Exam 2 Study Guide
Exam 2 Study Guide GEO 101
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This 21 page Study Guide was uploaded by Cassidy Reid on Monday March 9, 2015. The Study Guide belongs to GEO 101 at Washington State University taught by Wilkie in Spring2015. Since its upload, it has received 181 views. For similar materials see Introduction to Geology in Geology at Washington State University.
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Date Created: 03/09/15
Exam 2 Study Guide Wilke What is chemical weathering converts minerals and rocks into altered solids solutions precipitates types of chemical weathering hydrolysis oxidation dissolution types of physical weathering exfoliation frost wedging thermal expansion exfoliation plutons split into sheets along joints that lie parallel to the mountain face frost wedging breakage from expansion of freezing water in cracks thermal expansion expansion and contract heat and cool hydrolysis conversion of silicates to clay with water dissolution minerals dissolve in water mostly salts and carbonates ACID RAIN oxidation rusts iron mixtures with oxygen Factors that control weathering climateweather length of exposure How does composition of rock affect weathering Big rocksgranite are slow because no planes of weakness Layered sedimentary is fast because planes of weakness Factors that affect soil forming processes climate composition slope wetness time vegetation 3 classes of sedimentary rock elastic biochemical chemical when does clastic rock form when weathering erosion transportation deposition lithification when does biochemical rock form when organisms die and shells are lithified it gg5rm when does chemical rock form when minerals are precipitated out of solution form under recrystallization forms from the evaporation of ocean or saline lake waters How is the sorting rounding size of particles affect by wind only transports the finest particles How is the sorting rounding size of particles affect by water depends on the energy level if there is higher levels can move boulders and round them out over time what are the Sedimentary Structures cross graded ripple marks mud cracks what do sedimentary structures tell us transportation or weathering that was used to create that sedimentary rock Cross bedding layers at an angle because of wind and water form by water or wind and formed by direction of the wind blowing Graded bedding grains get coarser as depth increases because of turbidity currentwater High energy input gtlow energy look for coarse to fine coarse to fine ripple marks wavy lines formed on bed of sand because of waveswater Can form from wind or water Water shallow but it will be A symmetrical wind can be gentle or steep types of sedimentary environment continental transitional marine Depositional environment for coal swamp depositional environment for limestone marine depositional environment of sandstone transitional What are evaporates thick salt deposits because of precipitation of saline water form in lake 2 types of pressure confiningall directions directedspeci c direction Contact FOLIATION Metamorphism igneouspluton intrusion convergent and hotspots Regional NO FOLIATION Metamorphism deep burialmountain building convergent Hydrothermal Metamorphism hot water percolates through spaces in rock divergent and hotspots Burial Metamorphism weight of overlying rock plate interiors Shock Metamorphism meteorite impact no boundary Recystallization Crystal changes shape size but not mineral makeup Changes a parent rock goes through as metamorphic grade is increased Temperature increases so does grade Mudstone slatephylliteschistgneiss What are index minerals minerals that form under specific pressure temp conditions therefor us the metamorphic grade of rock its inside Difference between high grade and low grade metamorphism low grade may contain some of parent vs high grade with no parent rock Absolute dating finding age of rock through radiometric dating provides ages in years radiometric dating measuring ratio of parent to daughter to determine the age of rock half life uses unstable radioactive isotopes to determine absolute age The radioactive isotope the parent isotope evolves into a decay product the daughter isotope at a certain rate relative dating trying to put rocks in correct order without knowing age through stratigraphy stratigraphy correlationclassification of strata in sedimentary rocks Provides sequence of events form which relative dates can be calculated how is foliation created BOTH directed pressure and heat principle of superposition rocks get older with depth principle of cross cutting relationships the geological feature cutting is always younger than the feature it cuts 3 Unconformities Disconforrnity Nonconforrnity Angular Unconforrnity Disconformity rock above and below are parallel Lithologic correlation matching rocks of the same character from one place to another Fossil Assemblange relative dating Parent rock of quartzite sandstone Parent rock of marble limestone parent rock of hornfels mudstone Eras oldest to youngest Paleozoic540 mill Mesozoic251 mill and Cenozoic65 mill What is stress force acting on a rock Compression stress rocks pushed together convergent Tension stress rocks pulled apart divergentcontinental rifts shear stress rocks shift past eachother transform what is strain deformation response to stress where rock changes shape I L quot Ilia i Anticline arch upward syncline arch downward juu u a n a 2 nu H w J a EPIH 13339 anew H H H Hang 3 IH 1 r P Fl h H1 H 55 a H H H Me inully1n u H l l J x E l g 1 l U H H i U 174 I i J 3 1 I Luu 2quot n an a a MD HEB quotj quotaquot an r quot 1 I U H L L n D H 39d39 u I39 ErE a n o H HI Han quot M W H lands E L Equot quot395 g I l l an a H a 1 plunging anticline U or V shaped basin upright bowl Basins are caused by compression and downwarping Elastic Deformationstrain rock will return to former shape after stress released Plastic Deformationstrain deformed permanent but will not break Brittle Failurestrain crack fracture faults Difference between a fault and a joint A fracture that forms in a rock but unlike a fault the rocks on either side of a do not move Normal fault hanging wall moves down relative to the footwall reverse fault hanging wall moves up relative to the footwall a39uuei39l Parsi x F n A L Ct 1 quotg1 39Em5n39339 39z39l ua 39 f 39rula Mil r r r J Hugmica Wire 5 Symmetrical Fold fold split in half still symmetrical asymmetrical fold one side leaning overturned fold folds tilted what boundary is at the Appalachian mountains convergent what boundary is at the himalayas convergent why is weathering important produces soilsculpts earths surface chemical weather that would affect granite hydrolysisfeldspar turns to clay chemical weather that would affect basalt hydrolysis chemical weather that would affect limestone dissolution How does the climate affect the development of the soil pro le rainfall and warmquicker least developed soil cold tempsno rain which one would you nd the thickest accumulation of organic matter in soil the top level What is diagenesis all procceses that createalter sedimentary rock Index Fossil used to identify the relative age of a rock unit used in stratigraphic correlation of rock units from one location to another what kind of rocks can be dated directly igneous and metamorphic How does oil and gas form the accumulation of organic matter on the sea oor what are the two types of gas traps Anticline trap and Fault trap How did dino39s go extinct meteorite What is a stream gradient the slope of a stream What do countour lines tell us the closer together they are the deeper the slope the further away they are what form did early life take 35 mya bacteria prokaryotes event on paleozoicmesozoic boundary mass extinction 90 of marine and 70 of land animals Ancestors to modern man appeared how many years ago 100000 yrs ago Dome upside down bowl Domes are caused by compression and uplift Much like a cone What sedimentary rock is the most abundant Clastic In which of the following climates will chemical weathering be the slowest cold and dry What type of weathering would affect a marble statue Dissolution What type of metamorphism is associated w convergent plate boundaries and mt building regional Which of the following sequences describes the metamorphic changes in a mudstone or shale with decreasing metamorphic grade Gneissgt Schist gt Slate gt Unconformity Markers of missing time deposition of rocks isn39t continuous forever Radiometric absolute age dating works best with which rock type Igneous How do we get fossils Usually rapid burial is required Examples Soft mud Rivers Flood deposits Volcanic ash What makes a good index fossil Unique and easy to identify Lived for a Short period of time preferably only thousands to hundreds of thousands of years They were w in two hundred or 10000 years from win each other Widely Distributed Can tell you time w in the world Geologic Time Scale Eons Eras Periods and Epochs Broken down Geologic time scale oldest newest Precambrian Paleozoic Mesozoic Cenozoic Precambrian from birth of Earth 46by up to before complex life forms developed greater than 543 my algae bacteria some fossils without shells like jellyfish Paleozoic ancient life 251543 mya fish trilobites clams corals ferns Mesozoic age of middle life 65251 mya dinosaurs 1st small mammals Cenozoic recent life 065 mya mammals humans Phanerozoic last 543 million years Which geologic time period covers approximately 88 of all geologic time span Precambrian What was the name of the impact crater in the Yucatan Peninsula Mexico Chicxulub crater Joint Faults Brittle failure results in cracks or fractures in rocks If NO movement has taken place along the fracture it is called a joint Strikeslips faults Side to Side Horizontal Motion Result of shear stress Leftlateral Rightlateral DipSlip faults Motion is updown vertical along the fault plane caused by compression or tension Reverse compression 0 The easiest way to determine the type of vertical motion is to see a crosssection side view 0 Based on relative motion 0 Draw a stick figure across the fault plane Folds result from compression Weathering Physical Frost wedging Expands Roots actual tree roots in rock separating and moving the rock 39EXfOliatiOIl example Large cracking sheets Mechanical or physical weathering breaks material into smaller pieces creating more and more 0weathering is breakdown of rocks Where do the heat and pressure come from Convection gives up energy Temp increases as you go deeper and deeper The pressure also increases because you have gravitational weight oiling up What happens when rocks get buried When they heat up oMinerals or grains in the rock may become deformed Deformationz If buried deep enough the rock can undergo plastic deformation Diffusion The movement of atoms due to thermal energy heat forming new minerals Fluids are released ex ClaymicahH20 Recrystallizationz Crystals can grow larger or change shapes Rocks become weaker and easier to deform Regional metamorphism Mudstone gtshale gtslategtphyllite gtschistgtgneissgtmigmatite Quartz parent rock Sandstone Marble parent rock Limestone Hornfels parent rock fine grained mudstone Coal parent rock Compressed Organics Types of Metamorphism Contact regional Hydrothermal Burial Shock Contact Metamorphism Heat from rising igneous intrusions metamorphose preeXiting rocks oLowHigh Temperatures oLow Pressures Regional Metamorphism Metamorphism caused by deep barial or tectonic forces that increase temperature and pressure over broad regions 0 LowHigh Temperatures 0 LowHigh Pressures Hydrothermal Metamorphism Hot water percolates through spaces in rocks 0 High Temperatures 0 Low Pressures Burial Metamorphism Rocks are metamorphosed by the weight of overlying rocks Confining pressure 0 Low Temperatures 0 Low Pressures Shock Metamorphism Meteorite impact Extremely high temperatures and pressures 0 Look for Stishovite shock quartz polymorph of quartz often fractured due to impact Why are sedimentary structures so important Clues to past environments you can tell about climate movement of air and water earth history Uniformiantarianism The present is the key to the past Lithi cation hardening of soft sediments into rock 0Compaction pore space volume is reduced due to weight of overlying sediment andor Cementation chemically precipitated minerals in pore spaces acts as a glue by binding the materials together common cements Calcite silica hematite Glacial ice and sorting Least selective Results in poorly sorted sediments Large range in particle sizes Could be as big as a house or small like clay Note Lack of bedding or other structures Most sorting of detrital elastic grains takes place during transportation
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