLEMS WEAK FOR FOUNDATIONS 2 LIMESTONE A STRENGTH MEDIUM TO HIGH 16 32 kpsi B DEFORMATION PE IF MICRITE PEP IF FOSSILIFEROUS 6 4 O L 1 5 1 939quot 405539ls C STRENGTH DECREASES WITH INCREASED CLASTIC PARTICLES AND FOSSILS IN IT DECREASES WITH INCREASE IN VOIDS 3 EVAPORITES GYPSUM ROCK SALT amp COAL A STRENGTH VERY LOW TO LOW lt 8 kpsi B DEFORMATION ELASTICPLASTIC 39I CFACTORS 1 DISSOLUTION CREATES WEAK ZONES J LOW LEVEL NUCLEAR WASTES 1 WANT Low PERMEABILITY ROCKS 2 FAILURES IN TENN amp KENTUCKY A LEAKS IN LIMESTONE CAVITIES AND BATHTUB EFFECT OF SHALES A 3 NOW Low RAINFALL LOW PERMEABILITY ROCKS CLAY AND PLASTIC LINERS LEACHATE DRAINS METAMORPHIC ROCKS A DEFINITION ROCKS CHANGED BY HEAT PRESSURE ANDOR CHEMICALLY ACTIVE FLUIDS B NONFOLIATED ROCKS NO BANDING OF MINERALS BECAUSE GRAINS OF ROCK EOUIDIMENSIONAL 1 OUARTZITE METAMORFHOSED SANDSTONE SIO2 A CEMENT STRONGER THAN GRAINS B SUGARY SURFACE 2 MARBLE METAMORFHOSED LIMESTONE CALCITE A LARGER CRYSTALS THAN LIMESTONE B WHITE IMFURITIES MAKE IT OTHER COLORS C SOFT H3 SO HIGHLY POLISHED 3 COAL METAMORFHOSED ORGANICS A PEAT 15 CARBON so wATER DULL BROWN B LIGNITE COAL 35 CARBON 45 wATER C BITUMINOUS COAL 50 CARBON 5 wATER D ANTHRACITE COAL 95 CARBON 3 wATER SHINY BLACK COLOR E GRAPHITE 100 CARBON C IOLIATED ROCKS BANDING OF MINERALS 1 SHALE CLAY MINERALS SED ROCK 2 SLATE CLAY BECOMES ORIENTED SMALL MICAS 3 PHYLL3939E MICAS BECOME SHEETS 4 SCHIST LARGE MICA FLAKES 5 GNEISS MICAS BECOME FELDSPARS 6 ROCK CLEAVAGE SPLITS ALONG FOLIATION PLANES SLATE PHYLLITE SCHIST A GNEISS RANDOM SPLITTING 7 GRANITE BECOMES GNEISS 3 BASALT TO BLUESCHIST TO GNEISS D PROCESSES OF METAMORPHISM 1 CONTACT METAMORPHISM HEAT FROM IN39rRuSION IS AGENT NEw MINERALS A HORNFELS SHALE TO A quotBRICKquot 2 HYDROTHERMAL METAMORPHISM AGENT IS CHEMICALLY ACTIVE FLUID MAINLY wATER A OLIvINE TO SERPENTINE OCEAN RIDGES 8 AROUND PLUTONS 3 CATACLASTIC METAMORPHISM AGENT IS PRESSURE A ALONG FAULTS ROCKS SHEARED 8 GROUND UP B FORMS BRECCIA GOUGE AND MYLONITE WHICH IS COMBINATION OF THEM C DYNAMIC METAMORPHISM ANOTHER NAME 4 REGIONAL METAMORPHISM HEAT AND PRESSURE ARE AGENTS A MAINLY IN MOUNTAIN RANGE CORES B MOST COMMON FORM OF METAMORPHISM C PRODUCES FOLIATION E WHERE TAKES PLACE 1 RIDGES HYDROTHERMAL ALTERATION 2 CONVERGENT ZONES WHERE MOUNTAIN BUILDING IS A LOW TEMPERATURE PRESSURES IN TRENCH BLUESCHISTS AND GREENSCHISTS B HIGH TEMPERATUREPRESSURE INLAND UNDER MOUNTAINS FOLIATIONS CONTACT METAMORPHISM CATACLASTIC F ENGINEERING PROPERTIES OF METAMORPHIO ROCKS 1 OuARTzITE AND HORNIELS A ROCK STRENGTH INCREASED FROM METAMORPH 1 HIGH TO VERY HIGH 1632 KPSI B DEFORMATION amp FAILURE ELASTIC 2 SLATE AND PHYLLITE A ROCK STRENGTH MEDIUM TO HIGH 332 KPSI B DEFORMATION amp FAILURE ELASTIC 3 MARBLE A STRENGTH MEDIUM 3 16 KPSI B DEFORMATION amp FAILURE ELASTICPLASTIC 4 SCHIST DEPENDS ON FOLIATION 8 LOADING A PERPENDICULAR T0 FOLIATION 1 HIGH STRENGTH 1632 KPSI 2 ELASTIC DEFOFIMATION B PARALLEL TO FOLIATION 1 STRENGTH LOW 43 KPSI 2 DEFOFIMATION ELASTIC C IN BETWEEN FOLIATION 1 STRENGTH INTERMEDIATE 2 DEFOFIMATION IN BETWEEN 5 GNEISS NO PLANES OF WEAKNESS A STRENGTH MEDIUM TO HIGH 8 32 KPSI B DEFORMATION ELASTICPLASTIC G PROBLEMS WITH METAMORPHIC ROCKS ZONES OF WEAKNESS WATER INFLOW OVERBREAK IN TUNNELS 1 ST FRANCIS DAM FAILURE 1928 LOS ANGELES A FAILED FEW MONTHS AFTER BUILT 400 DEAD WALL OF WATER 30 50 M HIGH B WATER INTO FOLIATION CRACKS amp YELLOW ZONE FAILED amp DAM FAILED ALSO PART OF ANCIENT LANDSLIDE c cnoss SECTION 2 HAROLD TUNNEL DENVER wATER BOARD TUNNEL 37 KMLONG cONcRETE LINED THROUGH IGNEOUSMETAMORPHICS A INFLOWS OF GROUNDWATER ALONG cRAcKs MORE GROUT MORE COSTS 1 GNEISS gt SCHIST gt GRANITE B MORE OVERBREAKS IN METAMORPHIC ROCKS MORE COSTS 1 GNEISS amp SCHIST gt GRANITE 2 DIAGRAM OF TUNNEL PAYLINE OVERBREAK G301 STRATIGRAPHY GEOLOGIC TIME MAPS A STRATIGRAPHY STUDY OF ROCK STRATA amp THEIR CHRONOLOGY 1 FORMATION BASICROCKUNIT FOR MAPPING BASED ON PHYSICAL CHARACTERISTICS A NAME TYPE LOCALITY AND ROCK TYPE IF ONE TYPE PIERRE SHALE COLUMBIA RIVER BASALT IF NO DOMINANT ROCK USE FM LIKE TROUTDALE FORMATION B SUBDIVISIONS MEMBERS C GROUP ASSEMBLAGE OF FMS 2 LAW OF ORIGINAL HORIZONTALITY BEDS DEPOSITED HORIZONTALLY 3 SUPERPOSITION OLDEST BEDS AT BOTTOM AND YOUNGEST AT TOP 4 LAW OF FAUNAL ASSEMBLAGES LIKE ASSEMBLAGES OF FOSSILS GIVES LIKE AGES FOR THE ROCKS 5 LAW OF CROSS CUTTING RELATIONSHIPS IF A FAULT FOLD OR UNCONFORMITY CUTS ACROSS A ROCK UNIT IT IS YOUNGER THAN THE UNIT 6 UNIFORMITARIANISM NATURAL LAWS OPERATING TODAY ALSO PREVAILED IN THE PAST PRESENT IS KEY TO PAST 7 CORRELATION PIECING TOGETHER THE COLUMN OVER AN AREA B UNCONFORMITIES BURIED EROSION SURFACE BETWEEN TWO DEFOSITIONS FAILURE PLANES amp CONDUITS FOR WATER 1 ANGULAR UNCONFORMITY BEDS AT ANGLE WITH ONE ANOTHER FIRST BEDS DEPOSITED THEN TILTED THEN ERODED AND FINAL DEPOSITION 2 DISCONFORMITY BEDSPARALLEL ABOVE AND BELOW 3 NONCONFORMITY SEDIMENTARY BEDS ON CRYSTALLINE ROCKS C GEOLOGIC TIME SCALE 1 CENOZOIC MODERN LIFE LAST 65 MY 2 MESOZOIC MIDDLE LIFE 230 65 MYA A DINOSAURS DOMINATED 3 PALEOZOIC ANCIENT LIFE 600 230 MYA 4 PRECAMBRIAN 4600 600 MYA TIME BEFORE COMPLEX LIFE FORMS D GEOLOGIC MAPS DISTRIBUTION OF GEOLOGIC FORMATIONS ON THE SURFACE 1 CONTACTS SEPARATESFORMATIONS 2 SYMBOLS FOR FORMATIONS Sw AGE AND FORMATION NAME 3 GIVES STRUCTURE FAULTS FOLDS BED INCLINATIONS 4 ON A TOPOGRAPHIC MAP BASE 5 CROSS SECTIONS GIVE 3D VIEW 6 SURFICIAL MAP GIVES THE SURFICIAL DEPOSIT GLACIAL STREAM WIND 7 AGRICULTURAL SOIL MAP DISTRIBUTION OF SOILS HORIZONS E TOPOGRAPHIC MAPS GIVES RELIEF AND GEOGRAPHY 1 CONTOUR LINES GIVE ELEVATIONS 2 LOCATION A LATITUDELONGITUDE BCLTOWNSHIP AND RANGE C UTM UNIVERSAL TRANSVERSE MERCATOR DIGITAL 3 QUADRANGLES USGS 75 MIN 15 MIN 1100000 AND BIGGER 4 COLORS A RELIEF IN BROWN CONTOURS B WATER BLUE C CULTURAL FEATURES BLACK D HIGHWAYS RED E UPDATES PURPLE G301 WEATHERING AND EROSION CHAPTER 9 A WEATHERING ALTERATION OF ROCKS FROM EXPOSURE TO AIR WATER AND ORGANICS TO MORE STABLE FORMS 1 END PRODUCTS SOILS SEDIMENTS SALTS 2 EROSION REMOVAL OF WEATHERING PRODUCTS FROM THE SITE OF WEATHERING 3 ROCK TO SAPROLITE TO GRUS TO SEDIMENT 4 JOINTS PATHWAYS FOR wEATHERINC B MECHANICAL WEATHERING FRAGMENTATION OF ROCKS INTO SMALLER PIECES wITHOuT MINERAL CHANGE 1 CHARACTERISTICS A BOULDERS TO COBBLES TO GRAVEL TO SAND TO SILT CLAY MAINLY ClIEMICAL wEATHERINC B DOMINATES IN COLD CLIMATES C ESTABLISH STRESS UNTIL BREAKS 2 FROST WEDGING wATER INTO CRACKS AND FREEzES AND EXPANDS 9 REALLY HYDROFRACTURING A MOST EFFECTIVE wHEN MANY CYCLESYEAR B FORMS TALUS AT BOTTOM OF CLIFFS L1 3 SALT CRYSTAL GROWTH SPEEDS UP wEATHERING ESPECIALLY ON COASTS A EVAPORATION OF SALT wATER IN ROCK CRYSTALS EXPAND AND SPALL ROCK B HYDRATION OF SALT IN ROCK 1 CLEOPATRA S NEEDLE 4 ExFOLIATION SPLT139lNG INTO SCALELIKE LAYERS BY SURFACE UNLOADING LIKE ONION SKINS A ESPECIALLY IN HOMOGENEOUS ROCKS LIKE GRANITE B MANY TIMES COMBINED WITH CHEMICAL WXING C LARGE SCALE ROCK DOMES LIKE HALF DOME D MINERS RAPID ROCK BURSTS 5 FIRE SPALLING HIGH TEMPERATURES CAUSE EXPANSION OF OUTSIDE LAYERS OF ROCKS FORM FLAKES 6 PLANT ROOTS 7 SWELLING CLAYS SMECTITES A ABSORB wATER WHEN DRY AND RELEASE IT WHEN DRY H 3 ABRASION GRINDING OF ROCK WHILE IN TRANSPORTATION C CHEMICAL WEATHERING CHANGES IN CHEMICAL COMPOSITION OF MINERALS 1 MAINLY IN SOILS wHERE wATER AND MINERALS ARE IN CONTACT 2 MINERALS DECOMPOSE TO A CLAYS A B IRON OXIDES C SALTS OCEAN SALTS D QUARTZ SAND 3 AGENTS OF CHEMICAL WEATHERING A OXYGEN COMBINES WITH METALS TO FORM OXIDES quotRUSTquot B CARBONIC ACID C02 H20 H2CO3 1 WEAK ACID IN SOILS 2 JOSEPH BLACK DISCOVERED CO2 C STRONG ACIDS MINES AND IuMAROLES D wATER 1 HYDRATES ADSORBED ONTO MINERALS 2 HYDROLYSIS CHEMICALLY REACTS WITH SILICATES E AIR POLLUTION 4 COMPLETE BREAKDOWN OF ROCKS A GRANITE 1 OuARTz TO SAND GRAINS 2 FELDSPARS TO CLAY 3 SALTS 3 BIOTITEAMPHIBOLE TO IRON OXIDES amp CLAY B BASALT 1 OLIVINEPYROXENE TO IRON OXIDES amp CLAYS 2 FELDSPARS TO CLAYS amp SALTS C CLAYS REFLECT THE CLIMATE 5 WEATHERING TYPES A HOMOGENEOUS WEATHERING ROUNDED ROCK FORMS LIKE IN GRANITE B DIFFERENTIAL WEATHERING UNEVEN SURFACES C SPHEROIDAL WEATHERING BOULDERS FROM WEATHERING ALONG PREEXISTING JOINTS 1 COMMON IN BASALTS AROUND HERE D wEATHERING RINDS WEATHERED MINERALS AT SURFACE OF ROCK FRAGMENT GETS THICKER wITH 139lME 6 RATES OF CHEMICAL wEATHERING A CLIMATE 1 TEMPERATURE wARMER THE IASTER wxING 2 wATER MORE wATER IASTER wxING A MUSHROOM ROCKS B CLEOPATRAS NEEDLE B SURFACE AREA MORE JOINTS IASTER wxING C SLOPE ANGLE HIGH ANGLE LESS wxING D AIR POLLUTION E CRYSTAL SIZE LARGER CRYSTALS wEATHER IASTER THAN SMALL ONES 1 GRANITE gt RHYOLITE 2 GABBRO gt BASALT E ORIGINAL ROCK 1 MAFIC gt INTERMEDIATE gt IELSIC A BASALT gt RHYOLITE I 35 L E dd B GABBRO gt GRANITE 2 QUARTZ SLOwEST wEATHERING D wEATHERING AND ENGINEERING 1EFFECTS A wEAKENS ROCK STRENGTH DOwN B LOSS OF ELASTIOITY C DENSITY DOwN AS POROSITY UP D MOISTURE CONTENT UP 2 BEWARE A DON T BUILD STRUCTURES ON wEATHERED ROCK ESP ARCH DAMS NEED MAX STRENGTH 3 ELASTIOITYI B wEATHERING OF BUILDING STONE amp ROAD AGGREGATE C LEADS TO SLOPE IAILURE 3 MAP OUT wEATHERED ZONES ESP ALONG JOINTS FAULTS AND OTHER DISCONTINUITIES AF FRESH B Sw SLIGHTLY wEATHERED c Hw HIGHLY wEATHERED D cw COMPLETELYwEATHEREDSAPROLITE 5 E EROSION REMOVAL amp TRANSPORTATION OF SURFICIAL MATERIALS BY AN AGENT 1 EVENTUALLY GET A DEPOSIT OF SEDIMENT A NEED TO RECOGNIZE SOURCE amp USES B NEED TO MAINTAIN SUPPLY OF STREAM SEDS C NOT TOO MUCH SEDIMENT OVERLOAD STREAM 2 AGENTS GRAVITY MASS WASTING WATER ICE WIND WAVES 3 wATER MOST IMPORTANT AGENT A RAINSPLASH B OVERLAND FLOw c RILL EROSION D GULLY EROSION E STREAM EROSION 4 UNIVERSAL SOIL LOSS EQUATION PREDICTS AMT OF EROSION FOR DIFFERENT LAND SETTINGS MAINLY FOR CENTRAL US FARMLAND USE TO PREVENT EROSION A EOUATION A RKLSCP 1 A ANNUAL SOIL LOSS TONSACREYR SEDIMENT YIELD 52 2 R RAINFALL FACTOR INTENSITY amp DURATION 0 350 100 HERE 3 K SOIL ERODIBILITY FACTOR POROSITY PERMEABILITY MOISTURE PARTICLE SIZE A 0 TO 7 TONSACRE 7 EASILY ERODED LIKE SILT AND FINE SAND GRAVEL AND CLAY ARE LOW 4 LS SLOPE LENGTH AND STEEPNESS 5 C CROPPING FACTOR HIGH FOR ROW CROPS 8 BARREN LAND LOW FOR GRASS 6 P CONSERVATION TECHNIQUES DISRUPTS OVERLAND FLOW TERRACING B DONE FOR AGRICULTURE BUT FOUND THAT CONSTRUCTION HAS BIGGEST YIELDS DON T GET SEDIMENT INTO STREAMS 100X 5 IF CONSTRUCTION NEED A CONSTRUCT DURING LOWEST RAINFALL FALL B CLEAR ONLY SMALL AREAS AS YOU NEED C TEMPORARY VEGETATION ON SOIL STOCKPILES D DIVERSIONS COLLECT OVERLAND FLOW E DETENTION BASINS TO HOLD SEDMENT NEED IN TUALATIN BASIN F STRAw AND HAY BALES REDUCE RAINSPLASH G MONITOR RESULTS OF TREATMENT 6 EROSION BY WIND CLEARLY DEMONSTRATED IN 1930 S A wIND VELOCITY DURATION LENGTH OF OPEN AREA USE SHELTERBELTS TO REDUCE B SOILLAND SURFACE 1 MOST SUSCEPTIBLE SOlL FINE SAND NExT IS SILT 2 MOISTURE COHESIVE SO WHEN DRY wIND EROSION BECAUSE LOST COHESION 3 VEGETATION WIND EROSION wORST AFTER PLOWING C CRUST FORMATION AFTER FINES REMOVED COARSE GRAINS FORM CRUST ON SURFACE AND PROTECT AS ARMOR 5 G301 SOILS LECTURE ENGINEER 3 GEOLOGY vIEw 1 INTRODUCTION A GEOLOGST S OR AGRONOMST S SOIL wEATHERED UPPERMOST LAYERS OF ORGANIC HUMUS AND INORGANIC SEDIMENTS CAPABLE OF SUPPORTING LIFE B ENGINEERING SOIL MINERAL MATTER THAT LACKS STRENGTH MAY INCLUDE SAPROLITE DIG WITH A SHOvEL DISAGGREGATES WITH GENTLE MECHANICS C ROLE OF SOIL IN ENGINEERING 1 BUILDING MATERIAL DAMS LEvEES SLOPES 2 STRUCTURES FOUNDED IN IT 3 SLOPES ADJACENT TO A STRUCTURE D DIFFERENT DEFINITIONS RELATED TO SOILS 1 SURFICIAL DEPOSIT A GEOL CEMENTED SEDIMENTS FROM STREAMS GLACIERS LANDSLIDES DUNES B ENGINEER TOPSOIL 2 UNCoNSoLIDATED A GEOL UNCEMENTED SEDIMENTS B ENGIN SoIL wHERE wATER SQUEEZED OUT FROM STATIC LoAD 2 DESCRIBING SoIL FoR ENGINEERING PURPOSES A CoLoR TELLS STATE OF DRAINAGE 1 REDORANGE wELLDRAINED 2 GRAY PooRLY DRAINED Fe REDUCED 3 REDGRAY MOTl39LES REDOXYMORPHIC FEATURES FLUCTUATING wATER TABLE AND POORLY DRAINED 4 USE MUNSELL CoLoR BOOK B pH SoIL REACTION ACIDBASE 1 CAN Do IN IIELD WITH TAPES 2 BEST IN LAB Do 11 wATER 3 ACIDIC CoRRoDES STEEL a AFIECTS CEMENT C BULK DENSITY MAINLY USED BY GEOLOGISTS 1 DRY WEIGHTUNIT VOLUME 2 gcc USE TUBE OF KNOWN VOLUME 0 J pf L D UNIT WEIGHT SIMILAR TO BULK DENSITY BUT CE S 1 WEIGHT OF MATERIALVOLUME OF MATERIAL 2 MOIST UNIT WEIGHT VOIDS FILLED WITH WATER AND AIR 3 DRY UNIT WEIGHT VOIDS FILLED WITH AIR 4 SATURATED UNIT WEIGHT VOIDS FILLED WITH WATER E POROSITY VvVt X 100 n 1 RANGES o 100 SAND 4o50 SEE p80 F VOID RATIO e VvVs n1n 1 624 Gsunit weight dry 1 2 RANGES 0 TO INFINITY DENSE ABOUT 3 LOOSE AT 1 G MOISTURE CONTENT W WwWs X 100 WtWsWs X100 1 RANGE o 100 H GRADATION PASSING 1 WELLGRADEDPOORLY SORTED Q0 paM6 Qfgvd 3044 53 my 2 POORLY GRADEDWELL SORTED 397 5 3 GAP on SKIP GRADED 0 paw Q tquot 4 GEOLOGISTS GRADING CURVE CUMULATIVE o uh 30 grand 5 S CI I BOUNDARIES GEOL ENGIN SOILS BOULDERS 256mm 305mm COBBLES 64mm 76mm 76mm PEBBLES 2mm 10 475 4 2mm SAND 062230 074200 050250 SILT 002 005 002 CLAY J COHESIVE SOILS FINEGRAINED AND DON T DISAGGREGATE K A1TERBERG LIMITS A PLASTIC LIMIT WHEN DRY SOIL IS WET ENOUGH TO AGGREGATE MAKE WORMS PL B LIQUID LIMIT WHEN SOILS FLOWS MACHINE LL C PLASTICITY INDEX PI LL PL 0 1 L COMPRESSIBILITY DEGREE OF REDUCTION IN VOLUME A SOIL MASS MAY UNDERGO UNDER A NATURAL OR ARTIFICIAL LOAD DECREASE IN Vv MAINLY BUILDING ON THE SOIL 1 CONSOLIDATION COMPRESSIBILITY FROM A STATIC LOAD MAINLY BY DRIVING WATER FROM VOIDS A SETTLEMENT NATURAL CONSOLIDATION B TO REDUCE SETTLEMENT 1 REMOVE SOIL IF THIN 2 PLACE SURCHARGE ADDITION ON LOTS OF TIME BEFORE 3 ADD VERTICAL DRAINS FOR SPEED 2 COMPACTION REDUCTION OF VOID SPACES BY MECHANICAL MEANS REPEATED LOADING 3 VIBRATION ARTIFICIAL DENSIIICATION OF SOIL wHEN SOIL USED AS CONSTRUCTION MATERIAL BUILDING wITH THE SOIL A Owc OPTIMUM wATER CONTENT PROCTOR TEST P 103 TOP OF CURVE WATER WHEN MAX DRY DENSITY M SHEAR STRENGTH RESISTANCE OF SoIL To SLIDING OF ONE MASS AGAINST ANOTHER 1 HOW TO MEASURE A DIRECTLY DIRECT SHEAR TEST B INDIREcTLv uNIAxIAL TRIAxIAL 2 MOHRCOULOMB EQUATION AT FAILURE F39 IO 39I39a A SHEAR STRESS AT FAILUFIE 7 B COHESION C c ANGLE OF INTERNAL FRICTION quot1 3 SHEAR STRENGTH IN NONCOHESIVE SOILS A c 0 N0 COHESION B MU A PORE PRESSURE 4 cASE HISTORY TRANSGANA MANITOBA 1913 A GRAIN ELEvAToR RoTATED 27 DEGREES B ON PLEISTOCENE LAKE CLAYS c CLAYS AT DEPTH ABSORBED WATER AND LOST SHEAR STRENGTH AND ELEVATOR FAILED 4 cLASSIIIcATION OF ENGINEERING SOILS ABACKGROUND 1 PARTICLE SIzE AND PLASTICITY 2 PREDICT cOMPAcTION SE1TLEMENT DRAINAGE IROST SUSCEPTIBILITY ExcAvATION PROBLEMS EMBANKMENT cHARAcTERISTIcs 3 As GRAIN SIzE DOwN PROBLEMS UP A CLAY MAIN PROBLEM DO EASIEST BY PI B UNIFIED SOIL cLASSIIIcATION SYSTEM 1 cORPS OI ENGINEERSBUREAU REcLAM 1953 BASED ON CASAGRANDE 1940 P 956 2 USE 4 AND 200 SIEvES amp ATTERBERG LIMITS A IF gt 50 ON 4 GRAvELS B IF gt 50 PASSES 200 SILTCLAY SOIL c IF NEITHER OI ABOVE SANDY SOIL 3 USE LETl39ERS BASED ON LAB DATA A Gw GP GM Gc GRAvELS B Sw SP SM Sc SANDS c ML MH SILTS D cL CH CLAYS E OL OH ORGANIcS UNIFIED SOIL CLASSIFICATION SYSTEM Group Field Identification Procedures Major Divisions Symbolsa Typical Names lexcluding particles larger than 75 mm l3b 393l0fY Cl353lllC Ili039 and basing fractions on estimated weights Clllefia 1 2 3 4 5 6 3 W weitgmded gme grave Sand mu Wide range in grain sizes and substantial w D I gt 395 G 39 amounts of all intermediate particle sizes quotI quot 5039 gig E 3 E Lures itte or no tnes 3 d 3 C dQ grmrrrr hm 1 3 39 50quot to 2 O C E 2 E 393 39 i D 2 S a at 5 3 39 39 39LI 3939i39 39 25 E D S I R F 3 3 n 5 ures I rno ines M 131 E E to 0 2 5 5 2 E as E O is 39 a in 9 Nonplastic fines or fines with low plasticity E 05 E o Not nitrting all gradation rt iiirtinctits for W 39 O E 5 3 E 393 quot39 quot GM Sitty gravrls gravelsandsilt mixtures o E 390 39 I9 q 539 D I for identification procedures see Ml below In 393 U E 39 39 5 quot 3 I393 I E L 3 9 5 3 U 3 39U gquot3 3 Atlerlmrtz limits lielnw Aline or Above Aline WI 2 39139 a5 eltii E 5 I I12 32 31 i less than I Prawcrn U E 39 5 4 quot39 E gt quotquot gr quot39 Clayey gruvcls grovelsandclay Plastic fines for identification procedures 3 5 397 to 3 1 d 7 E 9 E 5 393 E 3 O G0 mixtures see CL below g E E Q 0 Li 2 Lirrlit Jl3 liinils l1Ul t A lino cnizs rog fr l E E SE 3 5C 3 willi l I grrnitr Ihnii 7 dunl Wlnlmls i 39 iiI quot H quot39 2 E 2 G E E L A SW wgll radod 3md5 gravcllj S nd3 Wide range in grain sizes and suliittantial 53 2 E 5 3 3 D60 3 E 5 a 3 E g 3 g o 3 little or no fines amounts of all intermediate particle sizes E to5 5 greater than 6 0 3 3 a 4 at3i to at Um 2 39quot 8 3 3 3 3 3 E cs 2 E at 3 H 0 Q g H 3 g 2 qp poorly graded sands gravelly sands Predominantly one size or a range of sizes 3 Q E E g g 030 I 53 393 3 5 6 lime or no nes with some intermediate sizes missing 9 D D at as ct j bt lV et n l and 3 gr 395 s 3 39 2 East59 DIII m J E 9 39 quot 23 I 3 II quot939 3 r 393 E E E E 39 1 3 SM 3 d d l Nonplastic fines or fines with low plasticity E E i 5 3 1 Not m quotlquotquotl39I all l5 39lquotll0quot lquotquotlUllquot939 0nl5 ffquot 9W i 39 2 o I I o s I y san s san SI t mixtures I ca O In I 2 E 3 I 3 ps E E E 35 g 3 or ldentlllcallon procedures See Ml be owl 5 E 0 3 3 59 Atterlierg limits below Alint or Limits plotting in 3 EL 3 J 0 6 4 I0 ilvl less than i zone with III ln 2 H V as quotquot Pl stic fines for ide t39f39 tion rocedures I 393 4 and 7 h TE 51 3 3 0 SC Clay ey sands sandclay mixtures gee CL bclowy n I ma p E 39ittt39rberg limits alioie A liiie cases c ff 5 D D with H grntrr than 7 dual syntbols Identification Procedures 3 4 g on Fraction Smaller than No 10 Sieve Size E c 3 Dry strength Dilatancy Toughness E 3 crushing reaction lconsistency Plasticity Chart 53 E 1 characteristics to shaking near Pll 0 For Laboratory Classiticmton of rineGained Sons I F O 339 E 3 392 Inorganic silts and very fine sands rock I 5 5 E u iii Ml flour silty or clayey fine stands or None to slight Quick to slow None V 5 3 5 E 5 clayey silts with slight plasticity 3 1 60 s a 2 g 2 2 I I I I I I I m I 2 E 3 3 Inorganic clays of low to medium 39 None to Wquot I at Comparing Soils at equal quid quotmi39 5 In 6 Cl plasticity gravelly clays sandy Medium to high I Medium 4 h 39 quot Irgt z clays silty clays lean clays S 0quot i 3 50 t Ug quot 55 alld dw quotquotquot9lh 3939 339 35 393 E w U VfIl1 increasing plasticity index i z I 52 5 E3 5quot Organic silts and organic silty clays of Slight to I39 E5 E Q3 01 low plasticity medium Slow Slight E E do E N c 5 395 Inorganic silts nticaceous or 3 quotii E Mll diatomaceous fine sandy or srlilgcllljluri Slow to none 81133 tn D E 30 1 3 Q 9 silty soils elastic silts e m 1 g E 53 G E 2 CL ca 0 E U 3 CH lI39IllE39gy39 sl39IlC clays of high plasticity fat Hlg39lLilZIhvery None High MH o quot39 quot 3939i 539 E I0 Ct ML ML M d L h 39 l39l39 1g 0 or E 53 Organic clays of medium to high None to we SI hi i 7 quot 0 plasticity organic silts e mm 0 lg slow medium 4 quot 0L 0 l l l l l l J Readily identified lw color odor spiinftv fool 0 lo 20 30 do 50 60 0 80 90 loo Hllihly organlc soils Pl Peat and other highly organic soils and frequently ll fibrous texture Liquid Limit lllff U3 quot E tlquot19T WELBTWBY9 l3 fD9quotlm0nl Sflilolon U950 quotThe Unified Soil Classification Systemquot Tocirti39col Mernaranrimn No 3 39l5 Appendix 393939ll50 grain dinntetir fin mm corresponding to 80 prissing liy Wl39ll39Il as taken from grtin Lhiiracteristics of Soil Groups Pertaining to Flmbanlcments and Foundations 1953 and Appendix B Characteristics of Soil Groups Pertaining to llnitds distribution curvr ind Airfields 1957 and A K Howard 1977 quotLaboratory Classification of Soils Unified Soil Classi cation Systemquot Earth Sciences Trai m39ng Manual lo 4 US Bureau of Reclamation Denver 56 pp lloiindary classifications soils possessing characteristics of two groups are designated by combinations of group symbols For example GWGC well fTiIlCl gravel sand mixture with clay binder 39Ill sieve sizes on this chart are US Standard ii39quot L cu gtIskgig lquot I I c AASHTO HIGHWAY PEOPLE 1920 us BUREAU ROADS AM ASS STATE HIGHWAY TRANS OFFIC 1 10 AND 200 sIeves 2 A1 A3 GRAVELS AND SANDS GOOD SUBGRADES I 3 A4A5 SILTY FAIR SUBGRADE 4 A6A7 cLAYeY POOR SUBGRADE 0 USDA SOIL scIeNceGeoLoGY TEXTURES 1 use 10 AND 230 sIeves 2 CLASSIFICATION uses SOIL TAXONOMY HIERARCHICAL SYSTEM SIMILAR T0 BIOLOGY 5 GeoLoGIc SOIL WEATHERED ORGANIC SEDIMENTS A ONLY JOB WHERE YOU CAN START AT THE TOP DIGGING A HOLE B PROFILE successIoN OF DISTINCTIVE LAYERS IN THE SOIL 1 o HORIZON UNDECOMPOSED ORGANICS TWIGS NEEDLESLEAVES 2 A HORIZON TOPSOIL BLACK HUMUS DECOMPOSED ORGANICS AND MINERAL MATRIX zoNe OF BIOLOGICAL ACTIVITY 3 E HoRIzoN LEACHED ZONE WHITE coLoR IRoN ALUMNUM0RGANlCS REMOVED BY ACID WATERS INTENSE WEATHERING MAINLY IN IoREsTs 4 B HoRIzoN zoNE OF ACCUMULA139ION OF WEATHERING PRoDUcTsIRoN ALUMINUM CLAY REDDEsT PART OF SOIL A Bt CLAY AccUMULATIoN VERY STICKY FILMS B Bk CALICHE cALcITE WHITE DRY CLIMATE c Bg MOTTLED BED AND GRAY PATCHES PooRLY DRAINED D Bx DENsE SILT FRAGIPAN HOLDS UP wATER E Bs VERY RED ABUNDANT IRoN F Bw oNLY INcREAsE IN SLIGHT RED coLoR 5 c HoRIzoN oxIDIzED PARENT MATERIAL 6 PARENT MATERIAL ARocK B SURFICIAL DEPosIT STREAM DEPOSIT DUNE GLACIAL MATERIAL LAN DSLIDE C SOIL DEVELOPMENT SOIL GROWS AND CHANGES CHARACTERISTICS WITH TIME 1 DRY GRASSLAND A A pa9 399 EAquotu E quot9 E as 1 c 55 2 MOIST GRASSLAND A c 3 Tquot 82 39gt 39539 G 3 MOIST FOREST 0 A 9 quotquot A 2 6 5 398 quot39 3939 32 95 4 wETLAND quot39 c p 9 9 quot 392 D FACTORS OF SOIL DEVELOPMENT 1 CLIMATEVEGETATION MOST IMPORTANT CLIMATE CONTROLS VEGETATION ANIMALS ANTS WORMS AND GOPHERS 2 TIME sTREssED ABOVE 3 TOPOGRAPHY SLOPE ORIENTATION AND ANGLE A sOuTH SLOPES wARMER AND DRIER B UPLANDS WELL DRAINED AND DEEP MIDSLOPES HAVE THIN sOILs LOwER SLOPES MANYTIMES ARE POORLY DRAINED 3 HAVE BURIED SOILS 4 PARENT MATERIAL A GRANITE SANDY AND THICK SOIL B BASALT THIN CLAYEY SOIL EUSES 1 ESTIMATING AGES OI DEPOSITS CHRONOSEOUENCE A LATERITIC SOILS END POINTS OF wEATHERING OLD SOILS LOTS OF IRON AND ALUMINUM OXIDES LOTS IN TROPICS GREAT GRAPE GROWING SOIL IN OREGON 2 FREQUENCY OF GEOLOGICAL HAZARDS A BURIED SOILS DATED PALEOSOLS B wHAT AND wHEN 3 PAST CLIMATES AND VEGETATIONS 4 PRODUCTIVITY OI CROPS 5 LAND USE PLANNING 6 SOIL EROSION wHICH SOILS wORST 7 wHERE ARE SHRINK SwELL SOILS G SOIL EROSION MAJOR ENVIRONMENTAL PROBLEM 1 RATES HIGH NONRENEWABLE RESOURCE A FORMATION 80 400 YEARS1quot TOPSOIL B EROSION gt NEw SOIL FORMA3939l0N BY 2 BILLION TONSYR IN US C EROSION OF 5 TONS OF SOIL FOR EACH TON OF GRAIN PRODUCED D FILLING IN RESERvOIRS RIVERS DELTAS 2 CAUSES AND CURESquot MAN HAS ACCELERATED A FARMERS ONTO MORE STEEP LANDS 3 SEMI ARID REGIONS 39rERRACE SLOPES B FARMERS MORE Row CROPS ALTERNATE GRASS STRIPS WITH Row CROPS ROTATION C MORE FARMLAND FROM FORESTS CONVERT LESS H SOIL SURVEYS 1 GENERAL ECOLOGYGEOLOGYCLIMATE OF AREA 2 SOILS PROFILE DESCRIPTIONS OF TYPE LOCALITIES 3 LAND USE BASED ON SOIL SERIES A ALSO SOIL CLASSIFICATION OF EACH B ENGINEERING CHARACTERISTICS OF EACH SOIL 4 GENERAL SOIL MAP OF THE COUNTRY 5 MAPS OF wHOLE COUNTY AIR PHOTOS 5 SOLU39I39IONS A DON T BUILD oN IT B Low ACTIVITY soIL BLANKET ON TOP USUALLY NEED AT LEAST 2 3 METERS c REINFORCED PIERs BELow CLAYS so IoUNDATIoN Is FLOATING D LIME sTABILIzATIoN CA0H2 E PoRTLAND cEMENT sTABILIzATIoN F FLY AsII sTABILIzATIoN G IsoLATE WATER DRAINs PIPEs MEMBRANES IIGUTTERs oN HOUSES I IIEAT sTABILIzATIoN J TREEs No cLosER THAN 12 EXPECTED HEIGHT IT IS A PUMP K BUILD oN WELLDRAINED SITES L DON T ovERwATER REPAIR LEAKY PIPEs 6 SOIL CLASSIFICATION CH OR VERTISOL 7 PROBLEM SOILS A GLACIAL SOILS VARIABLE PARTICLE SIZE KAMES AND KETTLES IN THE TILL BIG BouLDERs B LOESS WINDBLOWN SILT 1 OPEN sTRuCTuRE sATuRATE BEFORE BUILDING T0 DENSIFY IT BEFORE LoAD 2 WEAKLY CEMENTED HIGHLY ERODIBLE CUT CLIIIs VER3939ICAL AND GuTTERs AT BOTTOM C oRGANIC soILs BOGS MARSHES SWAMPS PEAT 1 LOW sTRENGTH HIGHLY COMPRESSIBLE 2 LoTs OF wATER IN THEM DRAIN 3 GooD souRCEs OF TOPSOIL D EXPANSIVE SOILS CoNTAIN SMECTITE 1 IoRIvIED IN DRY AREAS CR WITH VOLCANICS 2 EXPANDS wHEN wET AND CoNTRACTs WHEN DRY so 2ooo VOLUME INCREASE 3 6 BILLIONYR IN us IouNDATIoNs RoADs 4 DETECTION BMS MODEL A PI gt 15 LL gt 36 CLAY gt 32 B HIGH RISK PI gt 29 LL gt 54 C E COLLAPSING SOILS DECREASE IN VOLUME WHEN SATURATED 1 DRY SOILS AT EDGES OI MOUNTAINS ESP ON ALLUVIAL IANS 2 COHESION IROM GYPSUM AND CLAY IN VOIDS 3 COLLAPSE IRRIGATION DISSOLVES CLAY AND GYPSUM AND VOIDS COLLAPSE 4 HYDROCOMPACTION 5 UTAH LAS VEGAS F QUICK CLAY SOILS SENSITIVE CLAYS 1 LOW DENSITY SANDSSILTS MARINE 2 SALTS wEATHERED AwAY amp VIBRATION CAUSES DEPOSIT TO DENSIIY SO INCREASE PORE wATER PRESSURE AND DECREASE IN SHEAR STRENGTH T0 ZERO amp DEPOSIT FLOWS G WETLANDS wET SoILS IF quotJURISDICTIONALquot THEN CAN39T BUILD UPoN UNLESS YOU MAKE NEw ONE PONDS wATER oN IT AT LEAST 2 WEEKSYR IN GROWING SEASoN MARCH OCTOBER No NET Loss 1 HYDRIC SoILS MOTTLES WITHIN ToP 2oquot 2 HYDROLOGY PONDS wATER AT LEAST 2 WEEKS EACH YEAR IN GROWING SEASoN MARCH TO OCTOBER 3 HYDRIC PLANTS CATTAILS SEDGES wILLowS 7 AND SUBSIDENCE SINKHOLES AND DEPRESSICNS A REMOVAL OF FLUIDS ESPECIALLY IN LIMESTONE AREAS CAvES RooIS CANNoT SUPPCRT WEIGHT OF STRUCTURES ABOVE AND IALL IN B DRAINAGE OF ORGANIC SoILS WILL SINK C COLLAPSE OF CAVITIES ABANDONED MINES Fed TQxLu39quote S OQ F UL 6 q maA 0 I S 3 M ge DQJre m Maf Mgtn NM sxrgurtj 3ltllt13 HUKWS S CL1 quot K3 PukgkC S1lquotCL0j P451 836 5 s O H g1 If or anrci 95 1 Qgraqnfc clru13 39 ciaqezq 53 x L CL I 0 39 Cl05U1 SIN 1 5 C amp V7 1 M L s lr1 clwD C quot1 SW5 sIv n 5444 3 39 SC is 333 Z Z I s39 5 A QL gilijt W S c1 fme S5 Pmuwv eafmj bg Sa f Guf g H75 G301470570 CONSTRUCTION MATERIALS 1 INTRODUCTION 30 OF MATERIAL MINED EACH YEAR ARE FOR CONSTRUCTION A IOUR CATEGORIES OF MATERIALS EXTRAC3939ED FOR USE BY HUMANS 1 METALS AND METALLIC ORES 2 MINERAL IUELS 3 GROUND wATER 4 INDUSTRIAL ROCKS AND MINERALS 2 ECONOMICS OF NATURAL MATERIAL FOR BUILDING A UNIT VALUE VALUE PER TON B PLACE VALUE VALUE BASED ON DISTANCE FROM THE SOURCE TO MARKET 1 AUSTRALIA GRAVEL HAS HIGH PLACE AND UNIT VALUE SINCE VERY LITTLE THERE 2 CONSTRUCTION MATERIALS RARELY IMPORTED OR ExPORTED BECAUSE Low UNIT VALUE 3 DIMENSION STONE BUILDING STONE MECHANICALLY CUT A USES 1 EXTERIORINTERIOR FINISH P E19 2 FLOORING 3 MONUMENTS 4 SIDEWALKS B SOuRcES MAINLY OUARRIES c HISTORY OF DIMENSION STONE IN US 1 PRE1945 COMMON IN ALL BUILDINGS A WASHINGTON MONUMENT MARBLE FROM 3 QUARRIES 1845 1885 2 POST 1945 COSTS TOO HIGH SO USED LESS A ONLY FOR ENTRANCES 8 LOBBIES B ARTIFICIAL COMBINATION OF RAW MATERIALS D PRODUCTION IN US 1986 STONE TONNAGE 1 GRANITE 74 2 LIMESTONE 62 3 MARBLE 3 4 SANDSTONE 34 5 SLATE 16 6 OTHERS 6 VALUE MIL 42 36 26 22 18 I T E DESIRED CHARACTERISTICS 1 EASE OF QUARRYING 2 DURABILITY AND SLow WEATHERING 3 CoLoR BEAUTY 4 FREE OF IRON 5 TAKES PoLISH F EXAMPLES 1 MQST USED GRANITE BECAUSE wEATHERS SLOWING AND STRONG AND BEAUTIFUL 2 MARBLE TODAY USED MAINLY INSIDE BECAUSE OF ACID RAIN WEATHERING oN BUILDING ExTERIoRS 3 SAN DSTQNE BEST QNES wITH QUARTZ CEMENT 4 SLATE ExPENSIvE To QUARRY BECAUSE HAS To BE SAwED AND SPLIT OUT OF QUARRY No BLASTING 5 BASALT GABBRO DIABASE TRAP RQCK BAD BECAUSE IRON MINERALS GIVE A RUSTY STAIN 4 AGGREGATES MIXTURES OF MINERAL AND ROCK PARTICLES A SIZES 1 FINE AGGREGATES PASSES 4 SIEvE 2 COARSE AGGREGATES 475MM 101 MM 4quot 3 OPTIMUM SIzE 127 CM OR 1 2 quot B CRUSHED AGGREGATE 1 DESIRABLE CHARACTERISTICS A STRENGTH B ABRASIVE RESISTANCE C LOw POROSITY D NO REACTIvE COMPONENTS E BRITl39LE 2 AGGREGATE PRODUCTION IN THE US CRUSHED ROCK TYPE TONNAGE VALUE MIL 1 LIMESTONE 146 134 2 TRAP ROCK 2o 22 3 GRANITE 13 13 4 MARBLE 4 4 5 SANDSTONE 6 3 6 OTHERS 43 14 3 TRAP ROCK ABUNDANT HERE AND MAKES GREAT AGGREGATE IoR RoAD METAL AND CONCRE39I39E 4 LIMESToNE MoST USED BECAUSE A NoT HARD so EASY To CRUSH B LESS ABRASIVE To cRuSHING EQUIPMENT c ABUNDANT AND GooD STRENGTH D NEEDS IoR GooD LIMESToNE AGGREGATE 1 uNIIoRM So No FOSSILS 2 NONPOROUS 3 FREE or cHERT oRGANIcS AND PYRITE c NATURAL SouRcES OF AGGREGATE MAIN SouRcE OF AGGREGATES 1 ALLuvIuM GLAcIAL TILL DUNES 2 DO NOT TAKE FROM ACTIVE FLOOD PLAIN OR BEACH D ARTIIIcIAL SouRcES 1 CLAY To BRICKS 2 SLAG 3 INCINERATED URBAN TRASH 39 I 4 GLASS 5 FLY ASH 6 SHELLS E USES NoNc0NcRETE 1 RAILROAD BALLAST WELLGRADED 3 No FINES 2 PARKING LOTS 3 Rock FILL DAMS 4 BITUMINOUS MIX ASPHALT 5 EMBANKMENTS 6 ROAD METAL NEED CLEAN WELLGRADED A PARTS OF A ROAD SYSTEM 7 FILL BEWARE OF SE139rLEMENT WEATHERING AND FROST ACTION 3 RIPRAP A ARMoR NEEDED FoR ERoSIoN FROM wAvES B STREAMS DAMS SHORE WHERE USED C NEEDS 1 STRENGTH SOUNDNESS 2 LOW POROSITY 3 ANGULAR COMPACTION 4 gt 17cm DIAMETER 9 ROCKFILL AGGREGATE ON SOILS ON DOWNSTREAM SIDE OF EARTHEN DAMS A PREVENTS RAINSPLASH B NEED ANGULAR EQUIDIMENSIONAL ROCK C PARTICLE SIZE gt OH TO GRAVEL F USES CONCRETE 1 REQUIREMENTS A TEXTURE NO FINES B WELLGRADED IN SANDSGRAVELS C UNIFORM QUALITY D NO REACTION E NO FLAT SHAPE F NO SMOOTH SURFACES G NO POROUS SEDIMENT H HIGH STRENGTH T I I NO SULIIDE MINERALS J NO COATINGS ON AGGREGATES WASH TO REMOVE THESE BEFORE USING J NO SILICA RICH AGGREGATES CHEMICALLY REACT wITH CONCRETE CA NA K AND OH IROM SE39l39139ING OI CEMENT COMBINES wITH SILICA TO FORM A GEL wHICH REACTS WITH wATER TO MAKE wEAK 1 SOLUTIONS USE LOw ALKALAI CEMENTS ADD POZZOLANIC CEMENT NO SILICA RICH ROCKS IN AGGREGATE RHYOLITE ANDESITE PHYLLITE TUFF SHALE DACITE CHERT OPAL CHALCEDONY F LIGHT wEIGHT AGGREGATE PRODUCES A DENSITY lt 135 GCC 1 USES Low wEIGHT NEEDED BY SOME STRENGTH GOOD FOR INSULATION 2 LOw STRENGTH 2oo 5000 PSI 3 EXAMPLES PUMICE CINDER VERMICULITE CORAL FLY ASH PERLITE H F r a my4 39 39ItIquotl39l39 r 1 39 quot quotquot39 39 w 39 t it r 1 39 p F a mya quot 39J39 39 t D r r I v39quot391lr rs 1139 i 39 quot 39 39 r quot L 399 1quot quotquot339 39iquot39quot39 13939 a39 f r 39 1 39t39 r 392 H39zquotquot39quot ftiiI1Cl 12 quot A 39 39 39pgt r 39 quot1 quotquotV g l3939 39I i I9 Oxidation Chemically oxidation is the loss of elec trons that accompanies many chemical reactions This results in an increase in positive valency ln weathering the term is usually restricted to the reaction of this type involving oxygen to form oxides or oxygen plus water to form hydroxides Iron oxides and hydroxides typically impart red and yellow staining of rocks and soils Although these colors are desirable for some ornamental purposes their appearance after construction can be a nusance The oxidation of iron contained in a mineral crystal lat tice will disrupt the lattice either by collapse or by increasing its susceptibility to other weathering pro cesses Oxidation also occurs after ferrous iron Fe has been released from a mafic silicate by hydrolysis If this ferrous iron enters an oxidizing environment it will form a precipitate containing ferric iron Fe3 Hydration The addition of water to a mineral struc ture forms a hydrate In some salts this can have the physically disruptive effect discussed earlier Hydration reactions are particularly important with clay minerals which may incorporate water in their crystal lattices Hydrolysis Water is a dipolar molecule which makes it an active solvent Water usually containing other dis solved ions will displace metal cations from silicate lat tices and lead to the production of new mineral struc tures and compositions Although it represents a gross simplification the following reaction illustrates the results of hydrolysis 2lltAlSiO3 3H2O HAlslo clslo 2llt 2OH Orthoclase Clay Mineral The water often contains acids that aid the process especially carbonic acid The common products of hydrolysis weathering are dissolved silica OH ions aqueous metal cations and clay minerals There is still an incomplete understanding of how hydrolysis combines with other weathering reactions to attack silicate minerals Loughnan 1969 summarizes much of what is known about the leaching of metal cat ions such as Ca Na K and Mg from silicate lattices The process involves surface hydration acid attack entry of water molecules into lattice spaces vacated by cations and eventually the formation of new mineral structures especially clays Winkler 1975 suggests that silicate weathering proceeds rapidly enough to produce discoloring and softening of stone surfaces and even pit ting and crumbling during prolonged exposure to an urban environment The effect is most pronounced in some varieties of basalt 0 lquot398zixiii ROCK AND STONE as CONSTRUCTION MATERIALS 135 ROCK AND STONE AS CONSTRUCTION MATERIALS Bates 1960 notes that fggr general categories of mate rials are extracted from the earth for human use 17net asZr l d metallic ores 2 mineral fuels 3 ground water and 4 other substances particularly industrial rocks and minerals Many of the materials in the latter category are used in construction practice These materials will be dis cussed here because as construction materials they interact closely both with humanity and with geological processes Although the construction industry accounts for over onehalf of the production value of nonmetallic economic rocks and minerals a variety of other non metallics are essential raw materials for other industries They are used in the chemical industry agriculture the ceramics industry as abrasives and as additives for met allurgy Bates 1960 gives an excellent discussion of the occurrence uses economics extraction and processing of these essential earth materials Industrial rock stone and minerals differ in their eco nomics from both metallic ores and mineral fuels Whereas the latter have uniue properties that give them a relatively high that is value per tonne the former generally are valued by their proximity to construction sites This ce va results from the high transportation costs for such bulk materials as building stone sand and gravel or various aggregates for con crete Many of the materials that we will discuss here will be those of high place value Generally in contrast to most materials of high unit value the industrial rocks and minerals are produced in large bulk from widely distrib uted geologic occurrences Processing is usually simple and the materials are rarely imported or exported Building Stone A walk through the older sections of cities in the north eastern United States shows the importance that stone enjoyed in construction prior to the midtwentieth cen tury The famous brownstone homes in New York City were faced with Triassic sandstone quarried from the Connecticut River Valley The importance of building stone in the nineteenth century is exemplified by the transportation of red sandstone from Arizona to Den ver Colorado for construction of the Brown Palace Hotel during the late 18005 Generally however the construction industry uses what is available locally such as granite in Vermont Minnesota Wisconsin and Aber deen Scotland and limestone in Bedford Indiana and Kingston Ontario The Washington Monument in Wash ington DC presents a contrasting example of utilization of building stone and transportation costs The first 152 ft 165 m of the monument were built between 1845 L4r 1iQ 5 6LfiCiIlKS C14quot L r I 5434 Ktfl lUL 7 5 136 ROCK lTS STRENGTH DURABILITY AND USES and 1854 with marble from the Piedmont Province quar ries at Texas Maryland just north of Baltimore When funds were depleted construction halted in 1879 work recommelnced on the monument and marble from Lee Massachusetts was used for the next 4 m This marble proved too costly so the remainder of the monument was completed by 1885 using marble from nearby Cockeysville Maryland The distinct color difference between the Texas marble white coarsegrained nearly pure calcium carbonate and the Cockeysville marble pale gray finegrained magnesium rich can be seen in the monument today Since 1945 stone facing has become an expensive decorative aspect of construction Modern buildings emphasize artificial combinations of raw materials glass concrete steel and bakedclay products Nevertheless there is a continuing demand for quality building stone to lend elegance and variety in modern architecture The most important characteristics of building stone are tex ture color durability weatherability and its ability to take polish Building stone is separated from natural rock masses hich consists of blocks that are mechanically cut to a specified size and shape In urban areas far from rock quarries glacial erratics can serve as a source of dimension stone The Mormon Temple in Salt Lake City Utah wasconstructed with granite cut from erratics in the glaciated Little Cottonwood Canyon of the Wasach Mountains to the east of the city United States con sumption of dimension stone was 2 million tonnes in 1976 The most common lithology of dimension stone in r39 3f i 39 c Figure 520 Granite rock quarry at Barre Vermont Photo courtesy of T M Crft rhs in uarries Figure 520 One basic product is stone tw jj the United States is granite 37 percent followed by limestone and dolomite 31 percent and sandstone including quartzite 17 percent Table 55 Quarry operations present several hazards as a con sequence of extraction of the resource There are sev eral sources of extreme stress on rock in quarries the most common being the weight of overlying rock and residual tectonic stresses The compressive strength of a freshly quarried rock can be as much as 50 percent less than the same rock aged39 5 to 6 months following removal from the ground Kieslinger 1967 The expres sion of stress removal or unloading can be rock bumps in the bottom of quarries or the more dangerous explo sive strain release in the free mine or quarry wall known as rock bursts Granite Commercially the term is applied to true granite some gneiss granodiorite and gabbro granites Uniformly colored granite is a highly desirable dimension stone Most of the US production comes from regions where large masses of unweathered gran ite usually intrusive bodies lie at or near the surface These criteria and a proximity to commercial markets make the folded and intruded mountains of New England the southern Piedmont province Georgia and the Carolinas and certain northcentral states Wiscon Table 55 Production of Stone in 1969 by Types of Stone in the United States Percentage of K total Type Tonnage Value Crushed stone Lmestone including dolomite 73 567 ranite 9 9 Marble 2 2 Sandstone including quartzite 3 4 dJraprock LhI439Hquot 39dalo399 10 11 100 100 Total millions 861 1326 Dimension stone Granite 37 46 Limestone including dolomite 31 13 Marble 4 13 Sandstone including quartzite 17 1 1 Slate 8 9 Other 3 3 100 39 100 Total millions 1873 99 From US Geological Survey ROCK AND STONE AS CONSTRUCTION MATERIALS 137 sin Minnesota South Dakota the major production centers in the United States Cranite quarries usually reveal the distinctive sheet jointing structure that aids the quarrying operation Fig ure S14 lndeed jointing and faulting are critical to the production of dimension stone Too much fracturing produces unusable stone too little makes for difficulties in quarrying Quarry operations are also sometimes impaired by the release of stresses caused by the mining itself On the other hand smallscale deformational structures in a competent rock will sometimes add to the ornamental value Slate The pronounced cleavage of mildly metamor phosed shale called slate made this rock a favorite con struction material in the past Sheets of slate were used as flagstones blackboards roofing shingles and billiard table tops Because of difficulties in quarrying slate requires considerable human labor for its removal Drill ing and blasting would damage the stone so sawing and splitting along the cleavage are used These difficulties have led to such great expense that slate has largely been replaced in many of its traditional uses by other materials Composition roofing has largely replaced the slate roof Nevertheless slate is still valued for its extremely high durability Most slate roofs will outlive the structures on which they are placed Moreover slate has one of the highest tensile strengths normal to the cleavage planes of any rock Sandstone Although sandstone the rock composed predominantly of sandsized quartz grains would seem to be a petrologically simple rock it actually comes in numerous varieties Graywacke contains considerable sandsized grains of rock fragments as well as much finer matrix material Arkose contains greater than 25 percent feldspar Orthoquartzite is greater than 95 percent quartz Variations in cements matrix texture and impurities all contribute to variations in the desirability of sandstone as a construction material Dimension sandstone should have a firm cement of silica or clay Calcite and iron oxide cements can lead to solution weathering or staining Porosity can also cause durability problems as discussed earlier Marble Metamorphosed limestone called marble remains a highly valued dimension stone and a source of memorial or statuary stone Precambrian Georgia marble was used for the statue of Lincoln at the Lincoln Mem orial in Washington DC The John Paul Jones Memorial in the same city is made of Vermont marble The most desirable marble is either uniformly colored or banded Because marble is composed of densely packed inter 90 Wi P SAW j 138 ROCK lTS STRENGTH DURABlLlTY AND USES locked grains it withstands exposure much more readily than limestone The major US production is from Ver mont and Georgia Crushed Stone D9 Although the production of dimension stone has declined through this century the demand for crushed stone has steadily increased Together with sand and gravel crushed stone is required for such diverse uses as road metal ballast for railroads gravel for parking lots and driveways aggregate for concrete rock fill dams and riprap Desirable characteristics of crushed quotstone for use in construction are toughness strength abrasive resistance low porosity and absorption and absence of reactive components In 1950 the value of aggregate production in the US was about 680 million By 1973 the value adjusted for inflation was over four times as great The 1973 aggregate consumption by the United States was nearly 2 billion tonnes or about 10 tonnes per person per year The US Bureau of Mines 1975 estimates that by the year 2000 the US consumption of aggregate will be 23 billion tonnes The most Commonly utilized lithologies for crushed stone in the United States are limestone and dolomite 73 percent followed by basalt and diabase 10 percent and granite 9 percent Table 55 Riprap is irregular broken stone used to protect earth embankments from erosion by waves and stream action Good riprap should have sufficient strength soundness and low water sorption The crushed stone should be angular to allow stability on sloping surfaces It should be at least 17 cm in diameter and it should have a bulk specific gravity greater than 26 to resist displace ment by waves or currents Basalt and Diabase These rk fin rained igneous rocks known commercially as ltra r0ckjare highly val ued for concrete aggregate and road material They are drilled and blasted in quarries to produce shattered stone which is crushed and screened before shipment to market This product has a very high place value so sources are located very close to markets usually within 50 km Major production comes from the basalt ows and sills that are intercalated with the Triassic Newark group in the lower Connecticut River Valley northern New Jersey and southeastern Pennsylvania The Colum bia Plateau volcanic province of Washington Oregon and Idaho also provides immense local sources of traprock Limestone Even the name limestone was derived quotquotTquot quot from the commercial use of this rock It was the material used to produce lime as discussed below Limestone includes those sedimentary rocks composed of at least 50 percent calcite and dolomite in which calcite domi 39 nates Like sandstone this rock comes in numerous l varieties that reflect complex genetic processes Lime stone is a common rock throughout the Appalachian Pla l teaus Allegheny Mountains and Mississippi River Valley I Its proximity to major commercial centers has favored its exploitation as crushed stone for road metal railroad i ballast and concrete aggregate Limestone is the most heavily used source of crushed stone for aggregate Table 55 Bates 1960 notes that more than twoand onehalf times as much crushed limestone is used for this purpose as basalt granite and I sandstone combined One reason is that limestone is far less abrasive to crushing equipment than these other common rock types However care must be taken that limestone for aggregate be uniform nonporous and free of chert organic matter and pyrite Although not as durable as some dense igneous rocks a quality lime stone usually is resistant enough for most uses of aggre j gate Sand and Gravel Q Sand and gravel accounts for the greatest tonnage of a 39 single resource material that is extracted from the earth l This material is basic to modern construction especially quotH as aggregate for concrete permeable subgrades for roads and railroads bituminous mixes and foundation J support The very pronounced place value of this resource results in a need for a close proximity of sup 3 plies to the actual construction sites Cities highway construction areas and other sites of intense demand will therefore dictate the general location and intensity of sand and gravel extraction The major sources of sand and gravel are alluvial and glacial deposits but locally beach dune and ocean sources are economically available Sand is defined as material ranging in size from 006 mm to 2 mm Gravel ranges from 2 mm to 4 mm gran ules from 4 mm to 64 mm pebbles and from 64 mm to 356 mm cobbles The detailed character of the sand and gravel is designated by gradation or sizedistribu tion curves see Chapter 6 for examples Use of Stone as Concrete Aggregate Concrete is a mixture of aggregate cement and water that hardens after mixing The Romans were pouring concrete over 2000 years ago Aggregate accounts for approximately 70 percent of concrete by volume and 80 percent by weight therefore its selection for use in i 3 3 laggregarejas follows ob 2 39quot quotquotquotquot R C Lgt 5LL owesf concrete is a very important decision Chapter 6 dis cusses several geologic sources for aggregate The American Society for Testing Materials defines inert materials which when bound together into a conglomerated mass by a matrix form concrete mastic mortar plaster etcquot Of course no geological material is completely inert and consider able geological investigation is necessary to define and locate materials that will be suitable as aggregate The texture of a material chosen to be an aggregate is perhaps its most fundamental property Engineers will generally characterize particle size distributions as grading whereas Poorly sorted wide range of particle sizes means the same as well gradedquot The precise description of sedimentary textures will be considered more fully in Chapter 6 Generally a potential material must be c ein that is free of fine particles which would include mica clay and organics These impurities could cause a weakened bond between the particle and the cementing agent Some clay minerals will also expand on wetting to pro duce spalling or cracking of the concrete If the potential material contains a predominance of particles in one size class then it may contain considerable void space Then this void space must all be filled with cement to make concrete Ideally therefore the material should be well graded in the sand and gravel range that is it should co in an even distribution oT39sizes so that finer parti cles fill the voids between the larger ones Often natural materials must be artificially screened and mixed to pro duce an ideal range of sizes to generate the strong cementaggregate bonding necessary for a strong concrete The workability of a cementaggregate mixture is another important consideration in the economics of concrete production Here particle shape will play a role Flat elongated particles tend to make the concrete seg r do not compact as easily as more spherical particles Sharp angular particles require more cement to make the mixture workable Even the surface texture of the particles is important Too smootha sur face will not promote good bonding between a pebble and the cement Soundn is another important property of aggre gate Actually this is another way of considering weath ering processes both physical and chemical Highly porgus or fractured aggregate will readilyabsorb water when being mixed to form concrete Later freezing of this enclosed water could cause expansion and failure of the enclosing mortar Aggregate must never contain nat urally weak or crumbly materials such as migaceous rocks shalefriable sandstone and clayey rocks Sulfide minerals such as pyrite and marcasite both FeS2 will an f V U 39 3 M J 391 l 1 7amp2 ROCK AND STONE AS CONSTRUCTION MATERlALS 139 oxidize and then hydrate when incorporated into con crete This process produces unsightly staining of the concrete and occasional popouts Sometimes the weak component in an otherwise sound aggregate material is merely a particle coating Coatings of clay silt calcium carbonate gypsum and oxides commonly occur on sand and gravel as a result of natural weathering pro cesses Often such coatings can be easily removed by washing and screening Concrete must be strong and durable Quartz quartz ite and many dense igneous rocks when suitably graded and washed would thus make ideal aggregate Other lithologies can also make fine aggregate but care ful study is necessary prior to a major investment The hardening of cement is a chemical process hydra tion that produces heat and releases alkalies particularly the hydroxTdes o calcium sodfum and potassium The high concentrations of alkalies reeict with certain silica rich aggregates to form silic els which absgrb water from the cement paste and eagrt osmotic pressures in the process This pressure creates tensional stresses that exceed the strength of concrete and cau ecracks and popouts of aggregates increasing the likelihood of freezethaw and water damage Chert is a highly durable rock that might be consid ered a good aggregate for concrete However chert and other cryptocrystalline silicates such as ch1lcedony and opal are some of the worst reactors in concrete Other rock types to avoid as aggregates include rhyolite andesite phyllite shale tuff and silicious limestone The problems of aggregate reactions can be reduced with the use of iow alkali cements less than 06 percent alkali but these cements are more expensive Powers and Steinour 1955 present a useful review and discus sion of the alkali reaction problem in concrete The problem is especially serious for the aggregate industry because chalcedonic quartz is relatively resistant in nat ural weathering environments and therefore is fre quently an important component of stream gravel This natural gravel would otherwise be the most important source of aggregate In areas devoid of aggregate sources artificial aggre gatecan be created by fusing locally available silt and clay from such sources as loess deposits or harbor and river dredgings The bulk density of normal aggregate is sometimes too greTo r specialized engineering applications Recent examples include the roadway of the San Fran ciscoOakland Bay Bridge and the floors and walls of the 42story Prudential Life Building in Chicago In these sit uations lightweight aggregate is used to make light weight concrete Lightweight concrete is generally con sidered to be less than 185 gcm 115 lbsft with V WW 1 140 ROCK lTS STRENGTH DURABlLlTY AND USES strengths of 14 to 350 Kgfcm 200 to 5000 psi The loss of compressive strength is compensated by the insulation and weight advantages Some types of light weight aggregates and bulk densities are given in Table 56 Lime Cement and Plaster A cement industry is one of the important ingredients in a modern industrial society Kesler 1976 notes that the annual cement production of some western European countries reaches about threequarters of a tonne per person Because cement presently costs about 20 per tonne it is usually mixed with aggregate to make concrete Lime When limestone and dolomite are heated they lose carbon dioxide CO2 and yield lime CaO CaCO3 heat CaO l CO2 CaCO3 MgCO3 heat CaO MgO l 2CO2 Production is usually accomplished b he 39 g these carbonates in a rotary kil o 1000 to 1100 C I e kiln product is used in plaster and mortar tor the con struction industry and as a source of alkali for the chem ical industry Cement The first lime cements were the natural water limes which after calcining grinding and mixing with water would set to hard cement An example is the Upper Silurian Rondout Formation of eastern New York This unit is a natural mixture of limestone clay and silica During the nineteenth century these natural water limes were the principal sources of industrial cement Today the cement industry relies on Portland cement a pulverized clinker of hydraulic calcium silicates Port land cement is manufactured from lime silica alumina and iron oxides The limestone used for Portland cement must be relatively pure it cannot contain more than 5 percent MgCO Dolomites and dolomitic limestones Table 56 Some Types of Lightweight Aggregates Unit Weight lbft kgm Perlite 612 96192 vermiculite 612 96192 Pumice 3060 480960 Expanded shale 40 70 6401120 Cinder S070 8001120 Coral 70110 11201760 Usually a relatively pure limestone is mixed must be carefully avoided The ideal raw material for Portland cement would be an impure limestone with various oxide impurities in just the right proportions ay or shale The raw material is heated to 0 er 1500 in a rotary kiln to produce a glassy clinker 34 sili cates and aluminates When mixed wquot to 4 percent gypsum the finely ground clin ecomes an excellent cementing agent for aggre e Because of high tra port costs cement plants must be located close to e desirable limestone source Mar ket consideratio dictate the placement of plants close to large cities here limestone is lacking substitutes are occasionall employed Along the Gulf Coast of Texas oyster s 394 l is used to provide lime to be mixed with local clay i roducing cement ypsum and Plaster Gypsum CaSO ZHZO is ommonly called Qfaiter of parts This material can be mixed with water and spre3EfTt then sets to a dense mass of fibrous gypsum crystals forming excellent lath and wallboard Clay Bricks and Sand lCeramics were one of the first materials that humans synthesized from their environment Prehistoric people found that the application or heat to an easily worked mixture of clay and water would reserve their designs as useful products Bricks were used as early as 6000 for construction at Jericho Davey 1961 Today the industrial uses of ceramics include various bricks drain tiles sewer pipes and architectural terra cotta Refrac to i39es are heatresistant agents that are used to line fur naces and to act as fire barriers Because of low cost and abundance many forms of clay and shale serve as raw materials for a broad spectrum of ceramic products The technology of these industrial clay products is reviewed by Brownell 1976 Clay and Shale Clay is one of the most important earth materials The term clay refers both to 1 detrital particles smaller than about 2 p and 2 clay minerals Actually clay minerals dominate in the ner size classes so there is overlap in the definitions Clay is character ized by its ability to form a pasty plastic moldable mass when mixed with water The physical properties of clay minerals will be discussed in more detail in Chapter 8 Ceramic clay products include industrial items such as brick construction tile and pipe and kiln products such as pottery chinaware porcelain and highgrade tile Bates 1960 estimates that 75 percent of all commercial clay and shale nd use as ceramics Quality kiln products Il V l 9 239i1 are usually made from clays high in the mineral kaolinite see Chapter 8 This material has the desirable proper ties of 1 high plasticity when wet and 2 low shrinkage plus high strength on drying The purer kaolin clays are also extensively used in the production of paper rubber paint plastics pharmaceuticals and chemicals United States production exceeds 2 million tonnes annually The various uses of clay fall in four categories refrac tories cement lightweigT1t aggregate and heavy clay products The uses of cement and aggregate have already been discussed The heavy industrial or struc tggal clay products are made with more common clays and shales composed of mixed clay minerals and impur ities iron oxide provides a useful flux lowering the tem perature at w IC e cay particles fuse together to form a tightly bound mass Fire clays differ from other ceramic clays in that they are required to withstand higher temperatures before melting Generally the highalumina clays kaolinite gibbsite and diaspore have the highest melting temperT at ver high refractoriness resis tance to melting coincides with low plasticity Nonplas tic fire clay called fljQ lay must be mixed with plastic clay to become useful The commonly used rotary system of drilling for petroleum requires a colloidal mud to lubricate the bit lift rock cuttings from the bottom of the hole and pro tect the hole walls An ideal material for this purpose is devitrified volcanic ash bentonite rich in the clay min eral sodiummontmorillonite Bentonite is also used as a binding agent for the sand molds employed at foundar ies as a ELuje ls and insecticides and in a host of specialized industriaTapplications Indeed new applications of clay minerals are the subject of consid erable active research Grim 1962 provides a useful review of this work Sand and Sandstone Sand or weakly cemented sand stone that is high in quartz content is most valuable for zources of foundry molds glass refractory stone filter ng medium and abrasives Some uses make certain sand iypes sufficiently valuable to give them a high unit value ioundr sand used for making molds for molten metal nust have the following properties Bates 1960 1 suf icient cohesiveness often clay bonds to hold together when moist 2 sufficient ability refractoriness to with ztand metal pouring temperatures as much as l500 C or steel 3 sufficient strength 4 suf cient permeabil y to permit gases to escape from the cooling metal and S a texture and composition that will not interact with OI metal Class sand requires an extremely high quartz content gt93 percent Usually orhoquartzites gt95 percent ROCK AND STONE AS CONSTRUCTION MATERIALS 141 quartz sands are sought Even small amounts of certain impurities such as iron oxide will discolor glass The Ordovician St Peter Sandstone of Minnesota Wiscon sin lowa Illinois and Missouri is an example of a remark ably widespread orthoquartzite that can easily be used for glass production SUMMARY Rock and stone engineering characteristics are deter mined by standard tests established by the American Society for Testing and Materials Common tests include bulk specific gravity porosity water absorption dura bility hardness abrasion toughness and soundness Stress is measured as a force per unit area that devel ops within rock to resist external forces Any resulting deformation is defined as strain Rock strength is mea sured by compression and tension tests where a force is applied to a cylinder of rock until the sample fails Many factors contribute to rock strength including tex ture structure mineralogy moisture content and degree of cementation Tensional strength of rock is typ ically only about 10 percent of the compressive strength When a linear relationship exists between stress and strain the rock acts as an elastic material Plastic mate rials do not deform until a threshold stress is exceeded The MohrCoulomb theory of failure indicates that the shear stress at failure is defined as T 0 tan ah i 70 where r critical shear stress 0 normal stress ab angle of internal friction and 70 cohesion Discon tinuities such as faults joints foliation and bedding greatly affect the strength of rock Stone used in construction is subject to weathering This is accomplished by water carbon dioxide aerosols salts and other atmospheric gases such as S0 and S03 Moisture and salts are the most damaging to stone Weathering processes include solution carbonation oxidation hydration and hydrolysis Unlike metallic ores and mineral fuels which have a high unit value rock and stone have low unit values but high place values because of high transportation costs Since 1945 there has been a shift from stone to glass concrete steel and clay products as construction mate rials US consumption of dimension stone was about 2 million tonnes in 1976 primarily granite limestone dolo mite sandstone and quartzite Crushed stone is used for road metal railroad ballast aggregate for concrete fill and riprap Limestone and dolomite are by far the most commonly used rock types Sand and gravel represent the greatest tonnage of any resource extracted from the earth The largest use is as aggregate in concrete Good aggregate should be free of fines wellgraded and not too angular nor too p 39i quot39 tr i zFl ll 142 I ROCK ITS STRENGTH DURABlLlTY AND USES rounded Finegrained silicates such as chert and opal and some silicarich igneous rocks react chemically with cement and should be avoided Clay is used in bricks tile pipe pottery and china Kaolinite clay is used primarily in ceramics bentonite is used for drilling mud and many specialized industrial uses Sand and sandstone deposits with 93 percent or more silica quartz are needed for glassmaking REFERENCES AND SUGGESTED READINGS Attevvell P B and Farmer l W 1976 Principles of engineer ing geology Chapman and Hall London 1045 p Bates R L 1960 Geology of the industrial rocks and minerals Harper amp Row New York 441 p Bieniawski Z T 1967 Mechanism of brittle fracture of rock part I theory of the fracture process lnternat Jour Rock Mechanics and Min Sci v 4 p 395407 Birkeland P W 1974 Pedology weathering and geomor phological research Oxford Univ Press New York 285 p Blackwelder E 1925 Exfoliation as a phase of rock weather ing Jour Geology v 33 p 793806 39 Brace W F 1960 An extension of the Griffith theory of frac ture to rocks Jour Geophvs Res v 69 p 34493456 Brownell W E 1976 Structural clay products SpringerVer lag New York 231 p Carroll D 1970 Rock weathering Plenum Press New York 203 p Cooke R U and Doornkamp J C 1974 Geomorphology in environmental management Oxford Univ Press London 413 p Cooke R U and Smalley l J 1968 Salt weathering in deserts Nature v 220 no 1 p 226227 Coulomb C A 1776 Essai sur une application des regles de rnaximis et minimis a quelques problemes de statitique rela tifs a l39architecture Acad Royale Sci Paris Mem Math Phys v 7 p 343382 Correns C W 1949 Growth and dissolution of crystals under linear pressure in Disc Faraday Soc No 5 Crystal growth Butterworth London p 267271 Davey N 1961 A history of building materials Camelot Press London 260 p Deere D U 1968 Geological considerations in Stagg K G and Zienkiewicz O C eds Rock mechanics in engineering practice John Wiley and Sons New York p 120 Deere D U and Miller R P 1966 Engineering classi cation and index properties for intact rock US Air Force Weapons Lab Tech Report AFWLTR65116 Kirtland Base New i4 39XlCO Dunn J R and Hudec P P 1966 Water clay and rock soundness Ohio Journal of Science v 66 p 153167 Evans l S 1970 Salt crystallization and rock weathering a review Revue de geomorphologie dynarnique v 19 no 1 p153177 in Farmer I W 1968 Engineering properties of rocks E and F N Spon Ltd London 180 p Feld l 1966 Rock as an engineering material Soiltest lnc Evanston lll 32 p Flawn P T 1970 Environmental geology Harper amp Row New York 313 p Garner L E 1976 Aggregate resource conservation in urban areas Univ Texas Bur Econ Geology Research Note 4 I2 p Gauri K L 1978 The preservation of stone scienti c Ameri can v 238 no 6 p 126136 Gilbert G K 1904 Domes and dome structures of the High Sierra Geol Soc America Bull v 15 p 2935 Goudie A Cooke R U and Evans l 1970 Experimental investigation of rock weathering by salts Area v 1 no 4quot p4248 Griffith J H 1937 Physical properties of typical American rocks lowa Engr Expt Sta Bull 131 61 p Griggs D T 1936 The factor of fatigue in rock exfoliation Jour Geology v 44 p 783796 Griggs D T 1939 Creep of rocks Jour Geoiogy v 47 p 225251 Grim R E 1962 Applied clay mineralogy McGrawHill New York 422 p Hockman A and Kessler D W 1950 Thermal and moisture expansion studies of some domestic granites US National Bureau of Standards Research Paper 2087 v 44 p 395 410 Hubbert M K 1951 Mechanical basis for certain familiar geo logic structures Geol Soc America Buii v 62 p 355 372 Hubbert M K and Rubey W W 1959 Role of fluid pres sure in mechanics of overthrust faulting Geol Soc America Bull v 70 p 115166 Jaeger J C 1964 Elast39icity fracture and flow Methuen and Company London 212 p Judd W R 1959 Effect of the elastic properties of rock on civil engineering design in symposium on rock mechanics P D Trask ed Geol Soc Amer Engineering Geology Case Histories No 3 p 5576 Keller W D 1957 The principles of chemical weathering 39 Lucas Bros Columbia Missouri 111 p Kesler S E 1976 Our nite mineral resources McGrawHill New York 120 p Kieslinger A 1967 Residual stress Summary Proc 1st Con gress lntern Rock Mechanics lll p 354357 Krynine D P and Judd W R 1957 Principles of engineering geology and geotechnics McGrawHill New York 730 p Loughnan F C 1969 Chemical weathering of the silicate min erals Elsevier New York 154 p McLintock D and Walsh J 8 1962 Friction on Griffith Cracks under compression Proc 4th Natl Congr Appl Mech Berkeley p 10151021 Mohr O C 1882 Uber die Darstellung des Spannungszu standes und des Deformationszustandes eines lltorperele mentes und uber die Answendung derselben in der Festig keitslehre Der Civilingenieur v 28 p 113156 Obert L and Duval W l 1967 Rock mechanics and the design of structures in rock John Wiley and Sons New York 650 p Ollier C D 1969 Weathering Elsevier New York 304 p Powers T C and Steinour H H 1955 An interpretation of some published researches on the aikaliaggregate reaction F G301 s39rRUcTURAL GEOLOGY I A INTRODUcTION sTRUcTURAL GEOLOGY STUDY OF DEFORMATION OF EARTH BEST IN SED ROcKs 1 ROcKs UNDER FORcEs A BRITI39LE ROCKS BREAK so FORM FAULTS B WEAK ROcKs BEND so FORM FOLDS c HIGH TEMPERATURES MELT FORM MAGMA D wHERE OccURs DEPENDS ON TEMPERATURE PRESSURE DIRECTION OF STRESS TIME B MAPPING OF FOLDS AND FAULTS 1 DIP DIRECTION THAT BED IS INCLINED 2 STRIKE RIGHT ANGLE TO DIP HORIZONTAL LINE IN THE PLANE 3 DIP ANGLE ANGLE BETWEEN HORIZONTAL AND PLANE C JOINTS FRACTURES WITHOUT MOVEMENT FROM COOLING OF MAGMA WEATHERING COMPACTION D FAULTS FRACTURES SHOWING OFFSET MOVEMENT OF ROcKs wHERE EARTH HAs BROKEN 1 EvIDENcE OF MOVEMENT A DISPLACED BEDS SLICKENSIDES B MYLONITES FAULT BRECCIA GOUGE c FAULT scARP CLIFF WHERE FAULT AT SURFACE 2 DEFINITIONS USE MINER TERMs TO LABEL BLOCKS A HANGING WALL ABOVE FAULT B FOOTwALL BELOW FAULT 3 CLASSIFICATION A DIP sLIP FAULTS MOVEMENT VERTICAL MOVEMENT PARALLEL TO DIP 1 NORMAL FAULT HANGING WALL DOWN FROM TENsION 8 PULLING APART A EXAMPLE BASIN AND RANGE 2 REVERsE FAULTS HANGING WALL UP 1 FROM cOMPREssION 2 THRUsT FAULT LONG ANGLE REVERsE FAULTs A LEWIS OVERTHRUsT MT B sTRIKE SLIP FAULTS MOVEMENT HORIZONTAL MOVEMENT PARALLEL TO sTRIKE 1 MANY FAULTs IN OREGON 2 SAN ANDREAS FAULT BEST EXAMPLE C I L 3 OFFSETS OI OcEANIc RIDGES ALsO cALLED TRANSFORM IAuLTs c OBLIOUE SLIP FAULTS COMBINATION OF DIP AND sTRIIltE SLIP MOVEMENT D HORsT AND GRABEN FAULT BOUNDED BLOCKS 1 HORST UPLAND BLOCK 2 GRABEN VALLEYS 3 USUALLY DIP SLIP MOVEMENT E FOLDING BENDING OF LAYERS 1 ORIGIN COMPRESSIVE IORcEs IN MOUNTAIN cENTERs 2 ANTICLINE UPFOLD A OLDEsT ROCK AT CENTER B sIDEvIEw AND MAP vIEw c EX PORTLAND IIILLs cOAsT RANGE D DOME SYMMETRICAL ANTIcLINE 1 EX BLACK HILLS OF sD 3 SYNCLINE DOwNIOLD A YOUNGEST ROcKs AT cENTER B SIDEVIEW AND MAP VIEW c EX WlLLAME1TE VALLEY D BASIN SYMMETRICAL SYNCLINE 1 EX TUALATIN VALLEY 4 MONOCLINE ONE FLEXURE FOLD A Ex EDGE OF ROCKIES 5 RECUMBENT FOLD FOLD on ITS SIDE A OVERTURNED BEDS F UNCONFORMITIES GAP IN GEOLOGIC HISTORY SHOWN BY A BURIED EROSION SURFACE 1 3 IMPORTANT GEOLOGIC EVENTS o UNCONFORMITY A FORMATION OF ROCKS BELOW B EROSION OF THESE ROCKS c BURIAL OF THESE ROCKS BY NEW ROCKS 2 DISCONFORMITY STRATA ABOVE AND BELOW THE UNCONFORMITY ARE PARALLEL 3 ANGULAR UNCONFORMITY LAYERS ARE NOT PARALLEL ABOVE AND BELOW THE UNCONFORMITY A 4 NONCONFORMITY SEDIMENTARY LAYERS LIE UPON MASSIVE CRYSTALLINE IGNEOUS OR METAMORPHIC ROCKS G301 LECTURE ON EARTHOUAKES I 1 DEFINITION MOVEMENTS OF EAFlTH S CRUST RESULTING WHEN A BREAK ALONG A FAULT A PER YEAR IN WORLD 1 sooooo RECORDED BUT NOT FELT 2 1ooooo FELT 3 1ooo CAUSE DAMAGE 4 so 100 ARE gt 7 wORLD SHAKERS 5 10 ARE MAJOR DISASTERS 2 DISTRIBUTION ALL OVER THE GLOBE A lt 5 EVERYWHERE B gt 5 MAINLYALONG PLATE BOUNDARIES SOMETIMES wITHIN PLATES OLD PLATE BOUNDARIES OR JUST HIGH STRESSES NEw MADRID ILLINOIS CHARLESTON SOUTH CAROLINA T ANGSHAN CHINA 3 CAUSES OF EARTHOUAKES A ULTIMATE CAUSE PRESSURE ONTO FAULT 1 PLATE TECTONICS 2 G RAVITY iii B IMMEDIATE CAUSE SUDDEN MOVEMENT OF ROCK MASSES ALONG THE FAULT C ELASTIC REBOUND THEORY 1 CRUSTAL MOVEMENTS SLOw 2 STRAIN BUILDUP 3 CRITICAL VALUE REACHED AND BREAK 4 wHERE IS THE MOVEMENT A FOCUS POINT OF FIRST RELEASE OF ENERGY ON THE FAULT B EPICENTER POINT ON SuRIACE DIRECTLY ABOVE FOCUS 5 INSTRUMENTS A SEISMOGRAPHS MEASURE MAGNITUDE AND DISTANCE AwAY OI EARTHOUAKE 1 MAGNITUDE IROM DISPLACEMENT OF S wAvE 2 DISTANCE TIME BETWEEN P a S wAvES ON SEISMOGRAM B ACCELEROGRAPHS MEASURE GROUND ACCELERATIONS 1 TO15g 6 MAGNITUDE ENERGY RELEASED FROM THE QUAKE A RICH39l39ER SCALE MAGNITUDE LOG OI AMPLITUDE PLUS AN EMPIRICAL FACTOR CHARLES RICHTER 1922 1 1 TO1o INCREMENTS OF 30 FOR ENERGY A 5 TO 6 30 x B 5TO73030 900 C IEw LARGE OUAKES RELEASE MORE THAN MANY SMALL QUAKES 2 MAX ABOUT 89 B MOMENT MAGNITUDE SAME SCALE AS RICHTER UP TO 65 AFTER IT Mm SPREADS OUT AND MAGS TO 10 G301 EARTHQUAKES II LECTURE 7 INTENSITY BASED oN DAMAGE wRoUGHT BY QUAKES A UsE MODIFIED MERGALLI scALE MAGNnUDE 1 xu DAMAGE TOTAL gt 01 2 X IGREAT 8 SERIOUS DAMAGE 70 80 3 VIIIIX CONSIDERABLE DAMAGE 62 69 4 VII SLIGHT DAMAGE TO BUILDINGS 55 68 5 V VI FELT BY ALL 49 54 6 IV FELT BY MANY 43 48 7 II III FELT BY SOME 35 42 8 I RECORDED BUT NOT FELT lt 35 B woRK BACKWARDS T0 RECREATE ORIGINAL MAGNITUDE 0 DESTRUCTION FRoM EARTHQUAKES A GRoUND MOTION COLLAPSES STRUCTURES B TSUNAMIS SEISMIC sEA wAvEs 1 USUALLY NOT UNDER 65 MAGNITUDE c LANDSLIDES ESP WHEN SLOPES WET AND STEEP D FIRE 1900 sAN FRANCISCO wAs 7590 FRoM FIRE E FAULT SCARPS CLIFF FORMED BY QUAKE RARE gt 63 F SANITARY CONDITIONS CAUSE PESTILENCE DISEASE 9 EXTENT OF DAMAGE A PROXIMITY TO FOCUS MAXIMUM NEAR IT SETBACKS B RICHTER MAGNITUDE GREATER AMOUNT MORE DAMAGE C ROCK UNDERLYING THE SITE 1 SOLID ROCK BEST STRUCTURE VIBRATES WITH ROCK 2 UNCONSOLIDATED WAVE AMPLIFICATION AND PERMANENTLY DEFORMED 3 WET SANDS LIOUEFACTION NIIGATA JAPAN D RELATIONSHIP OF VIBRATIONAL PERIOD OF STRUCTURE AND PARENT MATERIAL 1 TALL BUILDINGS LONG PERIODS gt 2 SEC 2 SHORT BUILDINGS SHORT PERIODS lt 1 SEC 3 BEDROCK AND STIFF SOILS SHORT PERIODS 4 SOFT SOILS LONG PERIODS 5 WORST WHEN SOIL AND BUILDING SIMILAR PERIODS VIOLENT SHAKING A TALL BUILDINGS NOT GOOD ON SOFT SOILS P B SHORT BUILDINGS PROBLEMS ON BEDROCK E POPULATION DENSITY F DURATION OF QUAKE 1 CALIFORNIA 20 SEC 2 OREGON SUBDUCTION QUAKE 3 MINUTES G BUILDING CODES 1 REINFORCING BARS CHIMNEY TO SLAB WOOD ROOFS WITH STRENGTH 1o SAFETY RULES A INSIDE HIDE UNDER TABLES DOORwAYS ETC FIRES OUT NO ELEVATORS AwAY FROM GLASS B OUTSIDE STAY AwAY FROM BUILDINGS 3 wIRES 11 HUMAN MADE QUAKES A FAULTS REACTIVATED WITH wATER 1 ROCKY MOUNTAIN ARSENAL DENVER 19625 2 OIL FIELDS SECONDARY OIL RECOVERY B FLUID INJECTIONS INTO SEISMIC GAPS OF FAULTS 1 SEISMIC GAP FEw QUAKES BUT LARGE ONES 2 ACTIVE AREAS LOTS OF SMALL QUAKES HOLLISTER CALIFORNIA 12 PREDICTION A SEISMIC RISK MAPS MOSTLY FROM OLD QUAKES B RECURRENCE INTERVALS BASED ON HISTORY 1 SAN ANDREAS LOCKED zONE 50 zoo YRS C PRECURSOR PHENOMENA 1 STRAIN GAUGES 2 SEISMOGRAPHS 3 TILTMETERS 4 ELECTRICAL RESISTIVITY 5 OFFSET 6 MICROPHONES 7RADON 8 ANIMALS PRECOGNITIVE BEHAVIOR 9 PEOPLE POSITIVE IONS 13 FAMOUS QUAKES A SAN FRANCISCO 1906 325 B GOOD FRIDAY ALASKA 1964 35 C NEw MADRID ILLINOIS 13111312 86 14 LAND USE PLANNING A LOCATE THE FAULTS B PAST HISTORY 1 RECURRENCE INTERVAL 2 wHEN wAS LAST ONE 3 MAXIMUM CREDIBLE EARTHQUAKE 15 4 MAXIMUM GROUND AccELERATIONs c sET BACKS FROM THE FAULT EARTHOUAIltEs IN OREGON 1 THREE sOURcEs A INTRAPLATE IN JUAN DE IUcA PLATE 74 B INTRAPLATE IN NOR3939H AMERICAN PLATE 65 c SUBDUCTION QUAKE 3 2 EVIDENCE A BURIED sOILs IN cOAsTAL MARsHEs 3 REcURRENcE INTERVAL 35o 405 YEARS 4 PAST SUBDUCTION QUAKES 300 bp soo BP 1150 BP 5 MAJOR DAMAGE FROM A GROUND AMPLIFlCA3939l0N B LIOUEIAcTION c LANDsLIDEs D TsUNAMIs G301 SLOPE STABILITY 3 LANDSLIDES LECTURE CHAPTER 4Mao 1 INTRODUCTION A MASS WASTAGE DOWNSLOPE MOVEMENT OF SOIL AND ROCK FROM GRAVITY B COLLUVIUM DEPOSIT OF MASS wASTAGE C NOT GOOD SOURCE OF AGGREGATE TOO ANGULAR TOO MANY WEAK FRAGMENTS 2 FACTORS AFFEC39I39NG DOWNSLOPE MOVEMENT A ANGLE OF REPOSE A 34 3 lta B TYPE OF MATERIAL 1 SOLID ROCK GOOD 2 CLAY AND SHALE BAD 3 SERPENTINE C INCLINATION OF BEDROCK 1 BAD DIP SLOPES PLANES OF BEDDING FOLIATION OR FAULTS PARALLEL TO SURFACE 3 quotquotlt cg 0 D FAILURE PLANES ESPECIALLY IF quotDAYLlGHTquot 1 CLAY BEDS 2 PALEOSOLS OREGON VANTAGE HORIzON 3 CHANGE IN PARENT MATERIAL A BASALT OVER GRAvELS B BASALT OVER OLDER VOLCANICS E wATER SATURATION BIGGEST CULPRIT 1 INCREASE IN MASS 2 LOwERS SHEAR STRESS 3 SOURCES OF wATER A RAINIALL B CLEARCUTTING TREES LOSS OF quotPUMPquot C LOwERING OI RESERVOIR TOO IAST F vEGETA139ION ROOTS STABILIzE SLOPES amp SURFACE COVER REDUCES OVERLAND FLOW G EARTHOUAKES GOOD TRIGGERS FOR LANDSLIDES H INCREASED SLOPE LOAD STOCKPILES STRUCTURES 1 SOLUTION REMOVE FROM TOP AND PUT AS BUTTRESS AT BOTTOM I OVERALL MAKE SURE FACTOR OF SAFETY gt 1 1 FS RESISTING FORCESDRIVING FORCES J STAGES OF FAILURES 1 SLOPE OVERSTEEPENED 2 RAIN SATURATION 3 TRIGGER EARTHQUAKE TREETHROw ETC 3 CLASSIFICATION OF LANDSLIDES A MATERIALS AND PROCESS VARNES APPROACH 1 MATERIALS ROCK DEBRIS EARTH A FALLS RAPID DESCENT OF MATERIAL VERTICALLY 1 MOSTLY ROCKFALL 2 TALUS AT BOTTOM OF SLOPE ROCKFALL A AC139lVE LOOK AT LICHEN COVER B TOPPLE LARGE SLABS FALL OVER 1 COMMON IN COLUMBIA RIVER BASALT C SLUMP FAILURE PLANE ON ROTATION 1 STRONG ROCK OVER wEAK ONE COMMON IN COHESIVE SOILS L 39gtX7 D TRANSLATIONAL SLIDE WHOLE MASS MOVES PARALLEL TO SLOPE USUALLY ON FAILURE PLANE I 13 1 1 BLOCK SLIDE WHERE MOVES AS A BLOCK 2 EXAMPLES A KANSOU CHINA 1920 180000 KILLED B GROS VENTRE WYOMING 1925 RIVER UNDERCUT SANDSTONE AND SLIDE MOVED ON SHALE INTERBED SATURATED BY SNOWMELT ON DIP SLOPE E QUICK CLAYS RAPID LIOUEFACTION OF SOILS FROM A VIBRATION RISSA SLIDE IN NORWAY ST LAWRENCE RIVER REGION OF CANADA 1 UPLIF39ED MARINE CLAYS SALT LEACHED OUT 8 VIBRATION CAUSED LIQUEFACTION OF PORES F FLOWS LIQUID LIMIT OF DEBRIS APPROACHED 1 MUDFLOWS AND DEBRIS FLOWS A MAINLY IN STREAM VALLEYS B ONLY ABOUT 30 wATER c ESPECIALLY IN ARID AND ALPINE REGIONS D MUDFLOWS SAND SILT 3 CLAY gt 30 E DEBRIS FLOWS quot quot quot quot lt 30 F TRAVEL LoNG DISTANCES FASTER THAN ILooDS IN VELOCITY LEvEES 2 EARTHFLow SLow MOVEMENT LowER WATER CONTENT ON SIDES OF SLoPES LARGE ToNGuE SHAPED DEPOSITS G DEBRIS AVALANCHES RAPID DEScENT OF DEBRIS BY FALL AND SLIDING 1 LARGE IAST MOVING OVER 300 KMHR LoNG DISTANCES 2 YUNGAY PERU 1970 22000 KILLED A 160 KMHR 3 ELM SwI12ERLAND 1331 A 310 KMHR 115 KILLED 4 ST HELENS MAY 18 1980 H CREEP SLOw IMPERCEPTIBLE MOVEMENT OI SOIL 1 SOME139lMES IN BEDROCK 2 RATES 1 MMYR TO 10 CMYR 3 CAUSES SHRINKSWELL IREEzETHAw OI PARTICLES IN THE SOIL 4 SIGNS OF EVIDENCE 4 STABILIZATION PREVENTION 3 MITIGATION OF SLOPE FAILURES A REDUCE DRIVING FORCES amp INCREASE RESISTING FORCES B REDUCE SLOPE ANGLE LOwER THAN ANGLE OF REPOSE C DRAINAGE REDUCE wATER ON SLOPE 1 SEALING SLOPE DIvERTING RUNOII PIPES D RETAINING wALLS USE wEEP HOLES 1 GABIONS wIRE MESHES E ROCKFALL PREVENTION 1 RocK BOLTING 2 SHOTCRETE 3 PROTECTIVE scREEN 4 TERRACING NOT ANY MORE 5 OREGON ROCKFALL RATING SCHEME F RECOGNIZE OLD sLIDEs 1 HUMMOCKY TERRAIN 2 DIFFERENT VEGETATION 3 uNsoRTED MATERIAL 4SCARPS 5 SLUMP suRFAcEs G VEGETA39l39lON DON T REMovE UNLESS HAVE TO H FORESIGHT AND PLANNING 1 DON T BUILD IN LANDsLIDE PRoNE AREAS 2 VAIONT DAM DIsAsTER 1091963 A 2600 KILLED 850 Flquot WALL OF WATER 3 PALOS VERDES HILLS 1957 CALIFORNIA G 301 STREAM LECTURE 1 lNTRODUC139lON A S39I39REAMS MAJOR AGENTS OF LAND REDUCTION 1 PERFORM EROSION TRANSPORTATION 8 DEPOSITION OF SEDIMENTS 2 STREAM FLOW VELOCITY AND ENERGY MEASURE OF WORK A VELOCI139ES RANGE 1 15 mph 125 kmhr 1 RECORDS 33 kmhr LYN RIVER 1952 ENGLAND 25 kmhr POTOMAC 1936 US 2 MAXIMUM VELOCITY ABOVE DEEPEST PART B FACTORS AFFECTING STREAM VELOCITY 1 GRADIENT SLOPE PROPORTIONAL TO V 2 DISCHARGE VOLUME OF WATERTIME A PROPORTIONAL TO V 3 SEDIMENT LOAD INVERSELY PROPOR39I39lONAL TO VELOCITY MORE SEDIMENT SLOWER THE VELOCITY A SUSPENDED LOAD IN SUSPENSION B BED LOAD BOUNCES ON BOTTOM C DISSOLVED CHEMICALLY DISSOLVED 1 13 OF ALL MATERIAL MOVED BY STREAMS ESPECIALLY WHERE CHEMICAL WEATHERING 4 STREAM BED SHAPE WANT SMALLEST WETTED PERIMETER FOR LEAST FRICTION AND GREATEST V A A LEAST FRICTION OTHERS MORE 5 ROUGHNESSTURBULENCE A INVERSELY PROPORTIONAL T0 VELOCITY B MANNING EQUATION 1 R cnoss SECTIONAL AREA 2 s SLOPE ROUGHNESS FACTOR 3n 3 EROSION BY STREAMS ACQUIRING LOADS MOST OF WORK DONE DURING FLOODS A HYDRAULIC ACTION UPLIFT BY BERNOULLI EFFECT ON SEDIMENT AS WATER RUSHES OVER IT B ABRASION MECHANICAL wEAR OF ROCK AGAINST ROCK IROM SEDIMENT IN STREAMS 1 MAKES POTHOLES AND PLUNGE POOLS C SOLU139lON 4 STREAM EQUILIBRIUM A LONGITUDINAL PROFILE CROSS SECTION OF RIVER FROM ORIGIN TO MOUTH B BASE LEVEL LOWER LIMIT OF EROSION IN LONGITUDINAL PROFILE REACH OF A STREAM C ULTIMATE BASE LEVEL OCEAN D COMPETENCE OF A STREAM LARGEST PARTICLES THAT A STREAM CAN CARRY DEPENDS ON VELOCITY USE THE HJULSTROM CURVE E GRADED STREAM STREAM IN EQUILIBRIUM NO MAJOR CHANGES IN EROSIONDEPOSITION F DEGRADING STREAM IN DISEQUILIBRIUM FROM EXCESS ENERGY ERoDES STREAM BoTroM 3 PICKS UP LoAD AND SLowS DowN CAUSES 1 LowER BASE LEVEL A TECToNIC UPLIFT B LowERING OF SEA LEVEL C DAM BREAKING 2 DECREASE IN LoAD A DAM BUILT so BELow DAM DEGRADES 3 INCREASE IN DISCHARGE ILooDS G AGGRADING STREAM DECREASED ENERGY so IN DISEQUILIBRIUM so DEPOSITS LoAD 1 RAISE BASE LEVEL A LAND SUBSIDING B DAM BUILT AGGRADES UPS39l39REAM C RISE IN SEA LEVEL 2 INCREASE IN LoAD A MINING DUMPING INTo STREAMS 3 DECREASE IN DISCHARGE CLIMATIC CHANGE TO DRIER CLIMATE J 5 STREAM DEPOSITIONS WHEN STREAM AGGRADES A ALLUVIUM SORTED ROUNDED SEDIMENTS FROM STREAM DEPOSITION B ALLUVIAL FAN FAN OF ALLUVIUM AT MOUNTAIN FRONT WHERE STREAM LOSES GRADIENT 8 DEPOSITS LOAD C DELTA ALLUVIUM WHERE STREAM ENTERS QUIET WATER LIKE LAKE OR OCEAN 1 SORTING HEAVIEST DROPPED FIRST 2 BEDDING TOPSET FORESET BO39I39I39OMSET 3PROBLEMS A SUBSIDENCE BAD FOR FOUNDATIONS B HIGH GROUND wATER TABLE GRAVES c ILOODS A LOT D POLLUTION OF GROUNDWATER EASY E SILTING OF RIVER CHANNELS D RIVER SAND BARS WHERE VELOCITY DECREASES 6 sTREAM TYPES A BRAIDED MULTIPLE CHANNELED sTREAM SYSTEM 1 LoosE BANK MATERIAL AGGRADING STREAM MAINLY cARRIEs MAINLY BEDLOAD CHANNELS CHANGE ACTIVELY RAPIDLY CHANGING DISCHARGE SPARSE VEGETATION HIGH WIDTH TO DEPTH RATIO B ALLUVIAL STREAMS ONE CHANNEL FINEGRAINED BANKS LOAD MAINLY SUSPENDED 1 STRAIGHT CHANNELS SINUOSITY lt 15 A S RIVER DISTANCEMAP DISTANCE 2 MEANDERING CHANNELS SINUOSITY gt 15 A STREAMS WITH BENDS NEAR BASE LEVEL B PARTS OF STREAM C ERODED ON CUTBANK AND DEPOSITED AT NEXT POINT BAR D MEANDERS MOVE LATERALLY ACROSS FLOODPLAIN E SIDECUT NOW DOWNCUT F CROSSING WORST PART FOR BOATS G OXBOW LAKE FROM CUTOFF OF MEANDER 1 VICKSBURG MISS GENERAL GRANT 2 FILL IN WITH FINES H EROSION CUTBANK DEPOSITION POINT BAR I RIVER cRoss SECTION 7 HUMANINDUCED DISEQUILIBRIUM A BLACKWATER RIVER MISSOURI 1910 1 MEANDERING RIVER FLOODS A LOT SO CORPS OF ENGINEERS CHANNELIZES RIVER S39rRAIGHTENS THE MEANDERS 2 EFFECTS OF CHANNELIZATION A CROSS SECTION ENLARGED AS MORE VELOCITY AND THEREFORE DOWNCUTl39lNG B TRIBUTARIES DOwNCUT C DEPOSITION DOWNSTREAM D DETERIORATION OF WILDLIFE HABITAT E EVENTUALLY RIVER MEANDERS AND NO FLOOD CONTROL B ASwAN DAM EGYPT ON NILE RIVER BUILT 1960 S 1 PROBLEM POOR COUNTRY NEEDS POwER AND wATER FOR IRRIGATION 3 FLOOD CONTROL 2 EFFECTS A LIFE IN MEDITERRANEAN DECREASES As LESS NUTRIENTS SARDINE INDUSTRY DIES B RISING SALINITY OF MEDITERRANEAN C BUILDUP OF SALTS IN FIELDS OF NILE amp LESS NUTRIENTS IN FIELDS FROM YEARLY FLOODS D EGYPT COASTLINE ERODING AwAY E INCREASE IN CROSS SECTION OF RIVER AND BRIDGES COLLAPSING PLAN TO BUILD SMALL DAMS TO SLOW RIVER DOWN F BILHARZIA PARASITE IN CANALS EPIDEMIC OF SCHISTOMOSAISIS G LOSING WATER TO EVAPORATION 8 STREAM TERRACES FLAT SURFACES NEXT TO RIVERS OLD 39 FLOOD PLAINS OF ALLUVIUM GOOD SOURCES OF AGGREGATE A OLDEST TERRACES AT TOP YOUNGEST AT BOTTOM 9 FLOODS TOO MUCH WATER FOR STREAM CHANNEL ABOVE BANKFUL DISCHARGE A SEE HANDOUT GEOLOGY Flooding Planning l Probability of Prediction Recunrence Interval a b C Floods of those discharges are thought to occur in x years based on historical records must be updated regularly examples l l0 year flood l0 chance per year lg2 times mean annual flood discharge 2 50 year flood about 3 times mean annual flood discharge 3 other intervals normally used l00 200 500 year floods River engineering and Management to preventreduce flood damage a b c d Floogplain Management to preventreduce flood damage a b C d improve drainage ie reduce lag time especially in urban areas where land values are so high channelization must be aware of downstream flooding and sedimentation clear vegetation in stream and on banks hydraulic redesign so river is more efficient reduce turbulence etc storm sewers reservoirdams water storage projects increase lag time watershed treatment increase lag time by increasing infiltration T permeable parking lots 2 roof storage structures 3 small dams and lakes flood retaining projects levees and dikes P C P0 39 w zoning regulations active floodway recurrence interval less than 20 years T no structures allowed keep clear for floods used for parks agriculture open space roads flood lain recurrence interval 20 l00 years l structures designed for occasional flooding first floor raised above l00 year flood level building floodproofed 2 allow temporaryportable businesses flea markets amusements etc 3 no storage of unsanitarydangerous substances low risk floodplain recurrence interval greater than lO0 years lfstructures no special designs in the structures 2 no critical land uses nuclear electricity etc no flooding area above reasonable flood level l no restrictions if people conply with these zoning plans their insurances will go down as S e mi 9 79 4 I if I 1 V K to go 00 Inc 904 Q9 currcmu I39 quotquot l G 301 COASTAL GEOLOGY SEDIMENT TRANSPORT 39 1 WINTERSUMMER MOVEMENTS OF SAND FRCM BEACH A WINTER SAND MovEs FRCM BEACH T0 BARs B WINTER BEACH 1 STEEPER NARRowER MANY OFFSHORE BARS C suMMER BEACH 1 NOW ANGLE BERM WIDE FEW BARs D THEREFORE DON39T BUILD CLOSE TO BEACH ESPECIALLY IF CHOOSE SITE IN SUMMER 2 LONGSHORE CURRENTSL39I39I39ORAL CURRENTS MOVE SEDIMENTS PARALLEL TO THE BEACH A WHY SAND PUSHED UP BEACH AT DIAGONAL DEPENDING UPON DOMINANT WIND DIRECTION 1 GRAVITY PULLS SAND DOWN PERPENDICULAR TO BEACH WHEN WATER GOES OUT B FEATURES PRODUCED BY LI39I39I39ORAL CURRENTS 1 SPIT ELONGATE RIDGE OF SAND FROM LAND TO OCEAN IN DIRECTION OF LONGSHORE DRIFT 2 BAY BARRIER SPIT ACROSS A BAY 3 TOMBOLO SAND CONNECTION BETWEEN MAINLAND AND AN ISLAND C HUMANS INTERFERING WITH LONGSHORE DRIFT CAUSE EROSION AND DEPOSITION CHANGES 1 GROIN PROJECTION OF WOODSTONE PERPENDICULAR TO LONGSHORE DRIFT A CAUSES DEPOSITION UPDRIFT B CAUSES EROSION DOWNDRIFT 2 BREAKWATER STRUCTURE PARALLEL TO SHORE THAT STOPS WAVES A DEPOSITION IN BACK OF IT DREDGE B EROSION DOWNDRIFT ON BEACH 3 JETTY GROIN AT ENTRANCE TO HARBOR A SIMILAR EROSIONDEP TO GROIN 4 DAM ON A RIVER STOPS SEDIMENT IN BACK OF DAM so LESS SEDIMENT TO BEACHES EROSION DOWNDRlFl39 3 BEACH NOURISHMENT PROGRAMS MOVE SAND ONTO BEACH THAT HAS ERODED ABOUT 1 MILLIONMILE 4 OREGON COAST 3o CELLS A HEADLANDS MAINLY FROM BASALT ILOwS B BETWEEN HEADLANDS ARE SOFrER SEDIMENTS C SAND STAYS MAINLY IN 1 CELL COMPLlCA39I39ED SEDIMENT TRANSPORT IN EACH CELL D LOTS OF SPITS E BAY OCEAN CITY ON TILLAMOOK SPIT THAT ERODED INTO OCEAN POSSIBLY FROM BUILDING OF JETTY G202 LECTURE ON GROUNDWATER CHAPTER T g 1 HYDROLOGY STUDY OF wATER A SURFACE wATER RIVERS RESERVOIRS B GROUNDWATER wATER IN SOILROCK PORES ORIGINALLY FROM RAIN AND SNOw MELT amp SOME FROM MAGMATIC SOURCES ROCKS TAKES LONG TIME TO ACCUMULATE IN SOME AREAS NON RENEWABLE RESOURCE 3 HYDROLOGIC CYCLE wATER MOVES FROM OCEAN ONTO LAND BY EVAPORATION AND PRECIPITATION 2 UNDERGROUND FLUIDS FILL PORES 1 INORGANIC FLUIDS GROUNDwATER BRINES wATER AND SALTS GEOTHERMAL STEAM GASES N He C02H2S 2 ORGANIC FLUIDS NATURAL GASES CRUDE OIL 3 GROUNDwATER OCCURRENCE 1 POROSITY PERCENTAGE OF TOTAL VOLUME NOT OCCUPIED BY SOLID MATTER RANGE FROM 1 IN SOME GRANITES TO 40 IN SANDS TO 90 IN NEW MUDS 1 39 E p A OUICKSAND HIGH POROSITY SANDS so SAND VOLUME IS LESS THAN wATER B FACTORS THAT INFLUENCE POROSITY 1 MORE UNIFORM SORTING MORE POROSITY 2 MORE ROUNDEDNESS MORE POROSITY 3 MORE CEMENT LESS POROSITY 4 IN IGNEOUSMETA ROCKS JOINTING 2 PERM EABILITY ABILITY TO TRANSMIT GROUNDwATER A MEASURED IN CLIBIC FEET OR METERS PER SEC B THE BIGGER THE vOIDS THE HIGHER THE PERM C GRAVEL HIGH PERMEABILITY D CLAYS Low PERMEABILITY EVEN THOUGH HIGH POROSITY 3 AOUICLUDE AQUITARD LAYER OF ROCK THAT HAS LOw PERMEABILITY SHALE AND CLAY ARE BEST 4 AOUIFER MATERIAL POROUS AND PERMEABLE BEST MATERIALS ARE GRAVELS SANDS LIMESTONE WITH CRACKS 3 DISTRIBUTION OF GROUNDWATER T A zONE OI AERATION vADOSE ZONE PORE SPACES NOT COMPLETELY FILLED WITH wATER wATER MOVES DOwN THROUGH THIS ZONE B zONE OF SATURATION PHREATIC ZONE PORES FILLED WITH wATER AOUIPER zONE C wATER TABLE BOUNDARY BETWEEN TWO ZONES 1 DEPTH CHANGES A RISES IN WET SEASONS amp WET CLIMATES B LOwERS IN DRY SEASONS amp DRY CLIMATE C LEVEL BALANCE BETWEEN RECHARGE AND RATE OF INPILTRATION COMPARED TO RATE OF LOSS SPRINGS STREAMS vvELLS D BOTTOM OF ZONE OI SATURATION wHERE EARTH PRESSURES SO INTENSE THEY CLOSE OII PORES AND CEMENTS FILL vOIDS 1 DEEPEST wELLS 9 km VERY HARD wATER 2 HARD wATER LOTS OF MINERALS ESP Ca Mg Fe E PERCHED WATER TABLES A SMALL AQUIFER ON AQUITARD ABOVE THE REGIONAL WATER TABLE COMMON IN PORTLAND AREA IN TROUTDALE FM 1 FORMS A SPRING AT SIDE OF HILL 4 GROUNDWATER MOVEMENT NOT STATIC GRAVITY MOVES A RATES 5 cmday TO 100 cmday B CAN TRAVEL UP TO MANY MILES AWAY C GAINING STREAMS EFFLUENT STREAMS STREAMS GAIN WATER FROM GROUNDWATER TABLE GENERALLY IN HUMID CLIMATES IF WATER TABLE FALLS BELOW STREAMBED THE STREAM DRIES UP D LOSING STREAM INFLUENT STREAM STREAM LOSES WATER TO GROUNDWATER TABLE IN ARID REGIONS NILE TIGRIS EUPHRATES RIVERS A 5 wATER WELLS A NORMAL wELLS wELL DRILLED INTO zoNE OF SATU RATION B ARTESIAN wELLS WELL wATER UNDER PRESSURE AND NORMALLY FLowS FREELY 1 AQUIFER IS CONFINED AND wATER FLOWS TO THE PRESSURE SURFACE PCTENTICMETRIC SURFACE 2 FLOWING WELL wATER COMES TO THE SURFACE 3 NONFLOWING WELL wATER COMES PARTIALLY UP THE WELL BUT A PUMP STILL NEEDED 3 DAKOTA SANDSTONE GOOD EXAMPLE C PROSPECTING FOR WELLS 1 LOOK FOR ANCIENT GRAVEL BEDS OF RIVERS NEXT TO A RIVER SEDIMENTARY ROCKS CONSULT WELL LOGS OF COUNTY 6 GEOLOGIc ROLE OF GROUNDWATIERI A CEMEN139ING AGENTS MOVES MINERALS FORMED IROM wEATHERING IN UPPER REGOLITH TO PORES LIKE SILICA CALCTE HEMATITE B GEYSERS AND HOT SPRINGS GROUNDwATER IS HEATED UP IROM cONTAcT WITH HOT ROCKS GEOTHERMAL ENERGY c wATER SOURCE D cAvES AND CAVE DEPOSITS MAINLY WHERE LIMESTONE AND MARBLE PARENT MATERIAL E KARST TOPOGRAPHY SURIAcE AND SUBSURFACE FEATURES OF LIMESTONE COUNTRY IROM DISSOLUTION 1CAVES 2 SURFACE GROOvING OI ROCKS 3 SINKHOLES COLLAPSE OF cEILINGS OI cAvES IROM LOSS OF SUPPORT MANY TIMES IROM LOwERING OF GROUNDWATER IORMS DEPRESSION IN GROUND SURIAOE 4 DISAPPEARING RIVERS SPRINGS SOLUTION VALLEYS 7 PRORLEMS FROM OVERUSE OF AQUIFERS A COASTAL AREAS SALT WATER INTRUSION FROM LOWERlNG OF GROUNDWATER TABLE FRESH WATER FLOATS OF SALT WATER 1 RA39l39O OF 401 DROP wT BY 1 FT AND SALT WATER TABLE COMES UP 40 FT B SUBSIDENCE UNCONSOLIDATED SEDIMENTS COMPACT AND GROUND SHRINKS AS REMOVE WATER COASTAL AREAS ENCROACHMENT OF SEA LIKE BAYTOWN TX 1 HOUSTON TX 2 m LAS VEGAS 1 m GREAT VALLEY CA 8 m C RECHARGE REDUCED BY 1 URBANIZATION PAVEMENT 2 DRAINING SWAMPS 7 PROBLEMS FROM OIERUSE OF AOUIFERS A COASTAL AREAS SALT wATER INTRUSION FROM LOwERING OF GROUNDWATER TABLE FRESH wATER FLOATS OF SALT wATER 1 RATIO OF 401 DROP WT BY 1 FT AND SALT WATER TABLE COMES UP 40 FT B SUBSIDENCE UNCONSOLIDATED SEDIMENTS COMPACT AND GROUND SHRINKS AS REMOVE wATER COASTAL AREAS ENCROACHMENT OF SEA LIKE BAYTOWN Tx CAUSE TOO MUCH WITH DRAwAL 1 HOUSTON Tx 2 m LAS VEGAS 1 m GREAT VALLEY CA a m PHOENIX 12 Cmyr 2 PROBLEM WITH wATER TRANSPORT SYSTEMS OPERATE ON NATURAL GRADIENT AND IT CAN BE DESTROYED O REOHARGE REDUCED BY 1 URBANIZATION PAVEMENT 2 DRAINING SWAMPS D LOWERING OF wATER TABLE RECHARGE LESS THAN wITHDRAwAL 1 UP TO 5 myr IN ARIZONA AND CALIFORNIA 2 OGALLALA FM IN TExAs AND NEw MEXICO 30 m IN 90 YEARS sEvERAL 1 ooo YRS TO RECHARGE 3 PROBLEM wITH DEEPER WELLS HARD wATER E POLLUTION OF GROUNDWATER 1 PROM SANITARY LANDIILLs NOW REOUIRE CLAY LINER BUT OLD ONES THE PROBLEM 2 SEPTIC TANKS 3 NITRATE IERTILIzERs SALTING ROADs 4 IAsTER THE RECHARGE THE IAsTER THE CONTAMNA139lON 5 IF YOU HAVE A WELL CHECK TO SEE wHAT IS UPGRADIENT OF THE WELL S CAVES AND CAVE FORMATION NATURAL CAVITY IN ROCK A LARGE ENOUGH FOR HUMAN ENTRANCE BEYOND SUNLIGHT A IN ROCKS EASILY DISSOLVED 1 LIMESTONEMARBLE MAINLY SOME GYPSUM SALTS AND OTHER EVAPORITES B FORMATION 1 SOLUTION DISSOLVING OF ROCK BY wATER ESP WITH LOTS OF ACIDS 2 CORRASION wEARING AwAY OF SIDES BY RUNNING wATER SCALLOPS 3 SEQUENCE OF EVENTS A GROUNDWATER INTO JOINTS amp DISSOLVE B SOLUTION CRACKS BECOME SMALL STREAM C SMALL STREAMS BECOME LARGE STREAMS D wATER TABLE DROPS AND CAVE DRY E SECONDARY DEPOSITION IN CAVE C SECONDARY FORMATIONS MAINLY CALCITE TRAVERTINE DEPOSITS IORM WHEN CHANGE IN PARTIAL PRESSURE AND CARBONATE ION PRECIPS 1 STALACTITES HOLLOw SPINES FROM CEILING 2 STAIAGMITES SOLID SPINES FROM GROUND 3 CALCITE COLUMN CONNECTED STALACTITES amp STALAGMITES 4 ILOwSTONES DRAPERIES ON THE wALLS D COLORS NORMALLY WHITE BUT IMPURITIES IROM IRONS AND OTHER IONS IN THE GROUNDWATER E USED AS DATING TOOLS STALAGMITES F RATES OF FORMATION DEPENDS ON GROUNDWATER DRIPPING RATE G DEEPE39ST39 BERGER CAVE FRANCE 3600 FT H LONGEST MAMMOTH KY 60 MILES Z lt UJ J C L Ll I1I L cc Q COAST RANGE rat Hr 5 34 KLAMATH quotW moLINTA1Nsquot7 J Q 0055 9 3939 CA8 CADE RANGE InuuI10 13La W lt QOL 6l DESCHUTES UMATILLA PLATEAU Id Foch S0 VVI I3 0 Lf0m5 BLUE MOUNTAINS 6Y39CH391tquot V55 WA 39 s DHYHEE PLAINS I EXPLANATION F5 50 L4 1 nuts G nooomc N DIE SIA POLITICM H000 not LATE mscousm ICI N ILl Inoclut noootu T OIDICTIOHS CHANNELS IOUNOAIIIIS oou Eng 39 IDAHO 9 V I 3 c A39I 5 eI Ta39j r4L 39239 E ADA UT H 0933rr ELarn I T Q 39 I O scnu 39 an ussxn I E 050 no 15 29 N sur39 rx 200 III Erw 39 K K PUGET CANADA 3 3 WASHIGTo rquot 39 r 39393939quot 39i5mmo OKANOGAH 39 39 8 Loet cg SE1TTLE 0 5FO 39 150 yb quot5 quot g um L gI ussouLA I 39 quotquot 39 J 39 LOBE COLUMBIA I 39 Lnnsmu an I 0 boon LLULA our D 0 D Cgt ok CASCADE RANGE f 3 E I G301 BURNS PHYSICAL GEOLOGY quotGEOLOGY OF OREGON PROVINCES 1 Blue Mountain Province NE Oregon A Cluster of Smaller Ranges elevation rises west to east Ochoco Aldrich Strawberry to Greenhorn39amp Elkhorn to Wallowa with 9 peaks gt 9000 ft B Five major suspect accreted terranes 1 most in age range of 170 270 Ma 2 oldest rocks Grindstone terrane SW of John Day 380 Ma 20039 thick of limestone 3 most rocks sedimentary volcanic amp metamorphosed sedimentary schists 4 environments of formation oceanic volcanic arc forearc basin backarc basin deep sea floor 5 two batholiths intruded 160 120 Ma in Wallowas largest in Oregon 144 and 324 square miles granites granodiorites gabbros C two volcanic periods in west of province produced andesites and rhyolites 1 44 Ma 40 Ma Clarno Fm 2 36 Ma 18 Ma John Day Fm ash and sediment deposited in basin extensive fossils of vegetation and mammals a John Day Fossil Beds National Mon 1 Palisades at Clarno Painted Hills Picture Gorge 150039 basalt amp pictographs D Pleistocene glaciations all mountains except Ochocos Wallowas 9 major glaciers with 3 over 20 miles long E Structure province rotated 65 degrees clockwise major anticline SWNE through province F Mining 34 gold from this province gold rush 1861 edges of batholiths intruded into southern terranes zone from John Day to Idaho border 1 other minerals silver copper mercury 2 Thundereggs void llings in rhyolite and tuffs at west end opals and agate state rock G Hells Canyon deepest canyon in NA 800039 175 Ma of geologica history exposed H Officers Cave longest non limestone cave in US in John Day Fm clayssilts Kimberly 2 Klamath Mountains Province SW Oregon A Collection of Mountain Ranges with 60 in California deep canyons Siskiyou Mtns highest with Mt Ashland 753039 highest drained by Rogue River B Seven Exotic Terranes accreted to NA 1 two oldest terranes in California 450Ma 2 oldest terranes at east and younger to west 3 dextral shear rotated terranes clockwise 100 degrees 4 accreted to NA 175 140 Ma uplift 20 Ma 5 Ancient environment volcanic archipelago and spreading center and deep sea floor 6 ophiolites common sequence of ma c rocks and sediments formed at ridge 39 peridotitegabbropilloW basalts sediments a pillow basalts lots of ores peridotite layer nickel and chromium 7 second oldest roclm in state 40 150 Ma C rocls sedimentary rocks low grade metamorphics to schist D cemented together 140 155 Ma 4 plutons important because concentrated minerals E Mining rich history last nickel mine in US was near Riddle 1987 closed 1851 gold rush in Jacksonville area mainly placer F Oregon Caves National Monument cave in marble of Applegate Fm 190 Ma 3 Basin and Range Province south central Oregon A northern part of 300000 square miles in US B fault block mountains horsts and grabens with normal faults at edges from extension mainly in last 10 Ma I 3 u 1 5 major horsts uplifted mountains and 5 major grabens downdropped basins 2 Hart Mountain best defined one in US C elevations 400039 to 967039 Steens Mountains D most rocks volcanic amp formed in last 20 Ma up to 10000 thick amp cover old terranes 1 16 Ma Steens basalt 10 of Columbia River Basalt huge shield volcano 6000 square miles of basalt 2 more felsic volcanoes in last 10 Ma younger from SE to NW E Nine pluvial lakes during ice ages in basins can still see shorelines dried up 11000 BP F Steens Mountains glaciated best of west G poor mining history 4 Owyhee Uplands large horst in SE Oregon A high elevation plateau dissected by Owyhee River deep canyons and well de ned drainage for being an arid region steep gradient river B 11 overlapping volcanic calderas 15 Ma 10 Ma many 15 22 miles across rhyolite magmas and tuffs C Some basalts 1 Owyhee basalts 13 12 Ma 150039 thick 2 Jordan Craters area 28 square miles of basalts 3 shield volcanoes to south of it D Mercury mining richest supply in western hemisphere Opalite Mining District 270000 asks since 1917 E Other mining uranium diatomite lter powder and kitty litter heap leach mining of gold bentonite 5 High Lava Plains Province central Oregon 50 miles wide and 150 miles long A Elevation averageswover a mile high 408039 at Harney Lake to 798439 at Paulina Peak B Dry area so poorly developed stream system C 100 eruptive centers aligned along Brothers Fault Steens to Bend 1 ages of rocks oldest at SE 96 Ma at Duck Butte to 1600 BP at Newberry get younger by going west why steepening of subduction zone 2 bimodal eruptions rst basaltic deep source and late rhyolitic ash pumice domes where crust thinning and under tension D fault origin dextral shear and clockwise rotation in last 20 million years northern end of basin and range E N ewberry Crater National Monument 1991 1 where three faults convergeBrothers 39 Sisters and Walker Rim 2 500 square miles one of largest shield volcanoes in continental US 3 Lava River cave long lava cave 4 Big Obsidian ow in crater 1600 BP F Glass Buttes 49 Ma red and black obsidian G 5 major pluvial lakes H maars and tuff rings lava intercepts Water explosive eruptions saucer shaped a Fort Rock most famous b Hole in the Ground amp Big Hole 1 Crack in the Ground 2 miles long 7039 deep amp few feet wide Green Mountain basalt edge of graben 6 Deschutes Umatilla Plateau Province A southern extension of Columbia Plateau 63000 square miles B Columbia River basalt second largest basalt province on land in the world 1 ages 17 6 Ma from tensional backarc spreading of NA plate 2 Grande Ronde group 120 ows once every 10000 years 85 of volume of CRB 165156 Ma 3 Wanapun group 154145 Ma 36 ows average once every 20000 years C Small basins on top of basalt lled with sediment eroding Cascades Dalles Fm 118 Ma Simtustus Fm 1612 Ma and Deschutes Fm 84 Ma D 4 2 Ma small volcanic cones inDeschutes and Crooked River Watersheds ex Black Butte E rotated clockvvise 10 4 Ma by 25 degrees F Warm Springs hot springs fault produced 7 Cascade Mountains Province A Western Cascades older volcanics 1 started 42 Ma 20 Ma extensive volcanism as Farallon plate subduction was 6 times rate today of Juan de Fuca by 25 Ma p subduction zone in place 2 rocks mostly andesites and some basalts 3 later stage 13 9 Ma B High Cascades 5 Ma to now volcanism to east 1 first extensive basalt volcanism 85 of High Cascades is basalt large grabens formed 2 last million years large andesitic cones formed Hood Jefferson Sisters McLaughlin C Extensive glaciation 1 highly modi ed cones Jefferson Washington Three ngered Jack Thielsen McLoughlin Broken Top North Sister 2 Less modi ed Hood 9 glaciers South Sister 5 glaciers and Bachelor Thielsen most southern glacier in Cascades D Last eruptions Bachelor 2000 BP Hood 200 BP amp area near Santiam Pass 4000 BP E 5 mining districts Western Cascades 30 mile strip parallel to high peaks galena sphalerite copper F 10 major hot springs 12 mile wide zone at contact between High Cascades and Western Cascades G Crater Lake National Park Mt Mazama 1 erupted 7000 BP caldera 400000 years old deepest lake and clearest lake in US 8 Coast Range Province A 200 miles long and 60 miles wide mountains average height 150039 highest Mary39s Peak 4097 39 B Core chain of sea mounts basalts 6253 Ma C offshore basin lled with sediments 1 southern end 5540 Ma 2 northern end 38 29 Ma D Uplift from 50 Ma to 20 Ma 1 north north plunging anticline dividing line 45 th parallel 2 south syncline E northern end Astoria Fm 20 12 Ma sediments deposited offshore and later uplifted F 12 major sand spits 7 south and 5 north G sand sheets dunes border 140 of 310 miles of coast H oil and gas Mist eld in north gas now used for storage coal near Coos Bay 1 Stacks eroded basalt ows Sea Lion Caves largest sea cave in North America 9 Willamette Valley Province A 130 miles long and 2040 miles wide B Drained by Willamette River longest north owing river in North America C by 20 Ma valley out of sea D syncline lled with sediment from Cascades and Coast Range north valley still sinking some paleosols 150039 below sea level GEOLOGY OF PORTLAND C GEOLOGY OF PORTLAND 1 COLUMBIA RIVER BASALT A MAIN ROCK OF PORTLAND B AGE 176 6 MYA 87 1716 MYA C 300 FLOwS 5 MAJOR GROUPS D UP TO 10000 Fr THICK 1000 Fl THICK IN PDX E 80000 MI2 F DOWN GORGE TO OCEAN G vANTAGE HORIZON PALEOSOL BETWEEN FLOWS 300000 YEAR OLD SOIL FROM 16 MYA RED SOURCE OF IRON IN LAKE OSwEGO 18651894 2 PORTLAND HILLS AND WlLLAMETI39E AND TUALATIN VALLEYS SYNCLINE ANTICLINE SYNCLINE 3 TROUTDALE FORMATION 10 2 MYA IN AGE A UPPER SANDSTONES MAINLY OF SEDIMENTS FROM ANCIENT CASCADES B LOWER GRAVELS FROM OLD COLUMBIA RIVER CONTAINS MICA C EXCELLENT AQUIF ER 4 BoRING LAVAS 3 MYA To FEW THOUSAND YEARS BP A LIGHT GRAY BASALTS HIGH ALUMINA B MOST coNES IN PORTLAND ARE lt 7ooooo BP c cINDER CONES MT ScoTT MT TABoR ETC D SHIELD VOLCANOES DMT SYLVANIA LARcH E DURING UPLIFT OF CASCADES F LAVA TUBES AT ST VINCENT 5 PORTLAND SILTS up To 100 FT THIcK A LoESS EoLIAN WIND DEPOSITED SILTS OF HILLS 4 PALEOSOLS B LoTS OF LANDSLIDES IN IT 6 MISSOULA FLOODS A ICE DAM BREAKS oN LAKE MISSOULA AND wATERS COME DowN COLUMBIA BASIN B BIGGEST FLOOD oN EARTH c 15300 To 12700 BP D ERoSIoN cHANNELED SCABLANDS couLEES LAKE oSwEGo SULLlVAN S GuLcH E DEPOSITION ERRATIcS ICE RAITING GHAVEL BARS MUCH OF PORTLAND E EARTHQUAKES 1 THREE SouRcES A INTRAPLATE IN JUAN DE FUCA 74 B INTRAPLATE IN NA PLATE 05 c SUBDUCTION QUAKES 3 2 EVIDENCE A BURIED SOILS IN coASTAL MARSHES 3 REcuRRENcE INTERVAL 350 450 YRS 4 PAST SUBDUCTION QUAKES 300 BP 300 BP 1150 BP 1300 BP F RADoN GAS 1 URANIUM 233 TO LEAD 200 RADoN IS INTERMEDIATE DAUGHTER GAS wITH HALF LIFE OF 33 DAYS 2 5000 30000 LUNG CANCER DEATHS YEAR 3 ROCKS THAT GENERATE GRANITE GNEISS LIMESTONE PHOSPHATES BLACK SHALE 4 TRAPPED IN BASEMENTS woRST IN PoRTLAND ON ALAMEDA RIDGE S Portland39s Landscape Setting 5 H Chapter 1 Portland39s Landscape Setting Larry W Price C 1 l m quot quot quotP 39 H quot o 13 I I2IlJquot39Equot 1 S55l 8 T 330 l P 0h ceiyed as being a 39actually situated 80 miles from the ocean in the Willamette Valley a large synclinal depression between the Cascade Mountains and the Coast Range This valley 200 miles long by 3040 miles wide slopes gently northward and is occupied by the Willamette River the longest north owing river in the continental United States Portland straddles the lower 20 miles of the Willamette until its con u ence with the Columbia The Columbia River of course rises several hundred miles to the northeast in the Canadian Rockies and transects the Cascades and Coast Range on its way to the sea In Portland both the Columbia and Willamette Rivers are within 10 feet of mean tide level and feel the daily ebb and flow of the tides In addition the presence of ships loading cranes and the hustle and bustle of dock areas give Portland an aura of the sea Sixty miles to the east is the crest of the mountains appearing as a dark green ridge in the distance except for the intermittent snow capped sentinels 83 Mt Hood The des are a major natural barrier This is expressed in many ways but perhaps most strongly through their effects on weather and climate The abundance of clouds and rain on the west side is well known This in turn produces the dense coniferquot forests for which the Pacific Northwest is so justly famous 13 I quot quot Department of Geography Portland State University The Cascades also stand as threshold and gateway to the more continental and sunny east side the Columbia plateau Blue Mountains and beyond These two features then the moun tains and the sea are part of the en vironment and ambience of Portland and yet they are both distant phenomena The Portland landscape itself may be capsulized as consisting of a broad valley floor the confluence of two rivers a longitudinally elongated ridge of hills and a spattering of extinct volcanoes see map frontis These features are a function of Portland39s location in a young orogenic region with faulting folding and volcanism all in evidence The other major factor contributing to landscape character is Portland s location near the debouchure of the Columbia River from the Cascades This great transverse passageway provides a sea level conduit between the east and west side of the mountains and is of special significance since the major events that have shaped Portland39s landscape history have come primarily from the east Curiously these include both what are among the largest lavaand water floods on the face of the earth This essay begins and ends with these spectacular but disparate events COLUMBIA RIVER BASALT The primary rocllt type of the Portland area is Columbia River basalt The his t 6 I Portland39s Landscape Setting 0 I I h I T l 1 F 124 20 1 WASHINGTON gt 9 0 l Seallle K 39 I 48 4 L Figure 11 Generalized distribution of the Columbia River Basalt including all of the indi vidual flows from Tolan Beeson and Vogt 1984 p 90 tory of the fissure ows which compose this material is extremely interesting and great strides have been made in recent years in working out their dif ferentiation timing and movement Hooper 1982 Swanson et al 1979 They represent a great volcanic pile of ood lavas erupted from northnorth west trending vents to the east of the Cascades some 176 million years ago They cover an area of 80000 square miles stretching from Idaho to the Paci c Ocean with their finest develop ment occurring on the Columbia Plateau in northeastern Oregon and southeastern Washington Figure 11 In places the basalt reaches depths of over 10000 feet Reidel et al 1982 but thicknesses decrease to the west md in Portland they are only about 1000 feet thick Not all of the flows reached western Dregon The ancient Cascades existed ii the time as did the ancestral Columbia her and thewestward flowing lavas ould only cross the Cascades through this gap Beeson and Moran 1979 There has been much speculation about the location of ancestral channels of the Columbia River Hodge 1938 Lowry and Baldwin 1952 Recent analysis of the flows through paleomagnetic polarity and chemical composition indicates that while there have been substantial changes in channel location during the last 15 million years the river has remained within 50 miles of its present location in the Cas cades generally to the south of the present Columbia River Gorge Fecht Reidel and Tallman 1985 Figure 11 Evidence from intercanyon ows beneath the present location of Mt Hood suggests that the river formerly flowed to the southwest emptying into the central Oregon coast near Lincoln City Tolan Beeson and Vogt 1982 p 92 Its channel was forced northward by later ows until it reached its present locationThis gives rise to the intriguing idea that many of the headlands on the Oregon Coast are actually intercanyon flows representing ancient Columbia River channels Allen 1984 The individual flows of the basalt average about 50 feet in thickness Between flows there were often long intervals in which weathering and ero sion occurred Consequently many of the flows overlie one another uncon formably In some cases weathering horizons and soils are found One of the most extensive of these is the Van tage horizon named for a town in central Washington where up to 200 species of tree fossils are found the Ginko being one of the more common In the Portland area the Vantage hori zon is thin and discontinuous but fossil trees up to six feet in diameter have been discovered in it Diller 1896 pp 508511 The chief significance of the Vantage horizon quotin Portland is that it A I ortland s Landscape Setting 7 quotl39 r I 39 395 I 39 I 39 En139 l39 39 quot39 quotII 39 I i ii ligure 12 Oblique aerial View to the Highway 26 Bridges shown westnorthwest of downtown from left to right are Mar Portland and the Portland quam Hawthome Morrison Hills anticline The sharp Burnside Steel and Broad break in slope where the way The photo was taken Portland Hills fault is in 1969 so the Fremont thought to exist can be seen Bridge to the north of the quot1l l39Rquot39 39 along the right margin of the hills The traverse valley across the Portland Hills in upper left of the photo is the pathfollowed by U S Broadway Bridge is not yet constructed copyright photo Delano Photo graphics Inc Cwntains limonite strongly weathered mm oxide clay These low quality de l Hits were heavily mined in the Lake l 390 39o area fromgl865 to 1894 Hotz 1955 p 91 Iron Mountain about two miles west of Lake Oswego now a site of exclusive housing developments was a major source of the iron ore 51 J I 8 l Portland39s Landscape Setting Elevation 2000 1500 LOGO Quaternary j f 39 5 amy i W quotquot391quot 3939 39 Troutdale rtquot 3 39939 quot 39 39 A 1 kl on I quotf39l rF39hquotfmnquotH 39 quotquot m r um I 1394 u mummml II I 39 II 395 1 m quotquot 39139f39a nmaruoal 39 Llul m39ruquot nrnllrrv39lI3939quot39l39llatu 1 Iquot nil n u M nu 439quot M1 Wm I gm 1 g I 39 U I mmJrgtq l 39H 39 aa quotm39 Ilf39lIm 3 39 2 000 Feet quot quotquotquotquot555 I1quot39lt39trrvi i35 A uvium J 39I t t Y Z 3939 tZ 39blmrjquotquot1 tmmquotr 3939 m1 rn rgr lmmL P V J f 1It39upv n39 p rn quotWtnfunn 39l39llH rnIi HmI 39quotvr Wquot 1 171 H11 Imu gr ga 139 q39 Geologic cross section of the Portland Hills showing anticli nal structure as well as the location of the Portland Hills Fault after Balsillie and Ben son 1971 p 116 Figure 13 Remains of the smelter built of large basaltic blocks still stand in George Rogers Park by the river in Lake Oswego The Columbia River basalt in the Portland area has been strongly folded and faulted as well as dissected by ero sion The most prominent structural feature is the Portland Hills Tualatin Mountains an elongated ridge 500 1000 feet high and 20 miles long by three miles wide trending northwesterly along the western margin of the central business district Figure 12 The Portland Hills is basically an anticline with syn clinal counterparts in east Portland and the Tualatin Valley to the west buried by as much as 1500 feet of sediments Schlicker and Deacon 1967 p 17 The east side of the Portland Hills rises abruptly from the valley floor as an impressive escarpment along a straight and sharp boundary which may be a fault Figure 13 The evidence for a fault is not conclusive and the primary geologic maps of the area do not show it Treasher 1942 Trimble 1963 Cir cumstantial evidence is strong how ever and several workers have argued for its presence Schlicker and Deacon 1967 Balsillie and Benson 1971 Schmela and Palmer 1972 Seismic activityin the Portland area is relatively low but earthquakes do occasionally occur and it is assumed that the Portland Hills fault is active Dehlinger et al 1963 Schlicker Deacon and Twelker 1964 Heinrichs and Pietrafesa 1968 Given its presumed location directly under the city center Portland State Univer sity and the Trojan Nuclear Power Plant at Rainier its disposition is clearly more than academic The Portland Hills is the site for many of the more exclusive and pre stigious housing areas of Portland as well as Washington Park with the Zoo open air water reservoirs Oregon Museum of Science and Industry Rose Gardens and Japanese Gardens North of Washington Park are Macleay and Forest Parks a complex of more or less natural areas of forests and trails forming one of the largest urban parks in the United States TROUTDALE FORMATION The Columbia River basalt is locally overlain by up to 1500 feet of late Pliocene or early Pleistocene sandstone and gravels Hodge 1938 This de posit known as the Troutdale Forma tion occurs as a huge fan localized near the debouchure of the Columbia River from the Cascades and consists of two differentfacies the upper facies is primarily sandstone of locally de rived basaltic materials presumably eroded from the ancient Cascades The lower member consists of gravels con taining abundant cobbles of quartzite 1 o4 iists and granites which tie it to the lttral Columbia River and source guns to the east since the volcanic scades do not contain crystalline iterials In addition the restriction these deposits to the northern llamette Valley and Columbia River i39gL39 indicates that the ancestral Col lbl River was near to its present ation in Pliocene time Tolan and eson 1984 The age of the Troutdale rmation is estimated at between ten two million years with deposition urring throughout this period ilan Beeson and Vogt 1984 p 93 e type locality for the deposit is near mtdale Oregon along the east side the Sandy River Although buried der much of Portland and providing excellent aquifer it outcrops occa nally especially where it has been faulted or folded as along the east e of the Portland Hills RING LAVAS If one were to stand on a promi nce in the Portland Hills and look y5tward over the city the general im Fression would be that of a low plain ng gently to the east occasionally errupted by isolated conical hills sse are ancient volcanoes that ipted locally at the close of the Trout quote deposition from six million to 39haps a few hundred thousand years i They consist of both cinder cones i shield volcanoes and are composed An excellent exposure of Troutdale gravels may be seen near downtown Portland on N W Cornell Road just before the first tunnel at about N W 34th Park immediately before the tunnel and walk up the path on the south side of the road which leads to an old gravel quarry site The material consists of well rounded cable sized and strongly weathered gravel clasts of basalt granite marble and quartz Portland39s Landscape Setting 9 9 of highalumina basalts similar in com position to the High Cascade vol canoes eg Mt Hood In fact they may have been initiated by the uplift and emplacement of the High Cascades Tolan Beeson and Vogt 1984 p 93 Their local distribution is restricted to a 3040 square mile area in the lower Willamette Valley and foothills of the Cascades As many as 90 individual vents and flows have been identified Figure 14 The material of these volcanoes is known as Boring lavas from their occur rence near the town of Boring Oregon Treasher 1942 The lava is characteris tically light gray rather than dark gray or black as is more typical of the Col umbia River basalts and its structure tends to be massive or blocky rather than columnar Allen 1975 p 149 The Boring lavas were apparently quite viscous because they did not flow far from their vents Many of the iso lated hills formed by these eruptions are well known local landmarks eg Mount Scott Rocky Butte Mount Tabor Kelly Butte and Mount Syl vania The best and most accessible example of their volcanic character is Mount Tabor where a small vent has been excavated so the throat and dip ping cinder beds are nicely displayed Erosion has strongly modified the shape of some of the volcanoes Rocky Butte for example was directly in the path of the Missoula ood waters that 2 Mt Tabor is located off S E Belmont and 69th Street Turn right at the park entrance and drive about two blocks The excavation reveals the internal charac teristics of the volcanic vent beautifully it is well worth the trip to see it A small sign erected by the Geological Society of Oregon Country states that Portland is the only city in the United States with a quotvolcano within its limits 10 Portland39s Landscape Setting Vancouver Lake 400 39 P ROCKY BUTT PORTLAND 440 I 39 UT0NE QCHAMBERLMN QLARCH M1 HILL MT TABOR KELLY BUTTE HGRESHNI 1 E I anvsnrou 5 5 5 quotoz 0 39 39o MI 4 O N Wquot osweco SCOTT 90 E C Became at 39 Q NM Baumcrwoo o xi omzcou l H Cl 4 V ii i N g c vw E Eqiggf 39 ESTACADA E 5 cmaav 9 1 HIGHLAND BUTTE BEACON 39 9 soc 0 Vhm uu 5 AAA 39igure14 Distribution of Boring volcanoes Three are consi dered to be shield volcanoes Larch Mt Mt Sylvania and Highland Butte while the rest are primarily cinder cones modi ed from Allen 1979 p 75 oursed through the Columbia Gorge t the end of the last ice age Its east acing slope has been cut into a vertical luff and there is a large depression or othole to its lee where the waters oiled around the obstacle Bretz 1925 255 Rocky Butte also has Troutdale ravels exposed in its sides Apparently we eruption encapsulated and lifted we gravels since they are exposed at 1 elevation of about 500 feet above ie surrounding surface Trimble l963 41 Allen 1975 has pointed out that the volcanic vents are approximately aligned with other structural features in the area For example the entire west side of the Portland Hills is built of Boring lavas from vents located near the axis of the anticline Figure 14 The lavas flowed predominantly to the west An interesting feature here is the presence of lava tubes Several buried caves and tunnels have been discovered and are of engineering concern since 3 A visit to the top of Rocky Butte is strongly recommended This is perhaps the best place in Portland to have a 360 degree panorama of the city Columbia River Boring volcanoes and the West Hills with the central business district nestled at their base Take Fremont Street of N E 82nd Avenue to 91st Avenue A where you turn north and follow road to the summit 39 A Portland39s Landscape Setting I 11 LOCATION MAP quotl EXPLANATION E3 PORILAND MILL SILI 0 SAMPLE KOCATID 55 MAP Alfal Inus I39 PCR39 a 5 mus areas of Portland Principal Hills Silt Base map is 1250000 raised relief map of Portland Vancou39er area mod ified from Lentz 1981 p 1 hey underlie important surface struc ures such as N W Barnes Road and st Vincent Hospital Allen 1974 ORTLAND HILLS SILT Elevations above 600 feet in the ortland Hills are commonly blanketed vith a massive silty deposit reaching iepths of up to 100 feet Figure 15 he origin of this material known as he Portland Hills Silt is somewhat uzzling because it contains scattered ebbles and stratified bedding but it is it above know water levels for the Jgion Earlier workers interpreted it being water deposited Diller 1896 Uwry and Baldwin 1952 but most rcent investigations have argued for H aeolian origin Theisen 1958 heisen and Knox 1959 Trimble 1968 entz 1981 i 2 The silt is thickest near the Columbia River and thins with distance away It occurs on elevated terrain southeast of Portland between Gresham and Boring and in the Mt Scott area south to the Clackamas County line see map frontis Its best development however is in the Portland Hills where it is thickest on north and northeast slopes facing the river Figure 15 It thins to less than 50 feet on the west side of the Portland hills and by the Chehalem Mountains 18 miles to the southwest it is only 8 to 10 feet thick This pro vides an impressive rate of decrease in depth of five feet per mile Even more spectacularly the silt thins from 10 feet in the Chehalem Mountains to zero in only four miles to the southwest in the Red Hills of Dundee Parsons 1981 For this reason Parsons 1981 is reluc tant to abandon the idea of a water origin for the silt he would apparently explain its elevated location by tectonic displacement 39 39 Most people howeverconsider the 12 Portland39s Landscape Setting 0 VANCOUVER 1 CANADA gt 3 wAsHING iquotc3 quot 39 Tquot quot w39i6Ti39T7nTiiAquot quotgt ommocau 39 39 5 n T LOBE lg Ocgo ap I 39L BET I 39 liITgSEOULA tquot I f g PR c K Iquot G K life oeoisc I i 0 Y EXPLANATION N K I m PLEISTOCENE FLOODING T 5 1 LAKES CALIFORNI quotquotquotquotquotquot39 39 quot39 39quot 3939 39 39quotquotquot E FLOODIHG 2 NEVADA UT 6 FLOOD now oinccnons r LATE mscousm Ia 39 SCALE en newsea CHMINELS 5 39 3939quot2 quotquot 5 POLITICAL nouumnizs p IOD 200 in 0Q 3 Outline of the Missoula Flood Glacial Lake Missoula in eastern Montana was blocked by lobe of the Conti nental glacier Eventually the ice dam was breached and the water surged west ward across the Columbia Plateau Where constrictions existed eg Wallula Gap or The Dalles the water was backed up as temporary lakes A large lake also formed in the Willamette Val ley While this is shown as a single event in actualit39 it occurred a number of times from Baker and Bunker 1985 p 2 Figure 16 Portland Hills silt to be wind deposited loess The material contains large amounts of quartz and mica which could only have come from distant sources to the east of the Cascades The Columbia River floodplain was the immediate source of the deposit since particle size diminishes and its depth thins with distance from the river Unlike most loess the silt is noncalcareous Theisen 1958 p 30 Lentz 1981 has identified up to four ancient soil horizons in the loess and he correlates them with the glacial periods This places the silt at from 700000 to 34000 years BP The wind waseasterly for its deposition whereas the modern wind is prevailingly wes terly Recent pollen investigations in the Portland area indicate cooler drier conditions during the glacial periods Barnosky 1984 Such conditions were undoubtedly the result of the greater impact of continentality carried by strong east winds through the Columbia Gorge The Portland Hills silt is an im portant factor in local land use and engineering since it becomes very un stable when wet Schlicker and Deacon a 39 i Aquot 1 ii I quot771 E 1967 p 49 Landslides mudflows and slumps are all common on steep areas in the Portland Hills where expen 3Ve homes are located This becomes ggpecially critical in midwinter after geveral days of rain have saturated the and The silt also has low permeability md is not good for installation of septic anks and drain elds VHSSOULA IquotLOODS Except for the folded and faulted tructures and the scattered volcanoes arotruding from the valley floor much f Portland39s landscape is composed of mconsolidated sand and gravel These leposits occur as gently sloping to at urfaces at multiple levels in the form f terraces These features can best be sen in east Portland As one proceeds way from the Columbia or Willamette ivers he is faced with a series of marked rises in altitude interspersed 39ith broader treads like giant stair eps The highest level occurs between 75400 feet above sea level Consider g a maximum ood stage of 50 or en 100 feet for the river the origin of 358 deposits quotbecomes extremely in resting Clearly they are not related the modern river The first explanation for the elevated eposits was suggested by Oregon39s emier geologist Thomas Condon ho attributed the gravels to river de wsition in a great impoundment used by formerly higher sea levels in hat he called Willamette Sound ondon 1871 Although this interpre quotion stood for a number of years are were problems with it The sedi ants contained occasional large ulders reaching seven feet or more diameter including some composed granite Suchquot erratics were also own to occur at elevated positions lng the Columbia RiverGorge and Portland s Landscape Setting 13 into eastern Oregon and Washington Based on his marine perspective Con don explained the erratics as being ice rafted from the Straits of Juan de Fuca and the coast of British Columbia This required rockladen icebergs to travel southward along the Pacific coast and then 60 miles up Willamette Soundquot as well as through the Columbia Gorge into eastern Oregon and Washington Condon 1902 p 63 Later workers most notably Har lan Bretz thought that the erratics came not from the coast but the interior of Washington and Idaho Bretz 1919 p 502 called the impounded sedi ments quotthe Portland Delta Based on his work on the Channeled Scabland of east central Washington Bretz post ulated a huge ood of catastrophic proportions sweeping through the Col umbia River Valley Bretz 1925 This flood actually floods has had more impact on the Columbia Gorge and Wil lamette Valley than any other event in recent geologic time In order to under stand the local landscape one must be cognizant of these spectacular events Figure 16 That such floods occurred is now ac cepted as common place but in the 1920 s it was considered an outrageous hypothesis Baker 1978 Bretz was confronted in eastern Washington by a vast network of dry canyons or coulees cut deeply into the plateau These formed a huge anastomosing and de ndritic drainage system where the loess and basalt had been strongly stripped and scoured creating in Bretz s aphorism a channeled scablandquot Bretz 1923 p 618 In all 2800 square miles of the region had been scoured into the basalt and 900 square miles were buried under depositional materials Bretz 1928 p 446 Although Bretz was faced on all 14 39 l Portland39s Landscape Setting sides by strong arguments of how these features could have been created by ordinary events he was convinced that their origin could only be explained by a relatively brief but enormous ood Many leading geologists at the time considered his concept a return to catastrophism Without presenting all of the evidence he marshalled in favor of the ood suffice it to say that the theory is now almost universally ac cepted The source of the oods was eventu ally pinpointed in western Montana where the advancing continental ice had blocked the valley of the Clark Fork River to a height of 1000 feet so its drainage could not escape A lake 250 miles long and 2000 feet deep Gla cial Lake Missoula developed behind the ice dam Pardee 1942 The glacial dam eventually failed allowing up to 500 cubic miles of water to surge south westward across northern Idaho and the Columbia Plateau creating the channeled scabland Figure 16 The onrushing water encountered constrictions in its path at Wallula Gap near the OregonWashington border where the Columbia River cuts across the Horse Heaven anticline and at The Dalles where the Columbia Gorge penetrates the Cascades In both cases h were formed The water level at The Dalles just 90 niles east of Portland was 1100 feet above sea level whereas in the Portland irea the water level was 400 feet This arovides a gradient of 700 feet in 90 niles or 75 feet per mile One can only magine the velocity and force of such torrent Once beyond the Gorge the water ither entered into a higher sea level or pread laterally and filled the Willamette alley if the latter case is true it is oinewhat puzzling why it should do so since there is no obvious constriction in the Columbia River valley below Portland as in the other cases men tioned Bretz thought the ocean was 350 feet above present sea level This would have allowed for the construc tion of the Portland Delta which he considered to have been deposited sub aqueously with the river being 100 feet deep above this surface when it was built Bretz 1925 p 212 A more re cent proponent of a higher sea level as a cause of impoundment but not for catastrophic ooding was Lowry and Baldwin 1952 The other major interpretation is that the ood waters themselves were suffi cient to temporarily inundate the valley Allison 1935 stressed the importance of icebergs in transporting erractics into the valley and thought that a huge ice jam might have caused the impound ment Trimble 1963 also argued against a higher sea level pointing out that late Pleistocene sea level rises of the orderrequiredhave not been re ported from other parts of the world Also the time of ponding coincided with the glacial maxima when sea levels should have been lower not higher This is given support by the discovery of a 300 feet deep channel underlying the present Columbia River in east Portland cut during the late Pleistocene when sea level was lower and backfilled with sand as sea level rose during the Holocene A wood sample taken from the sediments at a depth of 200300 feet yielded a C14 date of 8910 or 115 years Hoffstetter 1984 p 65 Trimble39s interpretation for the cause of ponding was hydraulic damming whereby more water entered the valley system than was able to escape through the restriction Trimble 1963 p 65 The narrowest point in the channel below Portland isbetween Kalama and Jr Carrolls Washington 35 miles down stream where the channel is 18 miles wide at an elevation of 350 feet The amount of water required for such an opening to serve as a constriction so water would rise to an elevation of 400 feet throughout the Willamette Valley for several days or weeks boggles the mind The resolution as to which major interpretation is correct continues to elude us and yet it is essential for working out the details on how the Portland landscape was created The answer may lie in information still un covered such as in the various ponded deposits or in the deep sea sediments of the Astoria fan Bretz 1969 p 541 Griggs et al 1970 By whatever mechanism evidence is clear that there was a huge impond ment of water in the Willamette Valley reaching 125 miles to the south slightly beyond the town of Eugene The maximum height of the water was 400 feet above sea level as testified by a number of large icerafted erractics found throughout the valley up to that altitude Allison 1935 A classic example can be seen southwest of Portland on the Paci c Highway between McMinnville and Sheridan The floor of the Willamette Valley is almost entirely covered by gravel sand silt and clay Maximum depth of the deposits under Portland is 250 feet but at most localities the depth is 100 feet or less The deposits thin to about 30 feet farther south in the valley Trimble 1963 p 62 One of the most dominant characteristics of the gravels is steeply dipping forset beds formed as the high velocity water flowed into calmer water The beds dip mainly to the west and south indicating direction of water movement Particle size also decreases away from the Columbia Gorge reflecting diminishing energy levels as the sedi Portland39s Landscape Setting 15 ments were deposited into the ponded water Trimble 1963 p 59 considers the material as lacustrine since deltaic deposits are only part of the total pic ture with much of the alluviation taking place in slack water five distinct terrace levels occur in the Portland area lnnorth Portland there is a clearly distinguishable level at about 150 feet above sea level The campus of the University of Portland and Willamette Boulevard occurs on this planarlike surface Well marked terraces also occur at 200 250 290 and 330 feet above sea level in east Portland although the exact elevation varies slightly from place to place This is be cause the surfaces had original slope to them they have been modified by ero sion since and they may have under gone differential uplift from tectonic processes Nevertheless the terraces are marked features of the landscape and can be seen on virtually any eastwest street leading away from the Willamette River All five levels are beautifully dis played on N E Glisan Street which runs halfway between Rocky Butte and Mt Tabor Although the terraces are fundamen tally depositional features there is also considerable evidence of erosion As the debrisladen ood waters surged from place to place in the valley and when the impounded water eventually began to drain both bedrock and de positional surfaces were scoured and eroded One path of the flood waters the northwest through Vancouver Washington where a channel 50 feet deep and several miles long was cut in the gravel Lackamas Lake is located near the eastern edge of this channel Another broad erosional swath was cut to the southwest in a line extending from Rocky Butte and Mt Tabor to Lake Oswego One may see evidence yr 3 1 3 1 7u c uurxu pi isu FF H 16 39 Portland39s Landscape Setting 2 of this on the Mt Tabor 124000 USGS Topographic map where numerous elongated hachured contour lines exist on the elevated terrace surfaces Sullivan Gulch a dry channel where the presrent I84 freeway and rapid transit system MAX is located was also cut into the gravel As the water moved to the south it gouged the narrows at Oregon City stripping surfaces to bedrock and creating patches of scabland extending southwestward from West Linn to the Tualatin Valley Stauffer 1956 p 22 The water poured through the Lake Oswego Gap lpnd scoured out giant potholes and depressions Much of the material erodecl from Lake Oswego was deposited in a fan to the southwest in the TualatinDu39rham Cipole area Many gravel pits are located in this region Evidence that the water came from the west is westward dipping for set beds plus the presence of limonite pebbles in the gravels similar to those found at Iron Mountain near Lake Oswego Lowry and Baldwin 1952 p 20 Immediately to the south near the town of Sherwood is a low drainage divide betweenl the Tualatin Valley and the Willamette Valley This area known as the Tonquin scabland is a miniature replica of what exists in the Columbia Basin of northeast Washington There is an elongated north south complex of channels scoured and plucked so that virtually no soil or vegetation exists in many areas It is thought to have been created when water from the Tualatin Valley spilled southward into the Wil lamette Valley Stauffer 1956 Allison 1978 p 194 The terraces provide a tremendous number of unanswered questions as to their origin and evolution It is known that the highest terraces are the oldest and the lowest the youngest This is proved by depth of weathering and soil development on the different surfaces Trimble 1963 Parsons 1982 But they have all presumably been modified by floods subsequent to the one in which they were deposited In addition there is a distinctly younger deposit of sand and silt disconformably overlying the terrace surfaces This material ranges from a veneer to over 100 feet in depth and occasionally occurs in channels eroded in the earlier fill Trimble 1963 Allison 1978 p 196 There has been considerable specula tion as to the age timing extent and number of oods Bretz initially post ulated a single huge ood later he ex panded this to seven or more floods Bretz et a1 1956 Glenn 1965 and Waitt 1980 presented evidence for 40 floods Most recently a study has been published claiming evidence for 89 floods Atwater 1986 Exactly how each of these relate to one another is extremely difficult to unravel Baker and Bunker 1985 Allison 1978 be lieved that the events were of a two fold nature First came a series of smaller floods from the multiple breaching of the glacial dam for Lake Missoula The water was ponded in the Willamette Valley and flood deposits were laid down Eventually as the land uplifted and the Columbia River became entrenched these surfaces were left as terraces Later came the big bore a much larger single ood which was primarily ero sional Allison 1978 p 179 It was this ood Allison argued that eroded the upper terrace surfaces cut Sullivan Gulch and the channel now occupied by Lackamas Lake scoured through the gap at Oregon City and Lake Oswego and deposited the top coating of younger gravels disconformably on the Older cut and fill surfaces This theory provides a good working 139p0ll1BSlS as to the processes involved but the exact mechanisms for the im placement of the terraces and evolution of the various features have not been worked out We do not even know the exact ages of the various surfaces The date of the last ood however has been well established at about 13000 years ago Mullineaux et al 1978 Con sequently Holocene and recent modifica tions to the surfaces have come about under essentially subaerial conditions Stream dissection aeolian processes mass wasting and soil development have all left their mark on the modern landscape Man too has brought about modifications Nevertheless the surfaces retain much of their original character and ample evidence remains for land form students of tomorrow to analyze and interpret This is particularly true since much of the Portland area is now occupied by residential or commercial activities with many restrictions through land use policies to prevent the develop ment of new quarries It is interesting that in spite of its abundance sand and gravel in the Portland area is an acutely limited resource As a matter of fact most aggregate products are now either crushed or transported in from pits up or down valley Gray Allen and Mack 1978 In conclusion Portland has been the scene of a series of spectacular geologic events ltbegan with huge lava oods issuing intermittently from eastern Oregon through the Columbia Gorge to inundate the area Over time these ows were folded faulted buried under sedi ments penetrated by local volcanoes weathered and eroded Most recently another series of oods originated to the east of the mountains this time consisting of vast amounts of water choked with rock debris and ice these torrents surged through the Portland areacut Portland39s Landscape Setting 17 ting andtilling to create the terraced landscape we now see The overwhelm ing impression that one is Ieft with after reviewing these events is the great power and scale at which they oper ated They can be described only by superlatives Portland has indeed had a dynamic and exciting geomorphic past REFERENCES Allen J E 1974 quotThe Catlin Gable Lava Tubesquot Ore Bin Vol 36 No 9 pp 149 155 1975 quotVolcanoes of the Portland Area Oregon Ore Bin Vol 37 No 9 pp 145157 T 1979 The Magnificent Gateway Forest Grove OR Timber Press 144 pp j 1984 Coast Headlands Linked to Eastern Oregon Lava Flowsquot The Oregonian Portland Newspaper January 26 1984 in column entitled quotTime Travel 39 Allison I S 1935 quotGlacial Erractics in Wil lamette Valley Geological Society America Bulletin Vol 46 pp 615632 Allison I S 1978 quotLate Pleistocene Sedi ments and Floods in the Willamette Val ley Ore Bin Vol 40 No 11 8 12 pp 177202 Atwater Brian F 1986 Pleistocene Glacial Lake Deposits of the Sanpoil River Val ley Northeastern Washington llS Geological Survey Bulletin 1661 39 pp Baker V R 1978 The Spokane Flood Con troversy and the Martian Outflow Chan nels Science Vol 202 No 4373 pp 12491256 Baker Victor B and Russell C Bunker 1985 Cataclysmic Late Pleistocene Flooding from Glacial Lake Missoula A Review Quaternary Science Reviews 41 41 Balsille J H and G T Benson 1971 Evi dence for the Portland Hills Fault Ore Bin Vol 33 pp 109118 Barnosky C W 1984 quotLate Pleistocene and Early Holocene Environmental His tory of USA Canadian lournal Earth Science Vol 21 pp 619629 Southwestern Washington 18 Portland39s Landscape Setting Beeson M 11 and M R Moran 1979 quotColumbia River Basalt Group Stratigraphy in Western Oregon Oregon Geology Vol No 41 No 1 pp 1114 Bretz J H 1919 The Late Pleistocene Submergence in the Columbia Valley of Oregon and Washington Journal Geology Vol 27 pp 489506 1923 quotThe Channeled Scabland of the Columbia Plateau Journal Geology Vol 31 pp 617649 1925 quotThe Spokane Flood Beyond the Channeled Scablands Journal Geol ogy Vol 33 pp 236259 1928 The Channeled Scabland of Eastern Washingtonquot Geographical R vit IU Vol 18 Pp 446477 1969 The Lake Missoula Floods and the Channeled Scablands Journal Geology Vol 77 pp 505543 Bretz J H H T U Smith and G E Neff 1956 Channeled Scabland of Washington New Data and Interpreta tions Geological Society America Bulletin Vol 67 pp 9571049 Condon Thomas 1871 The Willamette Soundquot Overland Monthly pp 468473 Dehlinger P R G Brown E F Chiburis and W H Westphal 1963 quotInvestigations of the Earthquake of November 5 1962 North of Portland Ore Bin Vol 25 pp 5368 Diller J S 1896 A Geological Reconnaissance in Northwestern Oregonquot US Geological Survey 17th Annual Report pp 441520 Fecht K R S P Reidel and A M Tallman 1985 quotPaleodrainage of the Colum bia River System on the Columbia Plateau of Washington State A sum mary Rockwell Hanford Operations RHO BWSA 318P prepared under US Department of Energy contract DE AC06 77RL01030 Richland Washington 55 pp Glenn J L 1965 Late Quaternary Selimenta tion and Geologic History of the North Wil lamette Valley Oregon Unpublished Doc toral Dissertation Oregon State Univer sity Corvallis 231 pp Sray J J G R Allen G S Mack 1978 quotRock Material Resources of Clackamas Columbia Multnomah and Washington Counties Oregonquot Oregon DJt Jtl llllt ill Geology and Mineral lndustries Special lr7J t39 3 54 0z I Griggs G B L P Kulm A C Waters G A Fowler 1970 quotDeepsea Gravel from Cascadia Channelquot Journal Geology 78611619 Ileinrichs D F and J Pietrafesa 1968 quotThe Portland Earthquake of January 27 1968quot Ore Bin Vol 30 pp 3740 Hodge E T 1938 quotGeology of the Lower Columbia River Geological Society America Bulletin Vol 49 No 4 pp 831 930 39 Iloffstetter W H 1984 quotGeology of the Portland Well Fieldquot Oregon Geology Vol 46 No 4 pp 6367 39 Hooper P R 1982 quotThe Columbia River Basaltsquot Science Vol 215 No 4539 pp 1463 1468 39 Ilotz P E 1953 Limonite Deposits near Scappoose Columbia County Oregonquot US Geological Survey Bulletin 982 C pp 7593 Lentz R T 1981 The Petrology and Stratigraphy of the Portland llillsquot Silt A Pacific Northwest Loess Oregon Geology Vol 43 No 1 pp 39 Lowry W D and E M Baldwin 1952 quotLate Cenozoic Geology of the Lower Columbia River Valley Oregon and Washington Geologic Society American Bulletin Vol 63 No 1 pp 1 24 Mullineaux D R R E Wilcox W F Ebaugh R Fryxell and M Rubin 1978 quotAge of the Last Major Scabland Flood of the Columbia Plateau in Eastern Washington Quaternary Research Vol 10 No 2 pp 171180 Pardee J T 1942 quotUnusual Currents in Glacial Lake Missoula Montanaquot Geological Society America Bulletin Vol 53 pp 15691600 Parsons R B 1981 Comment and Reply on quotThe Petrology and Stratigraphy of the Portland llills Silt A Pacific North west Loessquot Oregon Geology Vol 43 No 4 p 53 Parsons R B and G Green 1982 Geoinorphic Surfaces and Soil Developinent Multnoniali County Oregon US Department Ag riculture Soil Conservation Service West Technical Service Center Portland Ore gon 16 pp Reidel S P P E Long C W Myers and J Mase 1982 New Evidence for Grea 39 ter than 32 km of Columbia River Basalt Beneath the Central Columbia Plateauquot American Geophysical Union Transactions Vol 63 p 173 Schlicker H G I R Deacon and N H Twelker 1964 quotEarthquake Geology of the Portland Area Oregon Ore Bin Vol 26 pp 209230 Schlicker H G and R J Deacon 1967 Engineering Geology of the Tualatin Val ley Region Oregonquot Oregon Department Geology and Mineral Industries Bulletin 60 103 pp Schemla R J and L A Palmer 1972 quotGeologic Analysis of the Portland Hills Clackamas River Alignment Oregon Ore Bin Vol 34 pp 93103 Snaveley P D r N W MacLeod H C Wagner 1973 Miocene Tholeiitic Basalts of Coastal Oregon and Washington and Their Relations to Coeval Basalts of the Columbia Plateauquot Geological Society America Bulletin Vol 84 No 2 pp 378424 Stauffer J 1956 Late Pleistocene Flood Deposits in the Portland Area Geologic Newsletter Geological Society Oregon Coun try March pp 2131 Swanson D T L Wright P R Hooper and R D Bentley 1979 quotRevisions in Stratigraphic Nomenclature of the Colum bia River Basalt Groupquot l1S Geological Survey Bulletin 1457G 59 pp Theisen A A 1958 Distribution and Charac ter of lDC SSlll Soil in Nortlnvestem Oregon Unpublished master s thesis Soils Depart ment Oregon State University Corvallis 65 pp Theisen A A and E G Knox 1959 quotDis tribution and Characteristics of Loessial Soil Parent Material in Northwestern Oregon Proceedings Soil Science Society America Vol 23 No 5 pp 385388 Tolan T L and M H Beeson 1984 quotInter canyon Flows of the Columbia River Basalt Group in the Lower Columbia River Gorge and their Relationship to the Troutdale Formation Geological Society fgyerica Bulletin Vol 95 No 4 pp 463 Tolan T L M H Beeson B F Vogt 1984 quotExploring the Neogene History of the Columbia River Discussion rand Geologic Field39Trip Guide to the Colum bra River Gorge Oregon Geology Vol 46 No8 pp 8797 Portland s Landscape Setting 1939 Treasher R C 1942 quotGeologic History of the Portland Areaquot Oregon Department Geology and Mineral Industries Sliort Paper 7 Trimble D E 1963 quotGeology of Portland Oregon and Adjacent Areas llS Geolog ical Survey Bulletin 1119 119 pp Waitt R B 1980 quotAbout Forty LastGlacial Lake Missoula Jokulyhlaups through southern Washington Iournal Geology Vol 88 pp 653679 15 K 4 u nuau yr L quot 1 39 39I 1 39 39 39nIn39Fquotquotquot39 v Geologic and Physiographic Provinces of Oregon SCOTT F BURNS Dept of Geology Portland State University Introduction Oregon has an exciting geologic history that goes back to its oldest rocks which were formed almost 400 million years ago Through out the state one can find examples of most types of rocks minerals faults folds landforms and fossils Oregon is a geol ogist39s paradisequot for it has such a rich history Most geological processes are active here today The major geological hazards have examples in Oregon whether they are floods landslides earth quakes erosion or volcanic processes The next section of this paper discusses the highlights of Oregon s geologic history Each geographic province of the state is then described covering the characteristic rocks and minerals the development of the geologic units interesting landforms mineral resources and geological points of interest The different provinces are discussed in order of their ages from oldest to youngest Each of the nine provinces has developed in a different manner and has a unique geology Figure 39 Oregon39s Geologic History and Plate Tectonics Oregon39s geologic history began almost 400 million years ago Ma when this region was covered by warm seas and Nonh America39s western coastline was where Idaho is today Oregon has grown westward in its history as island land masses have been added to the continent called terranes or exotic terranes and volcanic eruptions have filled in the regions between the terranes Oregon has de veloped at an active convergent plate boundary PHYSIOGRAPHFC PROVINCES OF OREGON wAHNGT H oescuures uiumtu PLATEAU BLUE KIJNTAIHS PACIFIC ocean COAST RANGE IDAHO OWYHEE UPLAND 5 DE RANGE KLNIATH HOUNTAINS BASIHSRAHGE CAIJFORNIA Oregon is on the North American plate that started its westward journey approximately 200 Ma when the Atlantic Ocean began to open up This plate collided with the Farallon plate that was moving in an easterly direction Because the Farallon plate was mostly oceanic it subducted under the North American plate producing a chain of volcanoes to the north of today s Oregon in a line running n0rthwest southeast Between the trench and the chain of vol canoes was the forearc basin On the other side of the volcanoes was the backarc basin On the Farallon plate there were islands and other land masses that were not subducted but they were attached or accreted to North America as exotic terranes The old pieces of rocks formed the Blue Mountains and the Klamath Mountains In fact possibly up to 75 of the state has accreted terranes under the ground Orr et al I992 From 4432 Ma Oregon had its first signi cant volcanism Orr et al 1992 Vlfrth time the subduction trench the island arc of volcanoes and the forearc and backarc basins rotated west About 3025 Ma the trench and chain of volcanoes arrived at their current position At the same time the ridge of the Farallon plate was subducted Nonh America relaxed creating the basin and range region and the San Andreas Fault opened up From 30 to l7 Ma the Ancestral Cascades had continuous volcanic eruptions with sizes many times the size of the I980 Mt St Helens eniption About I7 Ma the Cascades volcanism subsided and the generation of flood basalts from noriheastem Oregon started Also at the same time other ood basalts were being produced in Oregon such as the Steens Mountain volcanic vent Gigantic calderas developed in the Owyhee Uplands As the flood basalts subsided about 12 Ma the Cascades became more active again Significant additions to the Western Cascades were formed in this time but the last million years was the time of development of the High Cascade cones we have today During this time much of Oregon was rotated in a clockwise direction Large subduction zone earthquakes have been part of the history of the Paci c Northwest for a long time Yeats 1989 Wong et al 1990 The remnants of the Farallon plate are called the Gorda Plate off the coast of California the Juan de Fuca plate off the coasts of Oregon and Washington and the Explorer plate off the coast of Vancouver Island The Juan de Fuca plate moves about as fast as your frngemail grows approximately one inch per year It is generated at a spreading center a couple of hundred miles off the coast The plate is subducted in the Cascadia trench off the Oregon coast The chain of volcanoes of the Cascade Range lies above the zone where the plate melts at depth Blue Mountain Province The Blue Mountain province is not a homogeneous chain of mountains but a cluster of smaller ranges Figure The topography rises going from west to east In the west there are the low hills of the Ochoco Aldrichand Strawberry Mountains In the middle there are the Elkhom and Greenhom Mountains The Wallowa Mountains in the northeast have nine glaciated peaks over 9000 ft in elevation l is 0 GEOLOGIC AND PHYSIOGRAPHIC Pnovrncrs or OREGON The oldest rocks in the state are found in this province which is a patchwork of Permian Triassic and Jurassic ancient island terranes that were accreted to Oregon s prehistoric shoreline in late Mesozoic time Silberling and Jones I984 These exotic terranes are exposed in linear strips that are layered on top of one another in a southwest to northeast trend There are ve major terranes in the Blue Mountain province Walker 1990 Vallier and Brooks 1986 Irwin l977 Each of the terranes is separated from the next by a major fault The Old Ferry terrane is exposed southeast of Baker City It is an ancient island archipelago of volcanic and sedimentary rocks Volcanic rocks are a combination of mainly pyroclastics ash and silicarich rhyolites with lesser amounts of basalt and andesite Marine sandstones siltstones and limestones form beds between the volcanic rocks Fossils from these sedimentary rocks have been dated from 220 Ma to I70 Ma Minimal folding is found in this Unll Exposures of the lzee terrane are found south of the town of John Day and directly west of the Old Ferry terrane This assemblage of layered rocks was formed in an ancient forearc basin between the island archipelago and the trench of a subduction zone The sequence of sedimentary rocks is twelve miles thick and is composed mainly of limestones mudstones and sandstones The sequence has been highly folded by compression and thrusting events and has been intruded by I00 Ma old granites The smallest terrane is the Grindstone terrane which isslocated southwest of the town of John Day andtwest of thelzee terrane in eastem Crook County The sedimentary rocks making up this terrane were formed in a shallow ocean backarc basin and are tenned a melange a highly contorted group of rocks formed when different geologic environments are telescoped together by colliding plates A 200feetthick unit of limestones cherts and argillites represents Oregon39s oldest rocks at 380 Ma On top of this Devonian unit is a 2500feetthick unit of Mississippian and Pennsylvanian aged limestones mudstones sandstones andcherts and a 900 feet thick formation of Permian limestones chens and sandstones The Baker terrane was formed as a deep ocean floor crust and extends from the west to the east north of the Olds Ferry Izee and Grindstone terranes The oldest rocks of this terrane are the 5000 feetthick Burnt River schist On top of it is another 5000ft thickness the Elkhom Ridge argillite Both sets of rocks represent metamorphosed deep oceanic muds and cherts Exposed just south of the town of John Day is the Canyon Mountain Complex which is an ophiolite zone that was fonned at a spreading ridge Rocks present are argillites cherts gabbro diorite volcanic tuffs pillow lava basalts and serpentine which has been formed through metamorphism The Baker terrane has been severely folded and faulted as it was squeezed into an accretionary wedge 220180 Ma North of the Baker terrane is the Wallowa terrane which was a volcartic archipelago environment formed 270180 Ma The five milethick sequence of rocks has mainly volcanic rocks at the bottom that have been covered by limestones and shales formed in shallow warm seas that covered the old volcanic chain Granites granodiorites and gabbros intruded 160 to 120 Ma into these formations and the heat and pressure metamorphosed some of the rocks into marbles and slates The Bald Mountain and Wallowa batholiths are the largest of these intrusions The Bald Mountain batholith extends over 144 square miles and the Wallowa batholith is Oregon39s largest at 324 square miles These intrusions helped cementquot the terrane together The terrane is heavily sheared by faults The Seven Devils Group of the terrane is thought to be the southernmost part of Wrangellia parts of an ancient continent that extended from the Wrangell Mountains of Alaska to Oregon Jones et al 1977 For the last 65 million years the Blue Mountain province has been above sea level About 44 Ma a chain of volcanoes developed in the western part of the province erupting andesitic and rhyolitic lavas Today the rocks and debris flows of these eruptions are called the Clarno Formation The Clamo volcanic episode was replaced by eruptions of the John Day period about 36 Ma to about 18 Ma at the western edge of the province Much of the ash and sediment from the eruptions was deposited in a basin centered where the town of John Day is today Excellent fossil preservation of the semitropical vegetation and mammals is found in the John Day Formation which with some sections of the Clarno Fomiation are now protected in the 14012 acres of the John Day Fossil Beds National Monument The rock exposures can be viewed at three locations Palisades at Clarno the Painted Hills north of Mitchell where one can view rust red soils Retallack 1991 altemating with the light brown tuffs of the John Day Formation and Picture Gorge 38 miles west of John Day where the gorge cuts through 1500 feet of basalt Ancient Indian pictographs have been found in the gorge leading to its name The northern part of this province was covered by the vast basalt flows of the Columbia River basalts from 17 Ma to about 12 Ma At the same time three andesitic volcanic centers were also erupting in a straight line running northeastsouthwest through the province They produced Sawtooth volcano Strawbeny volcano and Dry Mountain volcano The Strawberry volcanics alone cover a total of 1500 square miles and are over a mile thick at Ironside Mountain in Malheur County Pleistocene glaciation affected all of the ranges in the province except the Ochoco Mountains The Wallowa Mountains show the greatest glacial erosion with abundant homs tams cinques and u shaped valleys present The most beautiful peak in the range may be the white marble Matterhom Mountain which rises to l0004 feet in elevation The peaks and valleys were carved by nine major glaciers with the Lostine Minam and rrtnaha glaciers all over 20 miles long Spectacular terminal moraines form a natural dam for Wallowa Lake Today the glaciers have melted leaving only snow elds in the cirques During the last 65 million years the Blue Mountain province has rotated 65 degrees clockwise as a result of a dextzral shear between 57 l J l jg GEOLOGIC AND Prrvsrocruuvnrc PROVINCES OF OREGON crustal blocks to the north moving south and blocks to the south moving north Walker I990 A major anticline extends south west northeast through the heart of the province It runs parallel to the Ilamath Blue Mountain lineament and may represent a deeply buried suture between two microplates in the crust below The province is also the end of another lineament that extends to the northwest across the Columbia plateau and is called the Olym pic Wallowa lineament Three fourths of the gold mined in Oregon has come from this province Brooks and Ramp I968 Gold was fast reported in 1845 but the true gold rush started in 1861 Lode gold and placer gold were mined mainly in a strip 50 miles wide and 100 miles long between John Day and the Idaho border Gold originated mainly along the edges of the Cretaceous and Jurassic batholiths Extensive silver copper and mercury rrtining also was lucrative Copper was found mainly in hydrothennal deposits in sheared fault zones of the oldest volcanic and sedimentary rocks Mercury was obtained from cinnabar taken from the Clamo Fomiation where it was associated with faulted intrusive volcanic plugs Thundereggs Oregon39s official state rock are found mainly in the rhyolite and tufif deposits at the western edge of the province especially the John Day Formation These agate and opal deposits have lled gasproduced cavities in the highly viscous magmas Ilell s Canyon of the Snake River is North America s deepest canyon and is located on the Oregon boundary with Idaho at the eastern edge of the Wallowa Mountains It is nearly 8000 feet deep and is 1000 feet deeper than the Grand Canyon Orr et all992 Over I75 milllion years of geologic history are exposed in the can yon walls Officer s Cave which is 11 miles south of Kimberly in Grant County is one of the largest nonlimestone caves in North America Underground streams have eroded the clays and silts of the John Day Formation to fomi this cave which over 1500 feet long Klamath Mountain Province The Klamath Mountains make up a north south trending province of 12000 square miles 60 of it lies in Califomia Orr et al 1992 Figure For the most part the province exhibits an even relief typical of an old land surface It is characterized by deep canyons that have been incised into this surface since it was last uplifted The Siskiyou Mountains on the southem edge of the province show the greatest relief and Mt Ashland is the highest peak at 7530 ft elevation The province is mainly drained by the Rogue River which starts in the Cascades and traverses 215 miles to the Paci c Ocean Like the Blue Mountain province the Klamath Mountains are also exotic terranes that were once part of the ocean flood or an island archipelago that has bexan accreted onto North America Seven terranes are found in the Oregon Klamath Mountains Gray 1986 Pessagno and Blome 1990 Two older terranes are located in the California portion of the province and date back 450 Ma These terranes have been welded together by granitic intrusives about l40155 Ma and have been rotated by the dextral shear mentioned in the Blue Mountain section about 100 degrees clockwise Because of the similarity with the Blue Mountain terrane related to rotation it has been suggested that the two terranes are connected beneath the Cascades Uplift of the terranes started about 20 Ma The oldest terrane is at the eastern end of the province and the terranes get younger to the west Each terrane is separated by a major fault More than 250 Ma the Klamaths were part of an archipelago that extended from presentday British Columbia to Califomia They were accreted onto the continent about l75 l40 Ma The northem portion of the archipelago became the Cache Creek area of central British Columbia the central portion became the Blue and Klamath Mountains of Oregon and the southem portion became a part of the Sierra Nevada Mountains of eastem Califomia These rocks all have similar fossils Many of the terranes in the Klamaths contain oceanbottom rock sequences called ophiolites Ophiolites are a sequence of rocks formed on the deep ocean lloor next to a spreading center They may be up to three miles in thickness and have a sequence of rocks from bottom to top of ultramalic peridotite gabbro pillow basalts and a capping of deep sea cherts and pelagic clays Many times the porous pillow basalts have sul de mineral deposits formed from seawater convection at the spreading centers These pillow basalts can be mineralized with copper lead zinc and smaller amounts of gold silver and platinum Nickel and chromium are generally associated with the lower peridotite layer Many of the Klamath ophiolites have been changed to lowgrade metamorphic rocks such asgreenstone and serpentine The Westem Paleozoic and Triassic sometimes called the Apple gate terrane is the oldest and most easterly terrane in the Klamath province It is subdivided into three subterranes the Rattlesnake Creek subterranewhich is an ophiolite the Hayfork subterrane which is a volcanic island archipelago and the May Creek ophio lite which has been highly metamorphosed The Westem Klamath terrane is found toquot the west of the Applegate and has been divided into six subterranes The Condrey Mountain subterrane was oceanic bottom that was metamorphosed to schist 146 to I48 Ma The Smith River subterrane has great mineral wealth which comes mainly from the Josephine ophiolite which was formed 163 Ma at a tropical latitude spreading center It is one of the most complete ophiolite sequences in the world and its massive sul de deposits resemble those of the island of Cyprus Orr et al 1992 The threemile thick Galice Fonnation overlies the Josephine ophiolite and contains turbidites of sandstones which grade into shales The Condrey Mountain schist probably came from sediments similar to the Galice Fomiation The Rogue Valley subterrane is mainly volcanics that have been metamorphosed to greenstones that locally contain gold and other base metals The Briggs Creek subterrane to the west consists of folded and altered gamet bearing amphibolites The Dry Butte subterrane consists of mainly Illinois gabbro which may have been the roots of the volcanic arc The Elk subterrane contains the Galice Fonnation and coarse marine gravels that have formed conglomerates W I quot GEOLOGIC AND PHYSIOGRAPHIC PROVINCES OF OREGON The other five younger terranes are found at the west end of the Klamath Mountains province The Snow Camp terrane consists of the Coast Range ophiolite and the Riddle and Days Creek formations of conglomerates siltstones and sandstones The Pickett Peak terrane is mainly made of the highly metamorphosed Colebrooke Schist Formation which may have been an ophiolite The Yolla Bolly terrane consists of the Dothan Formation of oceanic continental slope rocks of turbidite sands and muds with some deepwater cherts The Gold Beach terrane is a melange of siltstones sandstones breccias cherts that are extensively mixed with schists and lavas The Sixes terrane which is exposed just north of Cape Blanco on the coast and also inland south of Roseburg is a mixture of mudstones sandstones conglomerates blueschists eclogites limestone and shales The terranes were all cemented together during a period of intense folding and faulting from 140 to I55 Ma when four main plutons formed in northeast trending belts Hotz I971 The Wooley Creek belt formed at I55 Ma of quartz monzonite and granodiorite The Greyback belt and the Chetco belt of gabbro both intruded at I53 Ma The Grants Pass plutonic belt was the last one to intrude at 140 Ma Mineralization at the edges of the plutons was important for concentrating economic minerals Minor glaciation did occur at elevations of 40006000 feet especially around Chetco Peak near the California border Minimal development of marine terraces occurred along the coast because of the resistant rocks and constant landslidingwherexthere is abundant serpentine or the rocks are crushed in thrusts or are melanges The coastline southof Cape Blanco does not resemble the coast further north because the resistant rocks have eroded into mainly headlands and offshore stacks and shoals Hunter et al 1970 These many stacks and shoals were once connected to the mainland but are now erosional remnants Goat Island is the largest coastal island with an area of 21 acres The area of stacks from Gold Beach to Cape Blanco is part of an extensive reef complex The Klamath Mountains have a rich history of mineral exploration Brooks and Ramp I968 The ophiolite sequences have long been exploited for their iron and copper sul de deposits Pillow basalts formed around hydrothermal vents on the bottoms of the oceans concentrated copper gold silver cobalt and zinc Probably the most exploited unit was the Josephine ophiolite in the Westem Klamath terrane The lower parts of the ophiolites the peridotite zone are an excellent source of nickel and chrome Both have been mined in the Klamaths The last operating nickel mine in the United States closed in 1987 near Riddle Both of these are mined out of the ophiolites that have been highly weathered and formed lateritic soils The nickel is not weathered so is easily separated from the rest of the soil Major gold and silver deposits have been associated with the edges of the plutons especially the Chetco complex and the Ashland pluton Gold was discovered in 1850 on the Illinois River and the gold rush began in 1851 and centered around Jacksonville which at that time was at the center of the most populated county in Oregon Most of the early mining was placer lode mining began in the 186039s Over 75 ofthe gold mined in the Klamaths came from placer mining The Oregon Caves National Monument is located 20 miles southeast of Cave Junction and was formed in the marble portions of the 190 Ma Applegate Formation Walsh and Halliday 1976 It is really only one cave which is about 03 miles long It was discovered in 1874 by Elijah Davidson and contains classic deposits of calcite stalactites and stalagmites Basin and Range Province The Basin and Range province is located in the south central part of the state Figure It is the northem part of the Basin and Range province of the United States that extends from Utah to California and Idaho to Arizona encompassing over 300000 square miles or 8 of the United States Orr et al 1992 It is a series of nonh southtrending narrow faultblock mountain ranges alternating with broad basins It extends from the Klamath Lake basin in the west to the Alvord basin in the east Most of the province is over 4000 feet in elevation with the crest of the Steens Mountain the highest point at 9670 feet One of the fault block mountains Hart Mountain is considered to be the best de ned faultblock mountain in the United States at 7710 feet elevation Orr et al 1992 Many of the basins are closed and only the Klamath River reaches the sea Extensional tectonics have dominated the geologic evolution of this province Eaton 1984 From about 20 to 10 Ma the first phase of extension gave rise to the Nevada Oregon rift the western Snake River graben and eastem Oregon fractures that in tum gave rise to volcanic dike swarms that produced the Columbia River and Steens Mountain basalts The second sequence of extensional tectonics of the last ten million years produced the characteristic faultblock mountains and the horstandgraben topography It has been estimated that the crust has been stretched to the point that this province has expanded 100 in this time period Wells and Heller 1988 Normal faults form the edges of these five major horsts tilted upliftgd mountains and the five main grabens the down dropped basins At the same time there has been a clockwise shift in the stretching direction from northeastsouthwest to north westsoutheast Wells and IIeller 1988 Faults that have northwest trends show relatively small displacements on the order of 150 feet maximum whereas faults with a nonheast trend show displacements up to several thousands of feet Accompanying the stretching of the crust has been a thinning of it which has brought hot crustal rocks into contact with the water table Many thermal springs and explosion craters and maars are situated above faults There is high heat flow in this province Bowen et al 1978 IIot springs have been noted along faults in the Alvord Desert near Lalceview and in the Warner Valley These areas have been investigated for geothermal energy potential In the Alvord basin Mickey IIot Springs discharges boiling water and the Alvord IIot Springs have an average temperature of 169 degrees F and a How rate of 132 gallons per minute Geyser eruptions have been noted at Hunters Hot Spring near Lakeview and me Cnimp Geyser in Warner Valley GEOLOGIC AND PlIYSIOGRAPHIC Paovmcrs OF OREGON Volcanic rocks basalts and tuffs are the main rocks exposed in the province Rytuba 1989 They are over 10000 feet thick and have completely covered the basement rocks Across the border in Califomia Paleozoic and Triassic metamorphic rocks including phyllites and greenstones and granitic intrusions are exposed below the volcanic rocks These older rocks suggest that the Basin and Range province overlies an older accreted terrane than those of the Klamath and Blue Mountains Most of the volcanic rocks in the province have formed in the past 20 million years Rytuba 1989 The initial extension about 16 million years ago produced the most extensive volcanic event in the province andesitic basalt lava developing from a shield volcano centered near Steens Mountain Its flows averaged 3000 feet thick and covered 6000 square miles for a total volume of over 3000 cubic miles Orr et al 1992 Although the volume was only 10 of the Columbia River basalts this large amount of lava was erupted over a duration of only 50000 years Rhyolitic lavas were also extruded across the province in the last ten million years The rocks get progressively younger going from southeast to northwest from 10 Ma to 1 Ma Two volcanoes erupted in the middle of the province and showed different eruptive histories Gearhart Volcano began about I 1 Ma with basalt and ended with a veneer of andesite Yamsay Volcano which is north of it erupted 4 Ma and has a bimodal history of starting as a shield cone of basalt and ending with rhyolitic lavas Increased precipitation and runoff from glaciers on Steens Mountain during thePleistocene era fedquot1arge39pluvial lakes that occupied the basins of the province One can still see evidence of these large lakes today Ancient elevated beaches waterlinesand gravel deltas are found at the edgesof the basins today Lake Modoc was the largest of the nine large pluvial lakes It had an area of 1096 square miles and occupied the basin where Upper and Lower Klamath Lakes are today Dicken 1980 In the central portion of the province was Lake Chewaucan It was 375 feet deep at the center and had a surface area of 461 square miles Allison 1982 Warner Lake was the large lake in Lake County with an area of 483 square miles and Alvord Lake in Harney County had a surface area of 491 square miles These lakes began to dry up about 1 1000 years ago Steens Mountain was glaciated during the Pleistocene era The best glacial featttres are found on the west side of the mountain only small glaciers occupied the eastem side Little Blitzen Canyon and Kiger Gorge are excellent examples of ushaped valleys Antimony lithium copper and gold have all been reported in the province but only uranium has been mined successfully The uranium is found mainly in rhyolitic rocks and lake sediments as uraninite and cof nite Owyhee Uplands Province The Owyhee Uplands are found in the southeast portion of the state Figure It is essentially a large horst at the eastem end of the Basin and Range province in Oregon This region is a at deeply dissected plateau that is mainly drained by the Owyhee River The river has deep canyons and a welldefined drainage pattem in spite of the low rainfall in that portion of the state The river and its tributaries have steep gradients widi the Owyhee starting at over 6000 feet in elevation and dropping to approximately 2000 feet elevation where it joins the Snake River The Owyhee Uplands are a complex series of overlapping volcanic calderas of very large size that erupted during the Miocene era Kittleman 1973 Extensive ashflow tuffs were produced by these eruptions The oldest and largest caldera is the McDermitt complex which straddles the Oregon Nevada Line at the south end of the province The diameter of the caldera is 22 miles and it erupted 161 to 156 Ma Six other calderas make up the McDerrnitt field which is located to the southeast of Steens Mountain Rytuba and McKee 1984 The Lake Owyhee Volcanic Field is at the northem end of the province Four major calderas make up the field Rhyolitic magma that erupted as tuffs and ash are characteristic of the volcanic eruptions that produced these calderas Mahogany Mountain and Three Fingers Caldera both erupted about 155 Ma producing circular depressions of ten and eight miles in diameter respectively Saddle Butte caldera to the south is about 15 miles in diameter and the Castle Peak caldera at the northern end is over 20 miles across To give one a feeling of the size of these immense calderas Crater Lake and Newben39y Calderas are six and five miles in diameter respectively Many of the ash ow deposits of the province have been reworked by streams Some of the longest I lava caves in the state are formed in the Saddle Butte tuff cones near Burns Junction Caves have been traced over eight miles in length The Owyhee Basalts erupted onto the plateau from about 13 to 12 Ma and covered a good portion of the ashflow tuffs In Owyhee Canyon the maximum thickness noted in these basalts is 1500 feet One of the last eruptions in the province produced the Jordan Craters Natural Resource area which is 36 miles southwest of Adrian This 28squaremile area of basalt erupted over the period of 9000 to 4000 years before the present The landscape has many spatter cones pahoehoe lava flows lava tubes and the main crater Coffeepot Crater Otto and Hutchinson 1977 Just south of this area are three small shield volcanoes of basalt of the same age Clarkes Butte Rocky Butte and Three Mile Hill The richest supply of mercury in the Western Hemisphere has been taken from the Opalite Mining district found within the McDerrnitt caldera complex A total output of 270000 asks of mercury have been extracted since 1917 Uranium has also been mined in the McDermitt complex Possible heap leach mining has been proposed for deposits in the Grassy Mountain area of the province but strict environmental regulations will probably prohibit its development Diatornite has been successfully mined in the Juntura and Otis basins for use as kitty litter and ltering powder The Sucker Creek fomiation along the Idaho border has also been mined for bentonite weathered volcanic ash to be used as a drilling mud and also a sealant for dams and ponds and for zeolites for water softeners l GEOLOGIC AND PHYSIOGRAPHIC PROVINCE3 OF OREGON Two very beautiful vertical pinnacles have been formed by the erosion of the volcanic sediments of this province Four miles south of the town of Rome in Malheur County are high vertical pillars that resemble Roman ruins where Jordan Creek enters the Owyhee River They are pan of a badland topography produced by erosion of a 400feetthick section of Pliocene tuffaceous sediments that had lled the Owyhee Valley earlier during an alluvial period Similar columns are exposed in Leslie Gulch approximately 23 miles south of the Owyhee Dam The columns have brown cream and white colors that developed in the streamdeposited ash flow tuffs that were produced from the eruption of Mahogany Mountain 155 Ma High Lava Plains Province The High Lava Plains province lies approximately at the geographic center of the state Figure It is considered highquot because the average elevation is over a mile and the elevation ranges from a low in the Harney Basin at the east end at 4080 feet to the high of 7984 feet at Paulina Peak at the west end of the province The province forms a rectangle that is approximately 50 miles wide and 150 miles long Because the precipitation is less than 20 inches per year there is only a poorly developed stream drainage system and there has been very little erosion of volcanic and tectonic feantres The one hundred eruptive centers of the province are all aligned along the Brothers Fault Zone Walker and Nolf 1981 which extends 130 miles from Steens Mountain to Bend It is a zone of many parallel faults that have been formed by the same forces that have twisted Oregon in a clockwise motion in the Cenozoic era Dextral shear between the earth39s crust to the southwest of the fault zone that is moving north and the crust to the northeast of the fault zone that is moving south has formed these many wrenchquot faults The volcanic eruptions along the 100 centers have been bimodal Walker and Nolf 1981 At first they are basaltic because the source is deeper in the crust and therefore hotter magma comes to the surface The last phases of the eruptive cycle produce rhyolite in the form of pumice ash and thick lava flows This rare type of volcanism is found where the crust is thinning and is under tension The volcanoes range in size from small cinder cones tuff rings and explosion craters to the largest shield volcano in the state Newberry Crater The ages of the rocks decrease geographically from east to west Walker and Nolf 1981 In the Hamey Basin the last eruption was Duck Butte at 96 Ma Going west the ages get younger Squaw Butte 57 Ma Glass Butte 49 Ma Quartz Mountain ll Ma and China Hat 8 Ma Newberry Crater at the west end had an eruption only 1600 years ago A possible reason for the movement of the eruptive front westward is the steepening of the subduction zone because the Farallon plate has slowed down its subduction rate In order to maintain a 90mile distance between the melting rocks of the subducting plate and the erupting volcano at the surface the eruptive center would shift west as the subduction zone steepens to the west The eastem end of the province is theHarney Basin which is a downwarped closed basin Walker I979 It is 5300 square miles and it was downwarped after extensive evacuation of magma chambers of caldera eruptions about ten million years ago Hot springs are common in the basin along faults Radium Hot Springs has been a popularsite with the public for over a hundred years Newbeny Crater lies at the westem end of the province at the convergence of three major fault zones the Brothers Fault from the southeast Sisters fault from the north and the Walker Rim fault from the southwest Chitwood and McKee 1981 It became a National Monument in 1991 At 40 miles long and 20 miles wide and covering over 500 square miles it is one of the largest Quaternary volcanoes in the United States Orr et al 1992 Over 400 cinder cones are found on its anks Lava Butte just south of Bend is an example that lies at the edge of a basalt flow formed 6000 years ago on the northwest flanks of Newbeny Crater The flows diverted the Deschutes River to the west In that flow are many lava caves with the Lava River Cave being one of the longest uncollapsed lava tubes in Oregon Newberry Crater is about half a million years old Most of its earlier eruptions were basalt flows but more recently rhyolitic magma has been discharging The Big Obsidian flow in the crater erupted just 1600 years ago Another major obsidian volcanic center is Glass Buttes which is east of Newberry Crater It was fonned ve million years ago ln addition to black obsidian it also has produced mixtures of red and black obsidian Just as in the Basin and Range Province five major pluvial lakes were present in the Pleistocene era The largest one occupied Fort Rock Valley and had a surface area of 1400 square miles Three nearby lakes occupied Christmas Lake Valley Silver Lake and Fossil Lake They were all interconnected and had an average depth of 200 feet At the other end of the province Malheur Lake had a surface area of 900 square miles Explosive eruptions of maars and tuff rings were distributed across the High Lava Plains Peterson and Groh 1964 When upward moving lava intercepts groundwater an explosion occurs Rocks and ash are thrown into the air and then settle close to the crater building up a steep tuff ring or high rim Shallow explosion craters are called maars and are saucer shaped They usually fill with angular pieces of breccia Three concentrations of these explosive eruption landforms are located in northem and southem Lake County and southem Klamath County The most famous tuff ring is Fort Rock in Lake County Allison 1979 It is about a third of a mile across and about 325 feet above the surrounding plains The southern rim has been eroded by a pluvial lake s wave action Just north of Fort Rock is HoleintheGround which is a maar that is a mile in diameter The crater floor is over 300 feet below the surrounding plain To the northeast is Big Hole which is another maar about a mile across Extensive lava fields of cinder cones pahoehoe lava lava tubes domes and pumice are present in nonhem Lake County The Four Craters Lava field is on the northern edge of the Christmas Lake Valley 12 square miles The Squaw Ridge cone covers 200 square IE 4 GEOLOGIC AND PHYSIOGRAPHIC PROVINCES or OREGON miles and Devils Garden offers over 45 square miles of rough black lava flows spatter cones and lava tubes Diamond Craters in Hamey County is a very interesting volcanic site This 22 square mi1e area south of Malheur Lake has over 100 cinder cones with 30 of them located inside a ninemillionyear old caldera which is 3500 feet wide and has collapsed 200 feet The small cinder cones formed only 2500 years ago Peterson and Groh 1964 CrackintheGround is a narrow northwest southeast rift that is located in Lake County between Christmas Lake and Four Craters lava eld Peterson and Groh 1964 It is a crack in the Green Mountain basalt that is a few feet wide two miles long and up to 70 feet deep It is the surface expression of a normal fault formed when a graben formed in the basalt Smith Rock is a monolith north of Bend in the northwest portion of the province that is loved by rock climbers It is part of a volcanic center that enipted 1018 Ma Bishop 1989 Rhyolitic lavas and tan red and green tuffs of volcanic ash and mudflows form this rock Its steep cliffs have been fonned through erosion over the years by the Crooked River DeschutesUmatilla Plateau Province The Deschutes Urnatil1a province is located in the northcentral part of the state Figure It is the southem extension of the Columbia Plateau that covers over 63000 square miles of Washington Oregon and Idaho The province slopes to the nonh starting at elevations around 3000 feet in the south and the west and descending to elevations close to a couple of hundred feet at the Columbia River The Deschutes John Day and Umatilla Rivers are the main streams that drain the province Miocene production of basalt dominates the geology of this province Beeson et al 1989 The geology is mainly basalt flow on top of basalt flow from the Columbia River Basalt Group CRBG The Columbia Plateau is the secondlargest basalt province on land in the world second only to the Deccan Plateau of India The sources for the magmas were mainly fissures in northeast Oregon southeast Washington and western Idaho The magma owed generally westward into a subsiding basin Flows moved at velocities up to 30 miles per hour The total volume of the Columbia Plateau was about 42000 cubic miles with the greatest thickness being over three miles It may have taken decades for the flows to cool Little is known about the basement rocks under the basalts but they are probably extensions of the Blue Mountain terranes in the east and the Clamo and John Day Fomiations in the west The Columbia River Basalt Group was formed from 17 to 6 Ma Beeson et al 1989 The oldest flows were the Irnnaha basalts From 165 to 156 Ma the Grande Ronde basalts erupted Reidel et al 1989 They make up 85 by volume of the CRBG A total of 120 flows were produced giving a frequency of one How per every 10000 years Many reached the Pacific Ocean The Wanapum basalts were produced from 154 to 145 Ma The 36 flows of GEOLOGIC AND P1IYSIOGRAPHIC PRovtNcEs OF OREGON Wanapum averaged a flow every 20000 years The youngest flows of the Saddle Mountain basalt stretched out over a period of 135 to 6 Ma and the 19 flows averaged about one flow per every 400000 years Small basins developed on top of the basalt and collected sediments In the east in the Dalles Tygh Valley Basin over 1500 feet of volcanic sediments from the Cascades collected to form the Dalles Fomiation from 11 to 8 Ma Two similar formations formed in the Deschutes Basin which was closer to the Cascades The fine grained Simtustus Formation formed over a 250 foot thickness between 16 and 12 Ma from waterlaid tuffs sandstones and mud stones from the Cascades The Deschutes formation was much coarser and formed between 1000 and 2000 footthick volcanic sediments from 8 to 4 Ma Smith 1987 In the John Day Basin to the east volcanic sediments from the Cascades also collected from 8 to 5 Ma and formed the Rattlesnake Fomiation with a thickness between 500 and 700 feet In the Pliocene era between 4 and 2 Ma small volcanic cones developed in the upper Deschutes and Crooked River watersheds Shield volcanoes and cinder cones were built up at Squaw Back Ridge Tetherow Butte Round Butte Black Butte and Little Squaw Back At the end of the Pleistocene era the northem portion of the province was covered by the Missoula Floods from 15300 to 12700 years before the present Waitt 1985 The tectonic phases of development of the plateau can be divided into two important parts Catchings and Mooney 1988 From 17 to 10 Ma tensional stresses from apparent backarc spreading on the North American plate produced extensive north south fractttres that resulted in the CRBG flow production It also tilted the plateau to the west allowing the Grande Ronde flows to extend northward and enabled them to reach the coast via the Columbia Gorge Between 10 and 4 Ma the Pacific plate rotated 25 degrees clockwise to a more southwest by northeast direction This intense compression created east west wrinkles in south central Washington like the Yakima Fold Bell the Horse Heaven Hills and the Columbia Hills anticline The only mineral resource that has been mined in this province has been diatomite in the 195039s east of Terrebonne The 67footthick deposit was exhausted About the only geothermal resource is the resort operated at Warm Springs in the westem portion of the province Natural waters flow to the surface from a fault in the Clarno fomtation at 140 degrees F Cascade Mountains Province The Cascade Mountains province is probably the most beautiful in the state because of its majestic volcanoes Figure It extends from Washington to California and divides the state into the east and west portions The older deeply eroded Westem Cascades make up the westem portion of the province The younger snowcovered High Cascades sit on the eastem edge of the older Westem Cascades The Westem Cascades range in elevation from 1700 feet at the westem edge to 5800 feet on the eastern margin Peaks in the High Cascades reach over 11000 feet in elevation Precipitation 1 I A n K v39 39 1 ranges between 60 and l00 inches per year on the westem side resulting in deep weathering Cascade volcanism started up about 42 Ma as the Eocene shoreline was just to the west where the Willamette Valley is today Extensive volcanism was common before 20 Ma as the subduction rate of the Farallon plate was six times the rate today Hammond 1979 Duncan and Kulm 1989 By 25 Ma the Cascades had rotated into their present position Cascade volcanism subdued for a few million years as the flood basalts dominated the volcanic environment of Oregon Violent eruptions again started 13 Ma and continued until 9 Ma forming the Sardine Formation About 5 Ma the Western Cascades tilted west and were uplifted producing a rain shadow in eastern Oregon The subduction rate had slowed from 3quotyr to 5quotyr because the convergence angle was more oblique resulting in less volcanic activity About live million years ago the volcanism shifted to the formation of the High Cascades Priest 1990 First extensive basaltic volcanism developed from overlapping shield volcanoes of the High Cascades The eruptions were so extensive that large grabens formed as the magma chambers were empty and the volcanoes were collapsing into them These grabens were generally 10 to 20 miles wide and 30 miles long Finally in the Quaternary the andesitic cones developed in the graben to heights over l0000 feet in elevation Over 85 of the rocks produced in the High Cascades over the past ve million years are basalt Orr et al 1992 Glaeiation has changed the composite volcanoesthat quotmake upquot the High Cascades McBirney 1978 Mt Jefferson Washington ThreeFingered Jack Thielsen McLoughlin Broken Top and the North Sister are thin sharp remnants of older composite cones Only Mt Hood Bachelor and South Sister have retained their original composite volcano shape Today there are stillactive glaciers in the High Cascades Mt Hood has nine glaciers The Sisters have five with the Collier Glacier being the largest as it descends from the north slope of the Middle Sister Mt Thielsen has the most southerly Cascade glacier on its north side There have been recent eruptions in the High Cascades of Oregon Taylor 1990 There have been a number of eruptions from vents near Mt Bachelor from 2000 to 18000 years before the present The last eruption on Mt Hood was just before Lewis and Clark came down the Columbia River making it less than 200 years ago Between the North Sister and Three Fingered Jack are the youngest volcanic fields in the Cascades The Sand Mountain and Belknap lava elds have covered over 40 square miles with 22 basalt cinder cones and basalt lava flows from 41 separate vents The eruptions started about 4000 years ago and the last one came from Collier cone around 400 years ago There are five mining regions found in this province and they are in the Westem Cascades in a thirtymile strip west of and parallel to the highest peaks of the High Cascades Fems and Huber 1984 Gold and silver have been the main minerals extracted but small amounts of lead galena zinc sphalerite and copper chalce pyrite have been found The mining districts include the north 10 Santiam district of Marion County the Quartzville and Blue River districts of Linn County and the Fall Creek and Bohemia districts of Lane County The last district has been the largest and most productive Ten major hot springs are located along a twelvemilewide zone at the boundary between the High and Western Cascades Bowen et al 1978 The central portion of the Cascades has springs at higher temperatures and the springs are right on the boundary Bagby Hot Springs Belknap Springs Foley Hot Springs McCredie Springs Breitenbush Hot Springs and Kitson Hot Springs Umpqua Hot Springs Wall Creek Warm Springs Terwilliger Hot Springs and Austin Hot Springs are all located on the backbone of the Oregon Cascades Swim Warm and Kahneeta Hot Springs in the nonh and Jackson and Olene Gap Hot Springs in the south are located far from the boundary Temperatures of the spring waters range from 90 to I90 degrees F The greatest potential for geothermal explora tion is east of this boundary in the High Cascades Crater Lake became a National Park in 1902 to preserve this beautiful area About 7000 years ago Mt Mazama violently erupted abundant rhyodacitic pumice and pyroclastics Bacon I983 About six cubic miles of magma drained the underground chamber so the mountain fell into the magma chamber creating the large caldera that has become lled with water The volcano began its life about 400000 years ago and went through stages of andesite and dacite composite cones and basaltic shield cones Mt Mazama was estimated to have been between ten and twelve thousand feet in elevation and today the crater rim averages about 8000 feet elevation Vlfrzard Island is a small cinder cone that developed about a thousand years after the eruption in the caldera Today Crater Lake has a depth of 1932 feet and is the deepest freshwater body of water in the United States It is also the clearest lake in the United States because of lack of algal growth Hydrothemtal vents have been found at the bottom of the lake Coast Range Erovince The Coast Range province is over 200 miles long and between 30 and 60 miles wide and extends nonh from the Klamath Mountains to Washington along the west coast of the state Figure The average height of the crest of the mountains is about 1500 feet elevation and Mary s Peak near Philomath is the highest mountain at 4097 feet elevation The westem slopes of the range receive over 100 inches of precipitation each year whereas the eastem slopes receive only about 30 inches per year Active erosion of the westem slopes is common The coastline is characterized by headlands and bays estuaries and inland dunes Marine terraces also extend from Cape Blanco at the southern tip to Cannon Beach in the north The province also continues offshore to where the continental shelf and slope descend to the abyssal plain 9000 feet below sea level At the beginning of the Cenozoic about 66 Ma this whole region was under the sea The shoreline of North America passed through eastem Washington and down through Idaho A chain of seamounts was being generated at a hot spot that was sitting on the spreading center between the Kula plate that was heading nonh and the Farallon Juan de Fuca plate which was heading in an east l til GEOLOGIC AND PHYSIOGRAPHIC PROVINCES OF OREGON direcuon Some of these seamounts extended above the water and were undergoing subaenal weathering These seamounts collided with the North American plate and were submersed but not subducted Duncan 1982 They became the basement for a newly developing forearc basin as the new volcanic arc of the ancestral Cascades was moving into place close to its present position These basalts became the Roseburg Siletz and Ttllamook volcanics and have ages ranging from 62 Ma to 53 Ma from south to north North America expanded west by about 50 miles with the addition of these seamounts Snaevey et al I980 Snavely and Wells 1991 This new marine forearc basin received abundant sediment from the erosion of the newly developed Klamath Mountains the new volcanic arc of the ancestral Cascades and the Idaho batholith as the ancestral Columbia River developed in the Eocene Chan and Don 1983 In the southern part of the basin from about 55 to 40 Ma sands silts and clays eroded from the Klarnaths were deposited to eventually become the marine sedimentary rocks of the Roseburg bookingglass and Floumoy Formations The T yee Formation then developed but received more sediment from the north and the Idaho batholith in the formation of its marine sedimentary rocks Baldwin 1974 On a large delta in the Coos Bay region subtropical plants eventually became coal of the Coaledo Formation In the central portion of the forearc basin and northem parts of the basin sands muds and volcanic debris were deposited in shallow seas nearshore environments and brackish backwater bays The Yamhill Nestucca and Spencer Formations were the main units formed from these sediments At the northem end of the basin in similar depositional environments the sedimentary Cowlitz Keasey Pittsburg Bluff and Scappoose Formationsrwere 39 formed Between 38 and 29 Ma a number of intrusive bodies invaded the softer marine sediments Subsequent erosion of the sediments has exposed some of these as peaks in the range like Marys Peak west of Philomath which is capped by a 1000 feet thick flatlying sill of gabbro that was formed about 30 Ma Uplift of the Coast Range began 50 Ma and continued to about 20 Ma when most of it had been uplifted except the northem end and the Vlfillamette Valley Marine sediments were deposited at the northem end up until about l2 Ma when it became the Astoria Formation During that time the Columbia River basalts invaded the area coming down the Columbia River Beeson et al I979 Many flows reached the ocean and after erosion of the soft sediments around them have become the major headlands of the northem Oregon Coast Saddle Mountain west of Seaside is a mountain composed of Columbia River basalt that was a cooled intracanyon flow Some of the CRBG flows sank into the sediments and after cooling have become dikes and sills Marine tenaces are found along the coast from Cannon Beach south to Cape Blanco At the northern end of the coast there is mainly one terrace the Whisky Run terrace which is dated at approximately 80000 years BP The number of terraces increases from Newport to the south with five major terraces at Cape Blanco dating from 8000 to gt230000 years old Mclnelly and Kelsey 1990 Reilinger and Adams 1982 calculated that the uplift rates are 1 inch every 3 years at Cape Blanco and only 1 inch every 36 GEOLOGIC AND PHYSIOGRAPHIC PRovntcEs OF OREGON years at Astoria because Cape Blanco is much closer to the subduction zone The differing rates might account for the differing numbers of terraces on the coast Sand is important along the coast There are twelve major sand spits along the coast where rivers empty into the ocean Seven face south and five face north showing that there is no dominant direction of longshore drift along the coast In 907 a large resort opened on the Tillamook Spit and was called Bayocean It was advertised as the Queen of the Oregon Resorts An olympicsized natatorium was built and over 2000 lots were sold The sediment supply was cut off to the spit and a good portion of the spit eroded away Building of the north jetty at the entrance to Tillamook Bay may have had something to do with it By the l950s the town was a ghost town Sand movement in the littoral zone along the coast is quite complicated and is determined by the cell the sediment is in Komar I992 Inland sand dunes border 140 miles of the 310 miles of coastline in Oregon Beach sand comes primarily from erosion of sea cliffs and sand delivered to the ocean from the rivers Cooper I958 The most extensive dune sheet is 55 miles long and approximately 2 miles wide and extends from Coos Bay to Florence It was declared the Oregon Dunes National Recreation Area in 1972 The dune sheet north of Ttllamook Head that extends to the Columbia River has formed mainly in the last 3000 years from sediment deposited from the river From Bandon on south alluviation has kept pace with sea level rise in the Holocene so the tide does not extend far inland North of Bandon there are many drowned valleys where the tide reaches many miles inland The city of Portland undergoes tidal in uences onboth the Willamette and Columbia Rivers and it is 100 miles from the ocean Coseisrnic subsidence noted in buried soils has been described in 15 estuaries from Seaside to Coquille Darienzo and Peterson I990 Also I4 turbidites formed on the continental shelf have been correlated to the buried soils in the estuaries Adams 1990 Largemagnitude subductionzone earthquakes are suggested to have uiggered both the subsidence and the turbidites The Coast Range province extends offshore to the base of the abyssal plain which is 70 miles west of Astoria and 40 miles west of Cape Blanco The continental shelf extends from the shore to approximately 600 ft depth The steeper continental slope descends to the abyssal floor at depths of 9000 ft The accretionary wedge of sediments makes up the continental slope The subduction zone formed by the intersection of the North American and Juan de Fuca plates is at the base of the continental slope The trench formed there is not visible for it is filled with sediments The main source of sediments is the Columbia River which has formed the 3500 square rnile Astoria fan which has filled the trench along the northern Oregon shore The Coast Range exhibits two large folds and many faults North of the 45th parallel the rocks are folded into an anticline technically an anticlinorium that is plunging to the north South of the 45th parallel the sedimentary rocks fortn a large syncline technically a synclinorium To the west of the divide there are over 50 large faults mapped Most of these faults have a northwest by southeast I T if 419quot ll trend but a few faults have an eastwest trend or a north east southwest trend Most of the faults are normal with the fault planes close to vertical Not many valuable minerals have been found in this province The only place in the state where oil and gas have been found is in the Coast Range Snavely 1987 The Mist gas field was discovered in I979 at the nonhern end of the province in Columbia County Over 40 billion cubic feet of gas has been produced from l8 wells in this field Most of the extractable gas has been removed and the eld is now being used as a storage facility for natural gas The reservoir is in clean sand in the Cowlitz formationand the structure is mainly an anticline with some faults Possibilities of oil have been noted at the southern end of the province in the Tyee formation Sub bituminous coal has been mined in the Coos Bay area from the Coaledo and Tyee formations Black sands on the beaches and terraces of the southern coast that have come from the erosion of the ophiolites in the Klamaths have been mined sparingly for gold platinum garnet magnetite chromite arid zircons Peterson et al I987 The lighter minerals of quartz feldspar and mica have been washed funher offshore onto the continental shelf About half of the mercury mined in the state comes from Douglas County and areas south where the marine sediments and the volcanic Fisher Fomia tion have been mined The Oregon coast is notedfor all of its stacks arches and caves Many of these features are formed in basalt especially along the north coast Haystack Rock at Cannon Beach is the most famous sea stack in Oregon and it is part of a basaltflowthat has differentially weathered more slowly than the surrounding mudsof the Astoria Fomiation The largest cave is the Sea Lion Caves just south of Heceta Head Willamette Valley Province The Vifi39lamet te Valley province is part of a lowland that stretches from just south of Eugene Oregon to Vancouver British Columbia This at elongated alluvial plain in Oregon is approximately l30 miles long and 20 to 40 miles wide Orr et al 1992 The elevation decreases from about 400 ft in the south to sea level in Portland Seventy percent of the population lives in the Willamette Valley which makes it the economic heart of Oregon This province is drained by the Willamette River the longest nonh fiowing river in the United States The Vfillamette Valley was under an inland sea until the Coast Range began to uplift The valley surface slowly emerged from the water starting at the south end and moving nonh By approximately 30 Ma the valley south of Salem was out of the water By 20 Ma the whole valley had been uplifted out of the seas The Scotts Mills Formation in eastern Marion and Clackamas Counties was the last marine formation created in the Vlfillamette Valley before the valley bottom was uplifted out of the water Miller and Orr 1986 The Molalla Formation in the same area was the first terrestrial formation of clastic sediments mudflows and tuffs that was formed after the withdrawal of the seas As the Coast Range and the Cascades were uplifting the oor of the Willamette Valley was sinking There are bedrock paleosols below the sediments in the valley that are up to 1500 feet below sea level The stratigraphy of the Willamette Valley is very simple It is a long trough of bedrock that is filled with sediment The bedrock is the same sequence of rocks found in the forearc volcanics and marine sedimentary rocks of the Coast Range Yeats et al 1991 North of Salem Columbia River Basalt lies on top of the forearc sequence These flows came into the valley from 16 to 12 Ma and travelled as far south as Salem The bedrock was exposed for a long time as evidenced by thick red soils paleosols that are present on the bedrock that is today buried by hundreds of feet of sediments The main sediments resting on the paleosols in the bedrock are clay and silt probably deposited from low energy streams and lakes in the Pliocene Above the finegrained sediments is a thick layer of gravels that has mainly come from the Cascades The upper unit of sediment is a layer of rhythmites of catastrophic flood deposits from the Missoula Floods 15300 to 12700 years ago Waiit 1985 Evidence of at least 89 floods has been found in Washington Atwater 1984 but in the Vfillamette Valley a record of only approximately 30 floods has been found Glenn 1956 Each of the rhythmites is a finingup sequence of sand to silts that were deposited out of the waters of Lake Allison the gigantic lake that lled the Willamette Valley to 350 feet elevation during each flood Allen et al 1986 The lake probably lasted about a week each time there was a ood Ermtics of exotic rocks suchas granite quartzite and argillite have been found in the valley to 350 feet elevation Allison 1935 They were probably icerafted during each of the Missoula Flood events and melted near the upper water levels of the ood The largest erratic is found near Sheridan in Yamhill County The most famous emitic was the Willamette meteorite that was found in West Linn and sold to the American Museum of Natural History in 1905 It is the largest American meteorite It probably fell on a glacier in Canada and was icerafted to Portland during one of the floods Allen et al 1986 Thick silt deposits on the hills around Portland are considered loess wind deposited silt that has blown out of the oodplains during the Quaternary Lentz 1981 At the nonhern end of the valley extension of the basin in the Pliocene and Pleistocene gave rise to basalt volcanism forming the Boring lavas These eruptions happened mainly in the last two million years in the Portland area Mt Sylvania Larch Mountain and Highland Butte are examples of Boring lava shield volcanoes Mt Scott Rocky Butte Mt Tabor and Kelly Butte are also examples of some of the one hundred Boring eruptions in the Portland area They are made of basalt flows and cinders Minimal mineral exploitation has occurred in the Willamette Valley Bauxite an important aluminum ore is found is low concentrations in the lateritic soils developed on the Columbia River Basalts in the hills surrounding the valley Iron has been mined from limoriite in Scappoose and Lake Oswego The iron mining of the Vantage Horizon paleosol in between two Columbia River Basalts in Lake Oswego was operative from 1867 to 1894 l iii v 12 GEOLOGIC AND PHYSIOGRAPHIC Paovmcas OF OREGON m References Adanis John 1990 Paleoseisrnicity of the Cascadia subduction zone evidence from turbidites off the OregonWashington margin Tectonics Vol 9 No 1 pp 569583 Allen lE Burns M and Sargent SC I986 Cataclysntr on the Columbia limber Press Ponland Oregon 21 I pp Allison I S I982 Geology of pluvial Lake Chewaucan Lake County Oregon Oregon State University Studies in Geology l l 78 pp Allison I S I979 Pluvial Fort Rock Lake Lake County Oregon Oregon Deptarmient of Geology and Mineral industries Special Paper 7 7 pp Allison IS 1935 Glacial erratics in Villamette Valley Geological Society of America Bulletin Vol 46 pp 615632 Atwater BF 1984 Periodic floods from Glacial Lake Missoula into the Sanpoil area of Glacial Lake Columbia northeastern Washington Geology Vol 12 pp 464167 Bacon CR I983 Fxuptive history of Mount Mazama and Crater Lake Caldera Cascade Range USA Journal of Volcanology and Geothermal Research Vol I8 pp 57115 Baldwin EM I974 Eocene stratigraphy of southwestern Oregon Oregon Department of Geology and Mineral Industries Bulletin 83 40 pp Beeson MH Perttu R and Pentu 1 I979 The origin of the Miocene basalts of coastal Oregon and Washington an alternative hypothesis Oregon Geology Vol 11 No I0 pp l59 l66 Beeson MH Tolan T L and Anderson J L I989 The Columbia River Basalt Group in western Oregon geologic structures and other factors that controlled Ilow emplacement patterns In Reidcl SP and Hooper PR eds Volcanism and tectionism in the Columbia River floodbasalt province Geological Society of America Special Paper 23 9 pp223 246 Bishop E M 1989 Smith Rock and the Gray Butte complexOregon Geology Vol5 No4 pp 7580 Bowen RG Peterson NV and Riocio lF I978 Low to intermediate temperature thermal springs and wells in Oregon Oregon Deptartrnent of Geology and Mineral Industries Geol Map Series GMSI0 Brooks HC and Ramp L I968 Gold and silver in Oregon Oregon Department of Geology and Mineral lndustries Bull 6 337 pp Catchings RD and Mooney WD I988 Crustal structure of the Columbia Plateau evidence for continental rifting Joumal ofGeophysi39cal Research Vol 93 Bl pp 459474 Chan MS and Dott RH 1983 Shelf and deepsea sedimentation in Eocene foreari basin Western Oregon fan or nonfan American Association of Petroleum Geologists Bulletin 67 pp 21121 I6 Chitwood L A and McKee E H I98 I Newbeny Volcano Oregon US Geolog ical Survey Circular 838 pp 85 9l Cooper WS I958 Coastal sand dunes of Oregon and Washington Geological Society oflmerica Memoir 72 163p Darienzo ME and Peterson CD l990 Episodic tectonic subsidence of late Holocene salt marshes northem Oregon central Cascadia rriargin Tectonics Vol 9 No I pp I22 Dicken S N I980 Pluvial Lalte Modoc Klamath County Oregon and Modoc and Sisltiyou Counties California Oregon Geology Vol 42 No1 I pp I79I 87 Duncan RA and Iulm LD I989 Plate tectonic evolution of the Cascades anc subduction complex In Vintertt39 EL Hussong DM and Decker RW eds Decade of North American Geology The Eastern Pacific Ocean and Hawaii Vol N pp 413438 Duncan RA 1982 A captured island chain in the Coast Range of Oregon and Washington Journal ofGeophysical Research Vol 87 pp l0827 l0837 Eaton G P 1984 The Miocene Great Basin of western North America as an extending backarc region Tectonophysics v I02 pp 275295 Ferns ML and Huber DF I984 Mineral resources map of Oregon Oregon Department of Geology and Mineral Industries Geological Map Series GMS 36 Glenn lL I956 Late Quaternary sedimentation and geologic history of the north VVlll391TlCH6 Valley Oregon Unpublished PhD Dissertation Oregon State University 23 pp Gray 3 1986 Native terranes of the central Klamath Mountains California Tectonics Vol5 No7 pp I043I054 Hammond PE 1979 A tectonic model for evolution of the Cascade Range in Arrnentrout lA Cole MR and TerBcst H eds Cenozoic Paleogeography of the Westem United States Society of Economic Paleontology and Mineralogists Paci c Section Pacific Coast Symposium 3 pp 219237 Hotz P E 1971 Plutonic rocks of the Klamath Mountains California and Oregon US Geol Survey Prof Paper 648B pp BlB20 Hunter RE Clifton H E and Phillips R L I970 Geology of the stacks and reefs off the southern Oregon coast Ore Bin Vol32 No10 pp I8520 Irwin WP 1977 Review of Paleozoic rocks of the Klamath Mountains In Steward JH Stevens CH and Frische AE Eds Paleozoic Paleogeography of the Westem United States Pacific Coast Paleogeography Symposium Vol I pp 44154 Jones D L Silberling NJ and Hillhouse l 1977 Wrangellia A displaced teriane in northwestern North America Canadian Joumal of Earth Science Vol I4 pp 25652577 Kittleman L R I973 Guide to the geology of the Owyhee region of Oregon University of Oregon Museum ofltlatural Hist Bull2l 6p Komar PD 1992 Ocean processes and hazards along the Oregon Coast Oregon Geology Vol 54 No I PP 3I9 Lentz RT I981 The petrology and stratigraphy of the Portland Hills Silta Paci c Northwest Ioess Oregon Geology Vol 4 I No I pp 3I0 McBirney A 1978 Volcanic evolution of the Cascade Range Annual Reviews in Earth Science No 6 pp 437456 Mclnelly GW and Kelsey HM I990 Late Quaternary tectonic deformation in the Cape AragoBandon region of coastal Oregon as deduced from wavecut platforms Joumal of Geophysical Research Vol 95 No BS pp 66996713 Miller PR and Orr WN I986 The Scotts Mills Formation MidTertiary geologic history and palcogeography of the central Western Cascade Range Oregon Oregon Geology Vol 43 No I2 pp I39l5l Orr EL OIT WN and Baldwin EM I992 Geology of Oregon 4th edition KendallHunt Publishing Co Dubuque Iowa 254 pp Otto B R and Hutchinson D A I977 The geology of Jordan Craters Malheur County Oregon Ore Bin v I9 no8 pp I25I40 Pessagno EA and Blome CD I990 Implications of new Jurassic stratigraphic gcochronornetric and paleolatitudinal data from the western Klamath terrmc Smith River and Rogue Valley subterrancs Geology Vol I8 pp 655668 Peterson CD Gleeson GW and Wetzel N I987 Stratigraphic development mineral sources and preservation of marine placers from Pleistocene terraces in southern Oregon USA Sedimentary Geology Vol 53 pp 203229 Peterson NV and Groh EA 1964 Diamond Craters Oregon Ore Bin Vol26 No 2 pp I732 Priest GR I990 Volcanic and tectonic evolution of the Cascade volcanic are central Oregon Journal of Geophysical Research Vol 95 No B I2 pp l9583 l9599 Reidel S P Tolan T L Hooper PR Beeson MH Fecht lR Bentley RD and Anderson lL 1989 The Grande Ronde Basalt Columbia River Basalt Group stratigraphic descriptions and correlations in Washington Oregon and Idaho In Reidel SP and Hooper PR eds Volcanism and tectionism in the l il r GEOLOGIC AND PHYSIOGRAPHIC PROVINCES OF OREGON 13 Columbia River oodbasalt province Geological Society ofAmerica Special Paper 239 pp 2 52 Reilinger R and Adams l 1982 Geodetic evidence for active landward tilting of the Oregon and Washington coastal ranges Gi opr39ivrical Research letters Vol 9 No 4 pp 40l 4O3 Retzillack G I 1991 A field guide to midTertiary paleosols and paleoclimatic changes in the high desert ofcentral Oregon Part l Oregon Geology Vol 53 No 3 ppt 5t 59 Rytuba J l I989 Volcanisrn extensional tectonics and epitherrnal mineralization in the northem Basin and Range province Califomia Nevada Oregon and Idaho US Geol Survey Circular I035 pp 59 ol Rytuba JJ and McKee E H 1984 Perkaline ash low tuffs and calderas of the McDcm1itt volcanic field southeast Oregon and north central Nevada journal nfGeopt39ivsical Research Vol 89 No BIO pp 86168623 Silberling NJ and Jones Dl eds I984 Lithotectonic terrane maps of the North American Cordillera US Geol Survey Open File Report 84523 Smith Gary A I987 The in uence of explosive volcanism on fluvial sedimentation The Descuhutes Fonnation Neogetie in central Oregon Journal Sed PeI v 57 no 4 pp 613629 Snavcly PD I987 Tertiary geologic framework neotectonics and petroleum potential of the OregonWashington continental margin In Scholl DW Grantz A and Vedder JG eds Geology and Resource Potential of the Continental Margin of Wstern Nonh America and Adjacent Ocean BasinsBeaufort Sea to Baja California CircumPaci c Cowicil for Energy and Mineral Research Earth Science Series Vol 6 pp 305335 Snavely PD and Wells RE 1991 Cenozoic evolution of the continental margin ofOregon and Washington US Geological Survey Open le Report 9l44B 34 pp Snavely PD Wagner HC and Lander DL I980 Interpretation of the Cenozoic geologic history central Oregon continental margin crosssection Geological Society oftmerica Bullelin Part I Vol 9 pp l43 l46 Taylor EM I990 Volcanic history and tectonic developrrient of the central High Cascade Range Oregon Journal of Geopnvsirol Rerearch Vol 95 No B12 pp 1961149622 Vallier T L and Brooks H c cds 1986 Geology of the Blue Mountains region of Oregon Idaho and Washington US Geol Survey Prof Paper I435 93 pp Waitt RB Jr I985 Case for periodic colossal Jokulhlaups from Pleistocene Lake Missoula Geological Society of America Bulletin Vol 96 No l0 pp 12711286 Walker G W ed i990 Geology of the Blue Mountains region of Oregon Idaho and Washington Cenozoic geology of the Blue Mountains US Geol Survey Prof Paper 1437 135 pp Walker G W 1979 Revisions to the Cenozoic stratigraphy of Hamey Basin southeastern Oregon US Geological Survey Bulletin 1475 34 pp Walker GW and Nolf B 1981 High Lava Plains Brothers fault zone to Hamey Basin Oregon US Geological Survey Circular 838 pp l05 l I l Walsh FK and Halliday WR I976 Oregon Caves discovery J exploration Grants Pass Te CumTom Publishing 29 pp Wells R E and Heller P L 1988 The relative contribution of accretion shear and extension to Cenozoic tectonic rotation in the Paci c Northwest Geological Society o America Bull 1 10 pp 325338 Wong lG Silva WJ and Madin lP i990 Preliminary assessment of potential strong ground shaking in the Portland Oregon metropolitan area Oregon Geology Vol 52 No 6 pp l3I l34 Yeats RS 1989 Current assessment of earthquake hazard in Oregon Oregon Geology Vol 51 N0 4 pp 9092 Yeats RS et 21 I99 I Tectonics of the Vfillamette Valley Oregon US Geological Survey Openfile Report 9l44lP 47 pp 14 GEOLOGIC AND PHYSIOGRAPHIC PROVINCES or OREGON
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'