GEOLOGY TEST 3 STUDY GUIDE
GEOLOGY TEST 3 STUDY GUIDE 80176 - GEOL 1010 - 001
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80176 - GEOL 1010 - 001
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This 18 page Study Guide was uploaded by Ryan Jakszta on Saturday March 19, 2016. The Study Guide belongs to 80176 - GEOL 1010 - 001 at Clemson University taught by Alan B Coulson in Fall 2015. Since its upload, it has received 199 views. For similar materials see Physical Geology in Environmental Science at Clemson University.
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Date Created: 03/19/16
GEOL 1010 Dr. Coulson TEST 3 STUDY GUIDE Highlight= Important Principle Highlight= Key Term **Geology in the News: Ice Cores being taken from Atlantis Massif Insight on history of earth and life on other planets Former Clemson Geology major is a researcher Lecture 9: Climatology Why do we care? Climate change: changing conditions on earth can affect where we live, available resources, etc Studying ancient climate helps predict future trends Climate Basics Climate average surface conditions over some long period of time Usually want at least a decade of data Weather average surface conditions over short period of time Ex: days, seasons, etc Climate is determined by complex interactions between lithosphere, atmosphere, biologic processes, ocean circulation, etc Feedbacks change in one component of system affects other things that change original component Positive feedba change in 2nd component enhances change in first Component A increases, so B increases, which again causes A to Increase, etc Ex: more soil➡more weathering➡more soil➡etc * A can decrease and still enhance B* Ex: temp (A) lowers➡more glaciers (B) Runaway train effe continuous cycle of positive feedback can be hard to break, and could continue until a component can’t change anymore or something else affects it Negative feedback change in 2nd component offsets 1st component Steps: 1. A increases➡ B decreases 2. B decreases ➡A decreases 3. A decreases➡ B increases 4. B increases➡ A increases Seesaw effect increase➡decrease➡increase➡etc Stabilizes the two components What Controls the Climate? sun=main energy source Insolation INcoming SOL ar radiATION Varying insolation➡varying climate 1. Orbital parameters a. Vary earth’s distance from sun=vary amount of insolation b. Sun is not directly in center of earth’s orbit c. Aphelion farthest orbital from sun (~152 million km) d. Perihelion closest orbital from sun (~147 million km) * perihelion/aphelion do NOT control winter vs summer* e. Milankovich cycles cycling changes in earth’s motions in space (3 main) ● Eccentricity earth’s path oscillates from more to less circular ~100,000 years for one full cycle (max➡min➡max) Influences warming/cooling trends during ice ages ● Obliquity aka ‘Tilt’ tilt on earth’s axis changes angle ~41,000 years for one cycle Affects seasons Why we have opposite seasons in N/S hemispheres Seasonal contrast changing obliq. angle changes temp contrast between summer and winter High angle/contrast = hot summer and cold winter Low angle/contrast = more moderate Eccentricity can also affect contrast (see powerpoint) ● Precession ‘wobbling’ of earth on the axis Spinning motion (unlike obliquity, which is rocking) 22,000 years for complete cycle Determines which hemisphere is pointed toward the sun 2, Atmosphere First thing that insolation encounters Troposphere lowermost layer Where most weather phenomena occur ~30% insolation reflected back into space Albedo measurement of reflectivity varies with material 4% ground, 6% atmosphere, 20% clouds Atmosphere composition Nitrogen78%, Oxygen21%, Carbon Dioxide, Water, etc<1% Greenhouse gases trap insolation close to earth’s surface, and some energy is reradiated back into space Greenhouse gases slow this process and as a result, warm earth Called greenhouse effect * GGs might be in small %, but they trap a lot of insolation Removing all GGs ➡ 33°C lower temp Insolation changes with latitude At equator given amount of insolation covers relatively small area because it strikes earth perpendicular to surface Same amount insolation covers large area at poles Explains why poles are colder Energy imbalance on earth Processes redistribute excess energy Heat transport: several cells help move heat energy away from equator and toward poles Hadley Cells transport heat from equator ±30° lat. Works a lot like convection Steps 1. Insolation warms the air close to the ground 2. As it rises, it begins to cool and gets pushed aside by warmer air from beneath it a. Creates low pressure at the equator 3. As air mass cools, some water vapor cools (rain) a. Why equator has rainforests/lots of rain 4. Pushed aside air moves N/S 5. Cools as air moves N/S➡loss of water vapor 6. By the time air mass ~30° lat, it is dense enough to sink to earth’s surface a. Creates high pressure at surface b. Little rain 7. At surface, air absorbs more insolation and heats up as wind until it rises again a. Some wind blows N or S Ferrel and Polar cells operate same way at different latitudes All 3 interlock El Nino periodic changes in wind strength over pacific during some winters Affect global weather patterns Normal pacific conditions: West Pacific Warm Pool (WPWP) area of warm water in Pacific (near Australia, on equator) Normal winter conditions 1. Trade winds push water west 2. ‘Void’ left is filled by cool water upwelling east 3. WPWP heats air above it, causing air to rise a. Creates low atmo. Pressure above it 4. Rising air cools causes lots of rain a. Like beginning of Hadley cells W Pacific is warm/wet, East is cool/dry El Nino Winter conditions 1. Trade winds weaken/stop 2. WPWP flows back to east 3. Eastern waters become warm, so upwelling stops 4. Low pressure area MUST follow warm water (warm water creates it) a. Southern oscillation resulting flipflop in air pressure between west/east 5. Rain MUST follow low pressure area W Pacific is cool/dry, East is wet/warm El Nino effects Quasi periodicity of once every 47yrs Scientists know what happen during El Nino, but don’t know why trade winds occasionally weaken and cause one La Nina trade winds strengthen instead of weaken Opposite effects of El Nino Ex: eastern pacific gets cooler/drier than usual ** Geology in the News : New study suggests oxygen buildup on earth might have started during Archean Eon instead of Proterozoic 1.8 billion years earlier The Hydrosphere All of the water on earth Water has high heat capacity Ex: Gulf Stream brings warm water from gulf or Mx. to Europe Use ocean currents to help Thermohaline Circulation on map: red (hot)=surface, blue (cold)=floor of ocean Why does water sink in N Atlantic? Colder water results in denser water and higher salt concentration (makes it heavier) In recent decades, we’ve noticed that the process is slowing down Due to overall higher temp of earth Glaciers (fresh water) melting and diluting water Negative feedback loop (some balancing occurs) The Biosphere Plants Draws down carbon dioxide for photosynthesis Affects albedo (measures reradiation) Animals Release carbon dioxide and methane Biological Pump how biosphere moves carbon to Lithosphere Interaction of biosphere, atmosphere, hydrosphere, and lithosphere The Cryosphere All snow/ice on earth Ice covers ~9% of land surface (varies on seasonal basis) Most land surfaces albedo ~1525% snow/ice albedo ~4090% The Lithosphere Tectonics affect climate in many ways 1. Continental position a. Close to equator, poles, etc 2. Continent size a. Pangea (most continents joined together) was dry, arid, desertlike 3. Collision zone uplift a. Creates rain shadows mountains act as barrier/wall to prevent lots of precipitation to move past it i. Ex: Washington State 4. Land bridge land acts as a bridge between two continents a. Ex: Latin America b. Affects ocean currents Recording Climate instruments/records only go back so far Tells us how climate could change in future Air trapped in glacial ice Records how atmosphere was when the ice was frozen Ice cores from Greenland + Antarctica>2 miles (3300 meters) Some represent > 1 million years Main way to study carbon dioxide levels Proxies substitute of some type Different proxies record different aspects of climate at different times * ice bubbles were NOT proxies* Rules/types 1. Consider nature of proxy a. Ex: rings on a tree i. Know type of tree and how they grow 2. Biogeography study of where plants/animals live a. Finding fossils in different areas i. Can give data very different from today 1. Ex: Canada has crocodile fossils 16 17 18 Stable isotopes (ex: types of oxyge O ,O ,O Measure as ratio ( O /O 16 Bigger # always on top Different atomic weights: different amounts of each isotope get incorporated into molecules Ratio in some materials changes with climate variables Oxygen isotopes Many invertebrates/plankton shells Can provide quantitative paleotemperature data Very precise Able to see temp change 18 16 Ex: O /O in fish bone reflects water temp when fish was alive fish Fish equation: T = 111.4 − 4.3 (Df − Dw) * Df = ratio in fish bone Dw = ratio in seawater (1.0) T = water temp (degrees C) Some trace metals in shells Ex: Mg/Ca replace each other Depends on temp Why do we want multiple temp proxies? Confirm other calculations Stable ca13on 12otopes good for plants/construction of environment C / C : ratio in animals skeletons reflect type of plant in ecosystem Both isotopes form carbon dioxide Plants take in both types of carbon dioxide for photosynthesis 13 12 Amount of C / C depends on photosynthesis style C3 vs C4 plants: both doing photosynthesis, just in different ways * C3 and C4 do NOT refer to isotope; they refer to plant type C3: cooler, wetter climates; C4: hotter/drier climates Lecture 10: Global Warming Is Earth Warming Up? Must consider different locations, daily/weekly measurements, graph methods, etc Simple proxy to test: glaciers Are they getting smaller? As seen in pics, it looks like they are Since we have reached this conclusion, we now ask why Why is the Earth Warming? 1. Earth is currently naturally warming a. Coming out of most recent ice age b. Natural processes account for ~50% of warming for past few centuries i. Ex: Milankovich cycles 2. Unusual warming pattern a. Warming is occurring faster than ever before and with greater magnitude i. Humans have been adding lots of greenhouse gases to atmosphere since Industrial Revolution in 1800s (greenhouse effect) Specifically carbon dioxide, methane, and nitrous oxide GGs are steadily decreasing amount of insolation that earth has Scientists have ‘concluded’ that ~50% of temp increase for the past ~200 years is a result of GG buildup Is the GG buildup anthropogenic (manmade)? Increase in world population can lead to increase in GG buildup Carbon dioxide buildup Mona Loa Curve Shows that carbon dioxide has increased over years, but no indication as to why/how Higher now than ever in past 400K years Where is the carbon dioxide coming from? Carbon isotopes Different sources release different isotopes Volcanoes emit C13, forest fires release C14 and C12, etc Suess effect decline in atmospheric C14/C12 ratio For there to be a decline, that means that either less C14 or more C12 Unlikely that C14 has changed, since it is created at a relatively constant rate Therefore ,C12 must increase Fossil fuel burning can cause this; it emits a lot of C12 without any C14 * the Suess effect strongly supports anthropogenic hypothesis because burning fossil fuels is the only thing that accounts for the C14/C12 drop ** for those that don’t believe in GW, you must find an alternative to the Suess effect Summary: humans are increasing carbon dioxide levels, and carbon dioxide helps increase temp, so it is concluded that humans are responsible for some of the current warming Regardless of whether or not you believe in it, we still have to deal with the results Possible effect of GW: Ice sheets melting Rising sea levels Aridity in mid latitudes Stronger hurricanes/El Ninos extinctions Seven Global Warming Myths 1. Flooding Coasts a. As glaciers melt, water will flow into oceans and cause sea levels to rise i. Although true, it will happen on decadalcentury timescale ii. Threat is not imminent 2. Planet is burning up ‘An Inconvenient Truth’ movie shows accurate data but makes it seem worse Although accurate, some maps are designed to make you agree with message 3. Record low temps disprove GW Data is accurate but does not support a disproving of GW Temps from one area instead of around the world Reflect one small length of time Data about record highs/norms is not included We don’t base climate trends on data from one area People using this are typically talking about weather instead of climate 4. Who cares if its only 3 degrees? Scientists predict a 3 degree increase © for the next century 3 degrees C is 5.4 degrees F (slightly larger difference) 3 degrees is on a global scale: temps in specific areas will change much more Last ice age was only ~4.5 degrees C lower global temp then today Imagine what 3 degrees hotter would be Many organisms (some of which we rely on) would not survive 5, Scientists can’t decide between GW or cooling 1975 National Academy of Science Report stated that warming or cooling is possible, but was inconclusive Also in 1975 a reporter stated that global cooling data was in high volume Reporters often mess up words and thus become unreliable sources 6. Scientists profit from GW Grant money does not go into a scientist’s pocket All spendings are monitored and documented 7. Professionals antiGW people tell you to not trust the scientists that study this change Why would you not believe them?? Lecture 11: Deserts Desert Basics and Processes Why do we care? Deserts cover a lot of area on earth and are growing 20% of land is desert 15% is semiarid What is a desert? Temp is NOT criteria Lack of rainfall is key (<10in/yr) There are a lot of deserts, and some are even larger than the USA Found in specific latitudes (~30°N or ~30°S) Atmospheric Hadley Cells Also found in other areas Shadow zones do not get a lot of rain Size of land mass can cause less rainfall as well Central EurAsia large area away from Coast Polar Regions also considered deserts Very little precipitation per year Glaciers built slowly over time Weathering in deserts Little chemical weathering (due to little rainfall) Slow process oxygen/iron oxides Causes characteristic red/brown rock color Erosion Water still important More of a flashflood scenario No vegetation to restrain rainfall Arroyo shallow ditches that represent day streams, but during thunderstorms can fill up quickly and cause fast erosion Why hikers are advised to not hike in Them Wind erosion Can only move relatively small particles Wind has low density/viscosity particles>~0.06mm in diameter hard to move Unless in tornado (but unlikely) Can STiLL add up to a big volume Ex: Sahara Desert: 250500 million tons of dust transported to Atlantic each year Deflation erosion by removing only tiny particles Pavements result of deflation coarse , grainy surface Another misconception: only 20% of deserts are actually covered in sand Desert Features Ventifacts any object altered by exposure to wind erosion More than just rocks; plants, trash, etc. are still ventifacts Alluvial fans fanshaped sediment formed at bottom of arroyo Arroyos carry a lot of sediment and builds up at its end Found in other, nondesert areas, but those are formed different ways Playa lakes aka playas isolated lakes in desert (no rivers/streams leading to it) Depression filled with water (even empty at times) that fill during storms White ring around playas Saturated mineral deposits that were left behind when water started to Evaporate Halite = good example Inselberg large body of rock randomly in a desert Like icebergs Plutons do not weather easily Arches columns of rock that support an arch/bridge Result of localized erosion Arches National Park (Utah)(2000+) Form by cracks seeing a lot of erosion Erosion is typically centered on/around cracks Do not last forever; the arches can fall/crack Dunes wind deposits of sand Dunes move over time Started by surface of irregularities (rock on ground, stick, etc) Saltation jumping/skipping action as wind pushes sand Types of dunes Important factors: wind direction, sand availability, and vegetation 1. Barchan Dune crescent moon shape a. Stereotypical dune b. Horns point toward direction the wind blows 2. Transverse Dunes string of Barchan Dunes attached by horns a. Must have a lot of sand supply b. One dominant wind direction 3. Linear Dunes aka longitudinal long, relatively straight a. Crests are parallel to wind, NOT perpendicular (unlike 1&2) b. Not a lot of sand available 4. Star Dune starshape from above a. Wind direction constantly changing 5. Parabolic Dune U or Vshaped (not crescent) a. More vegetation present b. Coastal areas (not always in deserts!) c. Horns point toward where wind is coming from *Know how to identify Dunes by picture, know how to see which way the wind is from/towards, and how to differentiate between each type Desertification Process of an area becoming a desert Sahara expanding south ~30mi/yr 1 billion people in highrisk areas Why is is occurring? 1. Tectonics 2. Climate Change increasing temps/pressures can cause greater/lesser areas of precipitation 3. Human Activity livestock grazing, over farming, etc How can we prevent? 1. Not able to change tectonic movement 2. Difficult to change climates… 3. Less grazing, less clearcutting crops, less overcropping, etc. Lecture 12: Glaciers **Geology in the News: amount of water flowing into Earth’s interior strongly correlates to active faults Effects of Glaciers Why do we care? Problems with melting causes issues in ecosystems Sea level change If all glaciers melted, sea level would rise 200ft (65 m) Enough to completely cover florida Glaciers trap large amounts of water Coastline during ice age was much larger Isostatic depression crust warping downward due to ice East Antarctic 7.5 km deep Isostatic rebound (crustal rebound) glaciers melt and crust morphs back Changes thermohaline circulation Slows down process Drinking water and irrigation Ex: Washington gets ~470 billion gal/yr If glacier melts, there will be less over time * melting glaciers does NOT provide more drinking water* Glacier Basics Glacier large amount of ice that moves Ice currently covers ~9% of land area Antarctic = 85%, Greenland=10% Antarctic exceeds 4200m thick Formation 1. Granular snow slightly more dense snow; melted snow refreezes 2. Firn denser ice pellets 3. Glacial ice compressed firn; high density a. ~ 50 m is when a ‘glacier’ can be used as a term Requires time, coldness, and precipitation Glacier Types 1. Valley ‘mountain’, ‘alpine’, form in/around mountains and in valleys a. Can be very long and very thick , but are restricted to a specific area b. Found all around the world c. Ex: Mt. Kilimanjaro (Africa, ca 2000 ft) i. Ironic, because on equator 2. Continental ‘ice sheet’ much larger than valley glaciers a. Cover entire landscape (entire continent) Glacial advance and retreat Obvious in an ice age Accumulation more material produced (advance) Higher elevation, colder temps, etc Ablation where more melting occurs than freezing (retreat) Firn line ‘equilibrium line’ not always in middle Glacial movement Speed varies Ex: South pole flag post moving over time Types of movement 1. Plastic flow >50m thick small crystals at base of glacier start moving individually a. Very slow process 2. Basal slip under right temp and pressure conditions, you can form a small layer of water under base of glacier which causes slipping a. Faster than plastic flow b. Ex: slip n slide and ice skating Crevasse large cracks that form at top of glacier Breaks at top due to cold temp and low pressure (brittle behavior) Can be very hazardous Glacial Erosion Lots of sediment trapped in glaciers Abrasion material caught and ground up and carried with ice Plucking glaciers pick up larger bodies/objects Glacier moves over bump/hill and breaks up the hill as it goes over Mainly affects downhill side Features of movement Striations thin, straight, parallel lines carved into rock Ushape valleys glacier moved through area and left shape Hanging valley ushape valley leads into another valley * to identify, look for waterfalls, rapids, etc Cirque large, carved out area Tarns formed permanent lakes that develop Horn sharp, peaked mountain Form when multiple glaciers slide down different sides Arete ridge that separates horns Roche mountonee formed by plucking Large rock with one steep side Able to tell where from/where going glacier is Glacial Sediment Deposit Erratics carried boulder left in an area by a glacier Till extremely poorly sorted Outwash sediment being washed out by melted glacier More sorted than till Loess very well sorted, small particles Very good landscape for agriculture * STUDY HINT: don’t get depositional features and erosion features mixed up Depositional features Moraine large pile of sediment formed around edges of glaciers Eskers wavy pattern of sediment deposit Formed by outwash process at base (or underneath) glacier Drumlin asymmetrical shape (look like mountonee) Difference between drumlin and mount. Is formation Drumlin is pile of sediment, mount. Is solid rock Can also get ice flow direction, but is reversed (ice came from steeper side) Kames small, low hill of sediment Formed by broken up glaciers melting One kame means lots of kames in area Kettle lakes bodies of water formed in kames process
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