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This 10 page Study Guide was uploaded by Alanna Wight on Monday October 26, 2015. The Study Guide belongs to Geology 101 at Washington State University taught by Wilkie in Fall 2015. Since its upload, it has received 66 views. For similar materials see Geology in Geology at Washington State University.
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Date Created: 10/26/15
Exam 2 Study Guide Geology 101 Interlude B Chapters 67910 Interlude B A surface Veneer Sediments and Soil Why is weathering important 0 Because sedimentary rocks make up about 75 of our land surface 0 Produces soil for growing and food and forests o It sculpts and modifies the Earth39s surface responsible for all our landscape What is weathering and erosion how do they differ o Weathering is the process which rocks are broken down at the Earth39s surface 0 Erosion is the process that moves pieces of rock fragments and deposits them elsewhere Be familiar with the different types of chemical hydrolysis oxidation dissolution weathering and physical exfoliation frost wedging etcmany more weathering Chemical weathering Converts minerals and rocks into altered solids solutions and precipitates only occurs to those minerals exposed to the quotweatherquot 0 Hydrolysis The reaction of any substance to water example Feldspar forms clay o Oxidation A mineral reacts with oxygen to make a different product example Iron in minerals like pyroxene or hematite Fe203 o Dissolution Minerals dissolved by water or acids examples Halite or Calcite Physical weathering fractures rock breaks material into smaller pieces o Exfoliation form of mechanical weathering in which curved plates of rock are stripped from rock below 0 Frost Wedging the repeated freezing and thawing of water in areas with extremely cold weather When water freezes it expands What factors control the rate of weathering Ex Question Would a climate which has high rainfall and hot temperatures be more susceptible to slow moderate or fast weathering rates 0 climate length of exposure to rainfall and other climate factors 0 more susceptible to fast weathering How does the composition of the rock the minerals it is composed of affect weathering What type of chemical weather would affect granite think feldspar or basalt mafic minerals pyroxene and amphibole or limestone o If the rocks is composed of more magic rocks it will weather faster than if it were felsic 0 Granite Hydrolysis o Basalt Oxidation o Limestone Dissolution How does the climate affect the development of the soil profile Where would you find the least developed soils Which one would you find the thickest accumulation of organic matter 0 Higher temperatures and more rainfall means more weathering and thinner soils so it affects it negatively If you have medium rainfall and medium temperatures you will have better soil o In a wet tropical climate o In a temperate climate Chapter 6 Pages of Earth s Past Sedimentary Rocks What is sediment and where does it come from A sediment is the product of weathering from other rocks and minerals What are the 3 classescategories of sedimentary rock and under what conditions do they form What is the most abundant sedimentary rock type group Clastic moving waters beach tides rivers or streams Chemical Marines and deserts Biochemical Deep sea reefs continental margin or shelf 0 Clastic For clastic rocks be able to recognize sorting and rounding differences What do these textures indicate about the sediment transport distance When the rocks are finely sorted and more round it has traveled a far distance from the origination When the rocks are coarse and more angular the closer they are to origination How is the sorting rounding and size of particles affected by the agent of transport wind water ice Wind very fine sorting small particles and rounded Water Somewhat fine sorting small to medium particles and rounded ce Least selective sorting can move house sized particles more angular What does the energy level of a river indicate about the maximum particle size that can be transported The energy level of a river if it is fast can move larger rocks and some boulder If it is slower it will move just smaller particles What are sedimentary structures What information do they provide Bedding parallel layers of sediments each layer is called a bed Cross bedding sets of bedded sediment at an angle to horizontal deposited by currents example Dunes Graded bedding Beds progress from coarse grains at bottom to fine grains at top of bed Mudcracks polygonal pattern of cracks that develop in mud cracks that develop in mud as it dries example mudflats Bioturbation burrow marks left in sediments by animals Be familiar with the different kinds of sedimentary environments What environment would limestone form in Coal Sandstone with large scale crossbedding What are evaporates and what environment would they form in Continental clastic environment includes streams deserts and lake glacial Evaporites salts form as water evaporates from shallow basins and sandstone Shoreline clastic domains includes shoreline deltaic tidal flat and beach Marine clastic chemical biochemical includes continental shelf continental margins reefs deep sea How does sediment become a sedimentary rock What is lithification and diagenesis 1 Weathering becomes clasts breaks down rocks 2 Erosion 3 Transportation 4 Deposition when moving waterwindice settles out clasts and accumulates Lithification hardening of soft sediments through compaction and cementation Buried clasts are squeezed tightly together compaction and then binds them together cementation Diagenesis The chemical process and physical changes that transform sediments into rocks You find an outcrop of sandstone that is composed of very well sorted and well rounded grains of quartz sand with symmetrical ripples What can you tell me about the environment of deposition traveled far ripples means it was formed by oceans Chapter 7 Metamorphism A process of Change What are the controlling factors of metamorphism Temperature heat pressure fluids hot water can transport ions chemical weathering What are the main types of metamorphism where do they occur geologically and what type of plate boundary are they associated with them if any Contact Metamorphism heat from rising igneous intrusions metamorphoses preexisting rocks Lowhigh temps low pressure Regional Metamorphism most common caused by deep burial or tectonic forces that increase temperatures and pressure over broad regions Lowhigh temps lowhigh pressures Hydrothermal metamorphism Hot water percolates through spaces in rocks high temps low pressures What is foliation What pressure condition is needed for its development What other factor determines if a rock will develop a foliation Will a limestone or sandstone parent rock develop foliation under directed pressure and a high temperature Why or why not How are these rocks classified texturally What is recrystallization o Foliation is the preferred orientation of platy flat or elongated minerals o Directed pressure is needed for its development 0 Yes intermediatehigh schist coarse grained Recrystallization is when crystals grown larger or change shapes Describe the changes a parent rock such as mudstone will undergo as the metamorphic grade is increased in terms of texture and rock name Do any new minerals form How does the new mineral size change with grade How does this relate to how the metamorphic rock is named Contact metamorphism takes place locally near igneous intrusions It is caused by low to moderate pressure intense heat and reactions to magma that is being metamorphosed When contact metamorphism takes place with mudstone or shale slate is formed The mudstone or shale is the parent rock or protolith What are index minerals How can they be used to constrain the temperature and pressure conditions of metamorphism Index minerals are characteristic minerals that define metamorphic zones formed under restricted range of temperatures and pressures example garnet Geologists use index minerals to determine the temp and pressure conditions of which metamorphic rocks formed What is the difference between highgrade and lowgrade metamorphism see Figure78 Low Grade low pressure and low temperatures may contain features of parent rocks High Grade high pressure and high temperatures features of parent usually destroyed Chapter 10 Deep Time How Old is Old and Interlude E Memories of Past Life Fossils and Evolution Know the difference between absolute and relative dates and how they39re determined Absolute dates determine event39s actual time Relative dates putting events in proper order Q Know and understandbe able to apply the principles of relative dating original horizontality superposition crosscutting relationships etc Law of Horizontality units deposited horizontally to gravity Law of Superposition undisturbed succession of sedimentary rock the oldest layers are on the bottom Crosscutting relationships an igneous intrusion is always younger than the rock it cuts across Inclusions are pieces of one rock unit that are contained within another it can be assumed that the rock next to the one including the units must be older to be able to provide the fragments Q Know each type of unconformities each type what do they represent and how they form Uncomformities markers of missing time Discomformity an uncomformity in which the rocks above and below the uncomformities are parallel Angular uncomformity after sediments are created there is uplift and turn angular and then there are more layers created at the top Noncomformity sedimentary rocks in contact with crystalline igneous or metamorphic rocks Q Understand how we correlate stratigraphic layers Stratigraphy is a branch of geology which studies rock layers strata and layering stratification Q Review Chapter 17 readings in the lab manual 711741 and practice exercises Figures 175 in lab manual Q You will be given an absolute dating problem Be sure you understand how to calculate an age given the number of parent and daughter or their percentage Q Understand the limitations and restrictions of absolute dating What kind of rocks can be dated directly Igneous and Metamorphic and NOT Sedimentary always broken down and made into new rock Q What is an index fossil What makes a good index fossil A fossil used to identify the relative age of a rock unit A good index fossil is unique and easily identifiable for a short period of time and is widely disturbed Q Geologic Time Scale Know the names and ages of the Eons Precambrian and Eras Paleozoic Mesozoic and Cenozoic You should be able to put them in relative order from oldest to youngest You should know what the dominate life from was age of the mammals age of the hard shell sea animals invertebrates age of the dinosaurs Eons phanerozoic and precrambrian Precrambrian from birth to earth up to before complex life forms developed gt543 million yearsshels got harder Phanerozoic last 543 million years Eras cenozoicrecent life O65mya age of mammals Mesozoic age of middle life 65251mya dinosaurs Paleozoic ancient life 251543mya shels got harder 0 Review the questions you answered for A very brief history of life on Earth as viewed from the fossil record lecture Key in on what happened or why the boundaries between Eon and Eras are place at that particular time What is the hypothesized event that caused the extinction of the dinosaurs When did it occur Where was it located Mass extinction possible meteor impact Chicxulub Crater Chapter 9 Crags Cracks and Crumples Crustal Deformation and Mountain Building and Interlude F Box F1 Q Be able to identify the different types of stress compression tension shear by the structures that result from each and what plate boundary situation is associated with each stress type Strain when a rock is stressed it may become deformed changing shape andor volume Plastic deformation permanent strain flows or bends Brittle failure permanent strain cracks or fractures faults Elastic deformation temporary strain goes back to original strain Q Be able to identify the different types of strain elastic plastic brittle and examples of structures formed by each Elastic temporary strain goes back to original from when stress is released Plastic permanent strain flows and bends folds Brittle permanent strain cracks or fractures faults Q What is the difference between a fault and a joint Be able to use the hanging wall and foot wall to differentiate between normal and reverse faulting Joint A surface or fracture in a rock without displacement parallel to the fracture Fault a surface of fracture in a tectonic plate Q What are the differences between symmetrical asymmetrical and overturned folds if the fold is split in half and both sides are symmetrical then it is a symmetrical fold if the fold is split in half and one side is different than the other then they are asymmetrical if the folds are tilted then they are overturned folds Q For the Appalachians Himalayas and Basin and Range mountains identify the type of structures one would expect to find and the type of plate boundary which created each one Appalachian convergent plate boundary Himalayas convergent boundary Basin special type of syncline Q Be able to recognize all structures presented as a map or a crosssection view given the age relationship and strike and dip symbols of the units Be able to name the type of structure nonplungingplunging anticline and syncline strike slip right and left lateral normal reverse thrust fault the type of stress involved the strain type and the type of plate boundary where each would form Anticline A shape Syncline U shape Right and Left lateral dipslip side to side horizontal motion transform Reverse compression dipslip vertical motion divergent and rifting Normal tension dipslip vertical motion divergent and rifting Non Plunging lines of sediment are straight do not bend Plunging lines of sediment bend Strike Slip direction and angle of anticlinesyncline Horizontal Fold Axis is non plunging Thrust Fault folds move older rock over newer rock creating double layers Q Understand how oil and gas form Why does oil and gas collect in certain areas What are the two types of oil and gas traps Oil and gas form from accumulation of organic mattersea shells microscopic organisms marine animals 1 Low Oxygen Supply organic matter does not decompose buried sediments undergo chemical reactions from increased temp and pressure max 130 celsius organics converted to gaseous compounds 2 Low densities low densities of oilgas allow them to migrate through permeable rock can be trapped under certain geologic conditions low permeability rocks prevent oil from escaping at earth39s surface Oilgas collect in an organic rich source to generate it Two types of gas traps 1 Structural traps hold gasoil because earth has been deformed in some waydome crease in rocks fault trap oilgas becomes trapped in impenetrable layer 2 Stratigraphic traps depositional in nature formed in a place often body of porous sandstonelimestone becoming enclosed in shale shale keeps oilgas from escaping difficult to migrate through shales Q Look over figures and block diagrams in the textbook and lab manual for additional practice recognizing geologic structures
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