Geology 101 Exam 2 Study Guide
Geology 101 Exam 2 Study Guide GEO 101
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This 10 page Study Guide was uploaded by Carter Cox on Tuesday February 23, 2016. The Study Guide belongs to GEO 101 at University of Alabama - Tuscaloosa taught by Keene in Spring2015. Since its upload, it has received 109 views. For similar materials see Dynamic Earth in Geology at University of Alabama - Tuscaloosa.
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Date Created: 02/23/16
Where do magma and lava come from? - Magma comes from inside the earth - Lava comes from outside the earth What are the ways magma forms, and how does each work? - Decrease in Pressure o Heat makes rock melt (pressure) o Pressure keeps the rock together o Same heat and less pressure = melt o Pressure happens due to plate tectonics - Adding Volatiles o Evaporate easily o Water is a volatile o Adding volatile makes the evaporation easier o Adding volatile to rock (mostly H2O) makes melt temperature decrease therefore rock melts sooner o Volatile are released from the crust - Heat Transfer o Heat comes up and melts what is above it (Hawaiian Islands Moving) o Decrease in pressure o Adding volatile What are the major types of magma and how/ why are their compositions different? - Felsic o Pink and whit in color, your able to see visible grains o High silica content - Intermediate o “Middle” composition between felsic and mafic o Gray colored - Mafic o High amount of pyroxene, amphibole, and Ca- rich o Dark near black in color - Ultramafic o Very dark commonly green - Why? Their compositions are different because of the silica content and which melts first and last What does the Bowens reaction series tell us about magma formation? - Shows us the order in which minerals form out of melt Why does magma flow and what affects viscosity? - Flow o Because hot things rise o Less dense than solid rock o Squeezed by pressure - What affects viscosity (resistance to flow) o Heat- more heat more flow o Volatile- more volatile more flow o Silica- less silica more flow What are the differences between intrusive and extrusive rocks? - Intrusive rocks o Inside the earth - Extrusive o Outside the earth How do geologists classify igneous rocks? - Composition and texture o Felsic/ intermediate/ mafic/ ultramafic - Texture o Aphanitic Fine grained Cool quickly o Phaneritic Coarse grain Cool slowly o Porphyritic Large crystal with smaller background 2 stages of cooling o Glassy No crystals Very fast cooling Vesicular Cools so fast the gases get trapped o Pyroclastic Volcanic Contains pieces of broken rock In what areas are igneous rocks formed - Subduction zone o Continental arc Felsic o Island arc Mafic - Hotspots - Continental rift zones o Magma- felsic first than mafic - Mid ocean ridge o Mafic - Igneous Provinces o Runny ketchup like magma o Very low viscosity mafic lava Which rock types makes up most continental crust? Most ocean crust? - Granite for continental - Basalt for ocean crust What are the products of volcanic eruptions? What are their characteristics? - Lava - Pyroclastic Material - Gas - Geological Deposits/ rocks What are the main types of lave and why are they different from one another - Basaltic (mafic is runny) o Subtypes Pa hoe hoe Ropey A’a’ Jagged Pillow Lava being squirted in underwater vent - Andesitic o Thick flow (really slow) - Rhyolitic (felsic) (peanut Butter) o Mound up into lava dome because of its thickness What are the differences between the types of eruptions we studied? - Effusive o Low viscosity o Lava is basaltic - Explosive o Lots of pyroclastic debris o Trapped gas explodes What are the main features of a volcano? - Magma chamber o Filled with molten rock - Crater/ fissure o Big hole/ long crack - Vent - Flank Vent o Vent on the side of a volcano - Fumarole o Gas vent - Caldera o Collapsed magma chamber What are the major types of volcanoes? What are their Characteristics? - Sheild Volcano o Low and made of many lateral flows o Mild erruptions o Low viscosity lava o Found on ocean hot spots - Scoria Volcano o Made out of basaltic lapilli pile o Steep sides, deep crater o Symmetrical o Geologically short lived - Strato Volcano o Large steep sides o Alternating layers of lava and pyroclastic material Where do volcanoes occur? - Mid Ocean Ridge o Mafic lava o Sheild volcanoes here - Subduction Zone o Island arc o Strato volcano Gasses from seduction zone o Japan o Continental Arc o Explosive because thicker magma and andesitic lava - Continental Rift Zones o Lots of felsic material o African rift zone - Hot Spot o Area of the globe where heat comes out of the mantle - Oceanic Hot Spot o Ex. Hawaii o Lava is mafic o Eruption type: effusive - Continental Hot Spot o Ex. Yellowstone o Lava is felsic o Eruption is explosive (thick lava) - Flood Basalts o Massive flows from very fluid lava cover vast areas What are the volcanic hazards covered? What are their Characteristics? - Lava o Slowly takes over an area - Pyroclastic Flow o 100- 300 Km/h (flows super fast) o full of poison gas - Ash and Lapilli o Toxic glass shards o Blunt trauma o Aircraft - Blast itself - Landslides o Move up to 250 km/h o Billions of tons of material - Lahar o Water mixed with ash (snow) o Travel over 50 km/h - Earthquakes o Most all major eruption have these - Poison Gas o Can occur with or without eruption o Lake Nyos - Tsunami o Large volume of water caused by blast or collapse can be more damaging than blast What factors help us predict a volcanic eruption? - Earthquake activity o Increases before blast - Heat flow o Increased heat can cause landslides - Volcano shape o Bulges - More gas and steam What are options when it comes to stopping/ protecting ourselves from a volcano? - Determine danger of each volcano - Active o Currently erupting - Dormant o Hasn’t erupted lately, but geologically active - Extinct o Not geologically possible to erupt How to volcanic eruptions affect climate? - High altitude dust may block sunlight o Creates cooler climate - Large eruptions can affect planet - In deep time had profound effect Are there volcanoes elsewhere in the solar system? What are they like? - Extinct o Moon o Mars (Olympus mons) Largest volcano - Active o Io (Jupiter moon) o Saturn Moons What are all the steps in the process of weathering and erosion? - Weathering - Erosion - Transport - Deposition - Lithification What are the principle agents of erosion? - Liquid Water o Most common - Ice o Rare but effective - Wind o Only smaller particles o Cant pick up big things What are the major types of weathering and how are they different from one another? - Physical o Biologically Plant- microbes Animal o Jointing Change in heat and pressure o Frost wedging o Salt wedging Deserts and coasts Abrasion Glaciers, wind, water - Chemical: chemical composition is altered or rock is dissolved o Dissolution Water (and acids within) dissolve mineral All rain is acidic o Hydrolysis Chemical reaction between water and mineral New minerals form o Oxidation Mineral combines with oxygen New mineral forms o Hydration Water absorbs into mineral Expansion breaks up rock o Biological Fungi, lichen, and plants secrete acid What factors affect weathering rates? Why? - Ice - Where its flowing - Chemical processes - Why? Bowens reaction series says mineral weather at different rates How do different size grains act during entrainment, transportation, and deposition? - Entrainment o Act of lifting a particle from a position of rest to be carried in wind or current o Not determined by only size o Has more energy - Transportation o Energy determines the size of the grain because the mineral is being picked up and moved - Deposition o Energy determines size (larger particles/ grains means the less energy) o Deposited somewhere - Why? o Explains why sediments are found in different places o Helps reconstruct past environments o What the earth looked like during a time in history. What are the products of weathering? - Sediments o Loose fragments of rocks or minerals o Includes shells - Soil o Sediment mixed with organic material Why are there different types of soil? - Controlled by: o Parent rocks and minerals o Water content o Climate (heat/ humidity) o Local vegetation o Age How do geologists classify sedimentary rocks? - Detrital - Biochemical - Chemical How are bed, strata, and formation related to one another? - Bed: is a single deposit of sedimentary rock - Strata: layered beds together o Both can be various sizes Know the common stratigraphic structures we covered in class and what they tell us about the rocks in which they are found? 1) Ripple Marks / Dunes a. Indicate moving air or water b. Ripples= small c. Dune= large d. Ripples and dunes can determine flow direction 2) Cross bedding a. Always moving b. Sand piles up then falls to the bottom of the dune c. Layers in different directions 3) Desiccation Cracks a. Which kind of chemical weathering is causing this i. Hydration 4) Graded beds a. Sudden change in water velocity b. Underwater landslides, storms, deltas i. Must be created in a water environment 5) Trace Fossil a. Anything an organism has left behind i. Footprints, burrows worm feet Know the environments of deposition we covered in class. What kinds of rocks would form in each environment? - Environment in which sediment was deposited 1) Glacial a. Glacier = river of ice i. Moves any size grain ii. Glacial till 2) Mountain Stream a. Fast moving water i. Carries small grain away ii. Conglomerates 3) Annual Fan a. Change in velocity i. Arkose (feldspar) – doesn’t last long ii. Conglomerate 4) River a. Heavy grains roll, small grains float b. Flood deposits c. Sandstone, siltstone, mudstone (mudcracks) 5) Lake a. Low energy b. Mudstones c. Varves (fine grained beds) d. Delta at incoming stream 6) Sand Dunes a. Beach and Desert i. Small grains blown away ii. Well sorted limestone iii. Ripple marks and cross bedding What is the significance of a sedimentary basin? - to provide both a source of sediment and a relatively low place for the deposition of that sediment. What do transgressions and regressions tell us? - Transgression o Geologic event during which sea level rises relative to the land and the shoreline moves toward higher ground, resulting in flooding o Can be land sinking or ocean basins filling with water - Regression o Area of submerged seafloor are exposed above sea level Why does sea level change? - tides change this changing the sea level
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