Exploring Planet Earth
Exploring Planet Earth GEOL 101
Popular in Course
Popular in Geology
verified elite notetaker
This 11 page Class Notes was uploaded by Thad Will on Sunday October 25, 2015. The Class Notes belongs to GEOL 101 at University of Nevada - Las Vegas taught by Staff in Fall. Since its upload, it has received 30 views. For similar materials see /class/228638/geol-101-university-of-nevada-las-vegas in Geology at University of Nevada - Las Vegas.
Reviews for Exploring Planet Earth
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: 10/25/15
UNLV GEOL101 Lecture Outline Fall 2009 102709 Structural geolo y A tectonic and other forces deform the earth s crust B structural geologists 1 observe the results of deformation 2 attempt to unravel the events responsible 3 predict subsurface features between data points a outcrops b drill hole data c geophysicalinvestigations C structures include faults 2 folds 3 joints 4 foliation D practical importance 1 subsurface structures can trap petroleum 2 design of major construction projects a possible weakness in the rock mass 3 earthquake safety ll Rock deformation A deformation 1 change in the volume or shape of a rock unit 2 occurs in response to application of stress 3 strain a measure of how much deformation occurs b usually expressed as a percentage B stress 1 force that acts on a rock unit 2 changes shape or volume of the rock 3 confining stress a applied by the load of overlying rocks b acts uniformly in all directions 0 also called hydrostatic pressure d leads to a reduction in volume e makes rocks more ductile bend rather than break 4 differential stress acts in a direction b often in addition to confining c compressional 1 pushes on the rock unit 2 rocks are strong under oompression d tensional 1 pulls the rock unit apart 2 rocks are relatively weak under tension e shear 1 two opposing directions 2 tears the rock C types of deformation elastic a rock returns to original volume and shape when stress is removed 103009 UNLV GEOL101 Lecture Outline Fall 2009 b small deformations are usually elastic 2 plastIc a rock will flow and take on a new shape that is permanent b likely to occur when rock is hot under confining pressure 3 brittle a rock breaks when stressed common at earth s surface no confining pressure D laboratory testing we can recreate heat confining pressure stresses 2 we can not recreate geologic time a we can only surmise effect of time on deformation b we do know that fast deformation is more likely to cause brittle failure than slow deformation Mapping structure A most geologic structure is hidden beneath ground B we explore structure by a variety of means 1 geophysical investigations 2 drill hole data 3 outcrop data C data is used create maps of subsurface information 1 topographic maps of given rock layers 2 cross sectional maps of structure foldsfaults D surface mapping 1 done on outcrops of sedimentary rocks data is collected on the orientation tilt of layers sedimentary rocks should have been initially horizontal deformation tilts and deforms sedimentary layers dip and strike are measurements of tilt maximum angle of inclination from horizontal measured with an inclinometer measured on planar geologic features a bedding plane b fault c contact between two units d joint lTl 9 ritUsmwrv F strike 1 map direction in which the feature itself extends 2 intersection of a dipping plane with horizontal forms a line 3 map direction of that line is the strike IV Joints A fractures along which no appreciable displacement has occurred B joints form 1 during cooling of lava a shrinkage creates vertical cracks like in mud b intrusions oool slowly much less cracking 2 in response to unloading a erosion excavation glacial melting b parallel to stress reduction 3 tectonic forces a apply shear tensional forces b joints tend to form in roughly parallel sets 103009 UNLV GEOL101 Lecture Outline Fall 2009 1 sets are oriented according to stresses 2 commonly 2 or more distinct joint sets C joints are important 1 rock strength 2 groundwater flow 3 cavern formation 4 subsequent mineral deposition V Faults A basics 1 fractures in the earth s crust that display evidence of differential movement ie the two sides have shifted with respect to each other 2 sudden movement along faults causes most earthquakes 3 most faults are inactive B evidence of movement 1 offset scarps long low steep cliffs exposed at the surface slickensides polished and striated fault surfaces fault gouge ground up rock fragments mylonite a metamorphic rock b stretched and elongated grains c hard to identify C categories of faults Dipslip a primary movement along dip of the fault surface b hanging wall fault block above a dipslip fault c footwall fault block below a dipslip fault d normal fault 1 hanging wall drops with respect to footwall 2 indicates tensional stresses a stretching during uplift b horizontal tension pull apart 3 common in western US reverse fault 1 hanging wall rises with respect to footwall 2 results from compressional stress 3 forces hanging wall to override the footwall 4 associated with folding and complex mountain building 5 common in the Alps Appalachian mountains f thrust fault 1 a reverse fault with a very shallow dip angle 2 have moved rocks more than 50 kilometers 3 can place older rocks on top of younger ones 2 strike slip a primary movement is horizontal along strike b movements is either leftlateral or rightlateral 1 stand on one fault block 2 look across to the other side 3 if the other block has moved to the right it is a rightlateral fault San Andreas 3 transform faults 0quotquot F J e v 103009 UNLV GEOL101 Lecture Outline Fall 2009 a largest strikeslip faults b occur along plate boundaries 1 eg San Andreas fault 2 moved 560 KM in the last 30 million years D landforms caused by faulting 1 graben a block drops down between two large normal faults b produces elongated valle s c valleys are bounded by uplifted blocks called horsts d eg East African Rift Valley 2 faultblock mountains a sedimentary rocks tilt on subparallel normal faults 1 hanging wall drops at the fault 2 the back side of the block tilts up b builds rugged mountains quickly 1 Grand Tetons created in 510 million years 2 also responsible for the Sierra Nevada and mountains of the Basin and Range Province 3 fault zones a rather than a single fracture large strikeslip faults consist of fault zones of roughly parallel faults b may be kilometers wide and 100 s of KM long c individual movements usually occur in a part of the zone not all of it d rocks tend to be beat up and may weather and erode faster than the surrounding rock e create long surface features that are often visible from the air 1 valleys 2 vegetative changes 3 altered drainage patterns VI Folds A basics 1 during mountain building flatlying sedimentary and volcanic rocks are often bent into a series of undulating folds 2 folds usually occur in groups 3 occasionally a single fold is encountered B terminology 1 sides of a fold are called limbs 2 limbs are separated by the axial plane a imaginary surface b passes through the points of maximum curvature within the fold axis a imaginary line drawn along the crest of the fold b described by a map direction and plunge which is analogous to dip 4 symmetrical fold a both limbs dip at about the same angle 5 asymmetrical fold a limbs dip at different angles 6 overturned fold 103009 C D 7 UNLV GEOL101 Lecture Outline Fall 2009 a at least one of the limbs is rotated past vertical recumbent fold a at least one of the limbs is rotated past vertical to horizontal types of folds 1 anticline a fold formed by upwarping of rock b if you were to slice one horizontally 1 you would find the oldest rocks in the center 2 outcrop pattern points in the plunge direction syncline a fold formed by downwarping of rock b if you were to slice one horizontally 1 youngest rocks are in the center 2 outcrop pattern points away from the plunge 3 groups of folds a limbs of a syncline are likely to also be limbs of adjacent anticlines and viceversa b folds have a locality of maximum intensity die out further away 4 monoclines a broad flexural features 1 only one limb 2 eg Colorado Plateau b thought to result from vertical faulting at great depth in what is referred to as the basement rock 5 domes a surface sedimentary layers upwarped to form domes 1 broad upwarping of basement rock 2 igneous intrusions 3 buoyant migration of salt b if you were to slice a dome horizontally 1 bullseye pattern 2 you would find the oldest rocks in the center c softer sedimentary rocks can erode eg Black Hills 1 leave an igneous or metamorphic core 2 resistant rock layers create meandering ridges called hogbacks 6 basins a downwarping of the basement rock b thought to result from weight of the overlying sediments c if you were to slice a dome horizontally 1 bullseye pattern 2 find the youngest rocks in the center d basins tend to be large with very gentle dips 1 makes them difficult to identify in the field 2 eg Michigan Basin landforms associated with folds 1 synclines do not necessarily form valleys nor do anticlines necessarily form rId es 2 actual landforms result from differential weathering of the rock units 3 crest of anticline may be shattered a weathers easily 103009 UNLV GEOL101 Lecture Outline Fall 2009 b Cushing anticline 103009 UNLV GEOL101 Lecture Outline Fall 2009 102009 Glaciers A definition 1 slowly flowing ice mass a semipermanent features b cover 10 of the Earth39s surface 2 glaciers originate on land from the accumulation of snow a above the snow line b more snow fails then melts 3 come in two main types valley and continental B valley glaciers 1 relatively small features in mountain valleys a tend to follow existing stream valleys b end in either the ocean or by melting on land 2 may be 10039s of meters thick 3 there are thousands of these in existence a North America has lots 1 high mountains 2 lots of precipitation some even in Africa New Guinea C continental glaciers 1 ice sheets a continental scale features that cover a land mass b may be gt3000 m thick c only two ice sheets are in existence today 1 Greenland 2 Antarctica d covered much of the earth in the geologic past 2 ice shelves a extension of an ice sheet cap into the open ocean b Antarctic shelves are 100 s of meters thick c smaller shelves at some Canadian islands D ice caps 1 refers to ice located at the polar regions 2 Antarctic ice sheet and shelves make up the southern cap 3 the northern cap is over water and is not a glacier ll How glaciers grow A snow accumulates and gets buried 1 consistent low temperatures 2 plenty of snow 3 temperature is more important a some places get lots of snow b snow melts each year so no accumulation 4 need more snow to fall than melts B changes into ice as it ages and gets buried 1 evaporation 2 recrystallization Hi How glaciers dissipate A loss of ice is called ablation B mechanisms for loss of ice 1 melting 2 breaking up into icebergs called calving 101609 UNLV GEOL101 Lecture Outline Fall 2009 3 sublimation 4 wind erosion this would be hard to separate from sublimation C balance between ablation and accumulation a if ablation exceeds accumulation glacier retreats b if accumulation exceeds ablation glacier advances D retreats can be dramatic as glaciers and shelves can break apart during retreat 1 huge chunk broke off the Antarctic ice shelve in 1995 and 2002 2 1995 break include an 80 km long iceberg IV How glaciers move A plastic flow 1 ice depth reaches about 50 meters 2 confining pressure allows plastic deformation 3 microscopic ice particles slip past one another 4 gravity is the driving force 5 dominant mechanism in bitterly cold regions 6 flow within a glacier is like a stream only slower a velocity is slow cmday b fastest in the center and near the top c friction along bottom and edges slows flow B basal slip 1 thin layer of water at the bottom of the glacier 2 can result from either pressure or temperature 3 water acts as a lubricant to the moving ice 4 in valley glaciers basal slip can lead to a period of fast movement called a surge C crevasses 1 top surface is not under confining pressure a brittle b it fractures rather than flows 2 resulting crevasses may be 50 m deep a not likely to close suddenly like in movies b often covered by snow bridges 3 valley glaciers a curves b changes in slope V Glacial erosion A importance 1 streams are the most important erosional agent on earth 2 glaciers are the most powerful 3 glaciers are very important during ice ages B glacial abrasion 1 ice is heavy 2 contains rock fragments 3 essentially grinds the rock down a polished rock b striations 1 groves cut in bedrock 2 show direction of advance 4 valley glaciers grind the valley walls a sides steepen b tops collapse c fall on glacier 101609 UNLV GEOL101 Lecture Outline Fall 2009 C plucking 1 process of lifting and moving intact blocks a frost wedging causes the block to rise b block is then lifted plucked c incorporated into the glaciers load 2 blocks can be transported up to hundreds of miles 3 individual blocks may be huge house size VI Erosional glacial landforms A ice sheets 1 flow over everything but significant peaks 2 tend to smooth off the existing topography 3 bedrock knobs a gentle slopes pointing towards the source steep slopes in the direction of movement B valley glaciers create some of the most spectacular landforms on earth a tend to follow stream valleys 1 hollow out a U shape 2 side walls collapse on top of glacier 2 erosion is a function of glacier thickness a main glaciers cut deep valleys b tributaries shallow ones 1 form hanging valleys 2 spectacular waterfalls 3 cirque a head of a valley glacier b bowl shaped feature in the mountains crest c great for skiing 4 arete a sharp ridge between cirques 5 horn a multiple cirques can leave a very steep spire b Matterhorn a steep flooded valley formed by glacial erosion b unlike streams glaciers can cut below base level c ocean levels drop during glacial periods 7 loch ness a valley glacier gouged out weak rocks along a fault zone b the moraine plugged the end c lake is 23 miles long 1 mile wide averages 600 feet deep Vll Depositional glacial landforms A glaciers carry a huge load of sediment 1 all sizes are carried with equal ease 2 particles are not sorted by size within the glacier B when the glacier melts that load is dumped 1 material of all sizes 2 called glacial till C glacier is like a conveyor belt 1 builds up a hill at the end point 2 called an end moraine a destroyed during glacial advance 101609 UNLV GEOL101 Lecture Outline Fall 2009 b glacial retreat leaves a series of these c upper Midwest is covered by moraines d Long island is an end moraine 3 lateral moraines are found along the sides of glaciers D eskers 1 streams along the underside of meting glaciers 2 carry sand and gravel 3 makes sort of an upside down river bed called an esker 4 long winding hill of sand and gravel E glaciers calve icebergs on land during retreat ig chunk or ice is left behind 2 glacier deposits sediment around the ice 3 leaves a kettle lake 4 Michigan Wisconsin are covered in these Vlll Glacial outwash melt water runs across the glacial till 1 erodes the till 2 carriers finer particles away 3 deposits them elsewhere as glacial outwash B wind picks up the finest smallest material 1 grinding of the glacier creates lots of rock flour 2 can be carried long distances by wind 3 deposited as a fine dust called loess 4 makes fertile farmland a Illinois Nebraska Missouri b large portions of China IX Ice ages A currently ice covers about 10 of the earth s land B in the past around 30 was covered C North America 1 ice sheets advanced over the continent 2 evidence of four major episodes a named after the southernmost deposit b Nebraskan Kansas lllinoian Wisconsonian D effects of ice age 1 numerous plants and animals went extinct 2 drainage patterns changed significantly a the Missouri river used to flow north b the Great lakes were originally river valleys 1 glaciers scooped out much of the rock 2 receding ice left big depressions behind 3 weight of the glaciers compressed the underlying rock a these areas are now rebounding upward b Cleveland rises a little each year 4 sea levels dropped dramatically 13O m a water was transferred into the ice sheets b exposed much of the sea floor to erosion opened land bridges between continents 5 Pluvial lakes a the climate was generally wetter than it is today b great lakes formed in Utah Nevada Washington 1 Great Salt Lake is a remnant a water evaporated 101609 UNLV GEOL101 Lecture Outline Fall 2009 b the dissolved materials remained 2 Pyramid lake is less salty c many pluvial lakes were dammed by glaciers 1 dams eventually broke 2 huge floods carved gorges 3 Truckee Columbia rivers 6 drowned river valleys a sea level dropped b rivers to the ocean carved downwards c river valleys are now drowned Chesapeake bay X Permafrost A soil that remains continually frozen 1 up to 500 m thick 2 covers about 25 of the earth 3 Alaska northern Canada Siberia Tibet B near surface layer may thaw during the summer C headaches 1 drainage stinks a surface layer is swampy 2 thawing the soil a buildings roads etc add heat b soil loses its strength 3 huge problem for the Alaska pipeline a oil must be hot to flow b pipe below ground 1 had to be insulated 2 sometimes even refrigerated 3 construction changed water flow c at the ground surface 1 base had to be insulated 2 interferes with wildlife d caribou migration 101609
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'