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This 6 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 82 views. For similar materials see Geology in Geology at Washington State University.
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Date Created: 10/26/15
Alanna Wight Quiz 2 Study Guide Geology 10103 Interlude B Chapters 6 amp 7 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 Ice 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
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