GEO 101-007 Exam 4 Study Guide
GEO 101-007 Exam 4 Study Guide GEO 101-007
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This 14 page Study Guide was uploaded by Jennifer Gintovt on Monday November 9, 2015. The Study Guide belongs to GEO 101-007 at University of Alabama - Tuscaloosa taught by Dr. William Lambert in Summer 2015. Since its upload, it has received 218 views. For similar materials see The Dynamic Earth in Geology at University of Alabama - Tuscaloosa.
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Date Created: 11/09/15
GEO 101-007 Exam 4 Study Guide Chapter 14: Streams and Floods: The Geology of Running Water 1. _____ Water Table A. Occurs when a fluid flows in parallel layers, with no disruption between layers 2. _____ Stream B. Running water removes loose fragments of sediment 3. _____ Channel C. A trough dug into the ground surface by flowing water 4. _____ Flood D. Larger solid particles (sand, pebbles, or cobbles) that bounce or roll along stream floor 5. _____ Headward Erosion E. Water seeping through rock surrounding stream channel dissolves certain minerals and transports these ions down the stream 6. _____ Continental Divide F. Occurs when a fluid flows in parallel layers, with no disruption between layers 7. _____ Laminar Flow G. A ribbon of water that flows in a channel 8. _____ Scouring H. Refers to the maximum particle size a stream can carry 9. _____ Breaking and Lifting I. The process by which a stream channel lengthens up its slope as the flow of water increases 10. _____ Abrasion J. Small solid particles (silt or clay size) that swirl along in the water without settling to the floor of the channel 11. _____ Dissolution K. The boundary, approximately parallel to the Earth’s surface, that separates substrate in which groundwater fills the pores from substrate in which air fills the pore 12. _____ Dissolved Load L. Running water can break clasts of solid rock off the channel floor or walls, or may lift clasts of the channel floor 13. _____ Suspended Load M. A highland separating drainage that flows into one ocean from drainage that flows into another 14. _____ Bed Load N. Running water containing sand to gravel size particles acts like sandpaper and grinds away at the channel floor or walls 15. _____ Stream Competence O. An event during which the volume of water in a stream becomes so great that it covers areas outside the stream’s normal channel 16. _____ Stream Capacity P. Running water dissolves soluble minerals as it passes and carries the minerals away in solution 17. _____ Turbulent Flow Q. Refers to the total quantity of sediment it can carry (depends on competence and discharge) Draining the Land: • Precipitation (rain, snow, hail) brings water to land surface • Groundwater springs also bring water to the land surface • Gravity pulls surface water downhill into a stream channel, which is a trough in the surrounding substrate Stream Formation: 1. Precipitation (rain) occurs 2. Sheetwash flows downhill 3. Flowing water digs tiny channels called rills 4. Rills downcut; develop into streamflow Drainage Network (basin): • An array of interconnecting stream that together drain an area • 5 types o Dendritic o Rectangular o Trellis o Radial o Parallel • The geology (rock type) of land surface is the major control over the type of drainage network that develops Drainage Divides and Basins: • A highland or ridge that separates one drainage basin (network) from another 5. I, 6. M, 7. F, 8. B, 9. L, 10. 11sPe,r: .., ,2..J, 4.. C GEO 101-007 10/28/15 Permanent vs. Ephemeral Streams Permanent Streams: Ephemeral Streams: • Water flows all year • Do not flow all year • Bed/floor of channel is at or below • Bed/floor of channel is above the water table the water table • Humid or temperate climates • Dry climates o Sufficient rainfall o Low rainfall o Low evaporation o High evaporation • Discharge varies seasonally • Flows mostly during rare flash floods Stream Discharge: • Discharge = area of the stream times average stream velocity • Measuring water flow velocity can be difficult o Not all water flows through a stream/river at the same speed Erosion: • Efficiency of erosion is a function of velocity, volume, and sediment content of water o Small volume, slow-moving, clear water § Not efficient at erosion o Large volume, fast-moving, turbulent, sandy water § Very efficient at erosion o A lot of erosion can occur during a flood (more energy) How do streams transport sediment? • Geologists refer to the total volume of sediment carried by a stream as its sediment load. Sediment Deposition: • High energy (fast moving water) = sediment erosion/transportation • Low energy (slow moving water) = sediment deposition • Typically, stream/river energy decreases slowly. When this happens, the larger clasts (pebbles) are deposited first, then medium-size clasts (sand), and finally small clasts (silt/clay). Sorting occurs • Fluvial deposits (alluvium) – sediment deposited in a stream channel, along a stream bank, or on a floodplain • Point bar – a wedge-shaped deposit of sediment on the inside bank of a meander • Delta – a wedge of sediment formed at a river mouth when the running water of the stream enters standing water, the current slows, the stream loses competence, and sediment settles out Stream gradient: • The slope of a stream’s channel in the downstream direction • Longitudinal profile – a cross-section image showing the variation in elevation along the length of a river GEO 101-007 10/28/15 Base Level: • The lowest elevation a stream channel’s floor can reach at a given locality • Ultimate base level is sea level (sea level can move up and down o A lake represents a local base level o A stream “tries” to erode down to base level (slow process) In general, a stream cuts down into the ground in the headwaters and cuts from side to side near the mouth Meander: a snake-like curve along a stream’s course Alluvial Fan: • A gently sloping apron of sediment dropped by an ephemeral stream at the base of a mountain in arid or semi-arid regions Braided stream: • A sediment-choked stream consisting of entwined sub-channels Chapter 15: Restless Realm: Oceans and Coasts 1. _____ Bathymetry A. Low area between waves 2. _____ Abyssal Plain B. The bending of the waves as they approach the shore at an angle 3. _____ Seamounts C. As the lithosphere moves away from the mid-ocean ridge spreading centers it cools down and sinks, creating a flat section of ocean floor 4. _____ Current D. The elevation difference between sea level at high tide and low tide 5. _____ Coriolis Effect E. Time interval between passage of two successive crests 6. _____ Gyre F. A well-defined stream of ocean water 7. _____ Thermohaline Circulation G. Hot-spot volcanoes (non-plate boundary related) that do not rise above sea level 8. _____ Tidal Reach H. Top of the wave GEO 101-007 10/28/15 9. _____ Crest I. A deep, glacially carved, U-shaped valley flooded by rising sea level 10. _____ Trough J. Variation in depth 11. _____ Base K. A large, circular flow pattern of ocean surface currents 12. _____ Wave Refraction L. The rising and sinking of water driven by contrasts in water density which is due in turn to differences in temperature and salinity; this circulation involves both surface and deep water currents in the ocean 13. _____ Fjord M. The deflection of objects, winds, and currents on the surface of the Earth owing to the planets rotation What does crust have to do with oceans? • Compared to continental crust, oceanic crust is more dense, thinner, and younger • These differences result in the surface of the oceanic crust having a lower elevation than continental crust Ocean Floor Features: Passive Continental Margin: Active Continental Margin: • Continental shelf (wide) • Continental shelf (narrow) • Continental slope • Continental slope (steeper) • Continental rise • Trench Abyssal Plain Submarine canyons Seamounts Mid ocean ridges Passive Continental Margin: • Relatively shallow water • Relatively flat Answers: 1. J, 2. C, 3. G, 4. F, 5. M, 6. K, 7. L, 8. D, 9. H, 10. A, 11. E, 12. B, 13. I GEO 101-007 10/28/15 Active Continental Margin: • Deep trenches • Mariana Trench Ocean Water and Currents: • Salinity – the degree of concentration of salt in water Ocean Water Salinity Variation: • Ocean water salinity variation is a function of: o Water temperature (warm water can hold more salt) § Tropics are generally warmer due to more solar radiation § A large difference in water temperature with depth exists near the tropics § Warm water from tropics is transported toward the poles by currents o Addition of freshwater from river runoff, groundwater, ice melt, and direct rain o Evaporation rate at oceans surface o Ocean currents (fast moving vs. slow) § Surface Currents are caused by interaction between wind and the surface of water. Only affects the upper few hundred meters of water § Deep Currents are also influenced by wind due to zones of upwelling and downwelling Ocean Deep Currents: Rivers in the Sea • Upwelling- wind pushing water away from coast (southern wind) • Downwelling- wind pushing water toward the coast (northern wind) Wave Action: • Cause: shear of wind blowing over the water surface • Energy decreases with depth • Wave morphology: o Crest o Through o Base Longshore Current and Longshore Drift o Responsible for sediment transport along coast GEO 101-007 10/28/15 The Coastal Zone: • Beach- an accumulation of sediment found along landward margin of ocean Offshore Bars: • Submerged or partly exposed ridge of sand or coarse sediment that is built by waves offshore from a beach • Breaking waves dig into the sand near the shore creating trough • The excavated sand is deposited either on the beach or aside forming sandbar (offshore bar) Barrier Islands: • Offshore piles of sane built above sea level that is a result of high rate of sediment deposition due to wave and tide activity Estuaries: • An inlet in which seawater and river water mix, created when a coastal valley is flooded because of either rising sea level or land subsidence (sinking) • Bar-built estuaries o Form when a shallow lagoon or bay is protected from the ocean by a sand bar or a barrier island • Coastal Plain Estuaries o Formed at the end of the last ice age between 10,000-18,000 years ago. As glaciers receded and melted, sea levels rose and submerged low-lying river valleys Organic Coasts: • A coast along which living organisms control landforms along the shore • Coastal wetlands (salt marshes and mangroves • Coral reefs GEO 101-007 10/28/15 Chapter 16: A Hidden Reserve: Groundwater 1. _____ Groundwater A. Seep down into 2. _____ Water Table B. The region below the water table where pore space is filled with water 3. _____ Unsaturated Zone C. A mound of groundwater becomes trapped above a localized aquitard that lies above the regional water table 4. _____ Saturated Zone D. Sediment or rock that does not transmit water easily and therefore retards (slows down/stops) the motion of water (typically has both low porosity and permeability) 5. _____ Aquitard E. An aquifers that is separated from the Earth’s surface by an overlying aquitard 6. _____ Aquifer F. A location where water enters the ground and infiltrates down to the water table 7. _____ Confined Aquifer G. Water that resides under the surface of the Earth, mostly in pores and cracks of rock or sediment 8. _____ Unconfined Aquifer H. A spring that emits water ranging in temperature from 30-140 degrees C 9. _____ Perched Aquifer I. An aquifer that intersects the surface of the earth 10. _____ Infiltrate J. The region of the subsurface above the water table, pore space may contain some water and some air 11. _____ Recharge area K. Sediment or rock that transmits water easily (has high porosity and permeability) 12. _____Discharge area L. The potential energy available to drive the flow of a given volume of groundwater at a location; can be measured as an elevation above a reference GEO 101-007 10/28/15 13. _____ Hydraulic Head M. The boundary, approximately parallel to the Earth’s surface, that separates substrate in which groundwater fills the pores from substrate in which air fills the pores 14. _____ Oasis N. A verdant (green with grass, etc.) region surrounded by desert, occurring at a place where natural springs provide water to the surface 15. _____ Hot spring O. A location where groundwater flows back up to the surface, and may emerge at springs Karst Landscape: • A region by underlain by caves in limestone bedrock; the collapse of the cave creates a landscape of sinkholes separated by higher topography; or of limestone spires separated by low areas Porosity and Permeability: • Porosity – the total volume of empty space (pore space) in a material, usually expressed as a percentage, pores can become filled with water • Permeability – the degree to which a material allows fluids to pass through it via an interconnected network of pores and spaces Perched Aquifer: a mound of groundwater becomes trapped above a localized aquitard that lies above the regional water table Groundwater Flow: • Gravity and pressure cause groundwater to flow; groundwater can flow sideways and even upward Groundwater Flow: • Very slow compared to surface water • Rate can vary from 4 to 500 meters per year (13 to 1640 feet per year) • Rate is a function the slope of the water table (hydraulic head) and the permeability of the material through which the groundwater is flowing • Moves at a snail’s pace Artesian Well: • A well in which water rises on its own • Potentiometric surface – the elevation to which water in an artesian system would rise . O, 13. L, 14. N, 15. H Answers: 1. G, 2. M, 3. J, 4. B, 5. D, 6. K, 7. E, 8. I, 9. C, 10. A, 11. F, 12 GEO 101-007 10/28/15 if unimpeded; where there are flowing artesian wells, the potentiometric surface lies above ground Spring: • A natural outlet from which groundwater flows onto the ground surface • Where the ground surface intersects the water table n a discharge area Various Types of springs: • Where flowing groundwater collides with a steep, impermeable barrier, and pressure pushes it up to the ground along the barrier • Where a perched water table intersects the surface of a hill • Where downward-percolating water runs into a relatively impermeable layer and migrates along the top surface of the layer to a hillslope • Where a network of interconnected fractures channels groundwater to the surface of a hill Hot Spring Rock deposits: • Travertine- a rock composed of crystalline calcium carbonate formed by chemical precipitation from groundwater that has seeped out at the ground surface Groundwater Concerns: • Change of groundwater flow direction • Saltwater intrusion • Ground subsidence o When intensive irrigation removes groundwater, pore space in an aquifer collapses. o As a result, the land surface sinks, leading to the formation of ground fissures and causing houses to crack Chapter 18: Amazing Ice: Glaciers and Ice Ages 1. ___I__ Glacier A. (Breaking off of chunks of ice) 2. __E___ Sublimation B. Sediment deposited at sea by melting 3. __F___ Melting C. A strip of till along the side margins of a glacier 4. ___A__ Calving D. Cobble to boulder size clasts of rock found within till or random places where the glacier was once flowing 5. ___J__ Moraine E. (Evaporation of ice into water vapor) 6. __C___ Lateral Moraine F. (Ice melts and liquid water flows away) GEO 101-007 10/28/15 7. __G___ Medial Moraine G. A strip of till in the interior of a glacier, parallel to the flow direction of the glacier, formed by the lateral moraines of two merging glaciers 8. ___H__ Till H. Unsorted sediment carried by ice, deposited beneath, at the side, or at the toe of a glacier 9. __D___ Erratics I. A river or sheet of ice that slowly flows across the land surface and lasts all year long (movement caused by gravity) 10. __B___ Glacial Marine J. A sediment pile composed of till (glacial sediment) deposited by a glacier 11. ___K__ Glacial outwash K. Till from the glacier toe that is transported (and sorted) by braided streams 12. __P___ Loess L. A pair of thin layers of glacial lake-bed sediment, one consisting of silt brought in during the spring floods and the other of clay deposited during the winter when the lake’s surface freezes over and the water is still 13. __M___ Glacial Lake Bed M. Fine grained sediments deposited in glacial lakes; varves are common (alternating thin layers of clay and silt) 14. __L___ Varve N. The process by which the surface of a continent rises back up after an overlying continental ice sheet melts away and the weight of the ice is removed (still happening today in some areas) 15. __R___ Kettle Hole O. A streamlined, elongated hill formed when a glacier overrides glacial till 16. __O___ Drumlin P. Silt and clay size sediment transported away from glacier’s toe and deposited some distance away from the glacier 17. __Q___ Glacial Subsidence Q. The sinking of the surface of a continent caused by the weight of an overlying glacial ice sheet GEO 101-007 10/28/15 18. __N___ Glacial Rebound R. A circular depression in the ground made when a block of ice calves off the toe of a glacier, becomes buried by till, and later melts Louis Agassiz: • Geologist from Switzerland • Proposed that places in Europe that had random rocks showing up must have been a result of a glacier dropping the rocks as it melted Glacial Erratic: • Erratic o A boulder or cobble that was picked up by a glacier and deposited hundreds of kilometers away from the outcrop from which it was detached Ice (frozen water) is a mineral (naturally occurring, inorganic solid, with a definite chemical composition and regular crystal structure Layers of Snowfall: • Layers of snowfall are very much like layers of loose sediment • With time and pressure (from snow above), snowflakes recrystallize into solid ice Snow to solid ice: • Loose snow • Granular snow • Firn • Fine-grained ice • Coarse-grained ice • Firn o Compacted granular ice (derived from snow) that forms where snow is deeply buried; if buried more deeply, firn turns into glacial ice Formation of Glaciers: • Three criteria for glacier formation 1) Local climate must be cold enough that winter snow does not melt entirely away during the summer 2) There must be sufficient snowfall for a large amount of snow to accumulate 3) Slope of the surface must be gentle enough that the snow does not slide away in avalanches Types of Glaciers: • Two categories of glaciers 1) Mountain (alpine) – shape controlled by topography of mountains – flow from high to low elevation I. Cirque II. Valley III. Ice caps IV. Piedmont N 18.Q, 17.O, 16.R, 15.L, 14.M, 13.P, 12.K, 11.B, 10.D, Answers: 1. I, 2. E, 3. F, 4. A, 5. J, 6. C, 7. G, 8. H, 9. GEO 101-007 10/28/15 2) Continental – vast ice sheets that cover thousands of square kilometers of continental crust – today the only exists in Antarctica and Greenland How exactly do glaciers move? • Plastic deformation 1) Only occurs below 60 m 2) Grains change shape very slowly as new grains form while old grains disappear • Basal sliding 1) Must be warm enough for water to build up at base of glacier 2) Water along base on glacier acts as a lubricant on which the glacier can move (water decreases friction) • The rate of ice movement varies with time and within the glacier (friction slows down movement where ice contacts rock/sediment) Crevasse Formation • A large crack that develops by brittle deformation in the top 60 m of a glacier Glaciers are similar to bank accounts: • Deposits = snowfall • Withdrawals =ablation • Zone of accumulation • Equilibrium line • Zone of ablation • Terminus (toe) • Ablation includes: o Sublimation (evaporation of ice into water vapor) o Melting (ice melts and liquid water flows away) o Calving (breaking off of chunks of ice) Icebergs: • Ice is grounded in shallow water, but floats in deep water Sea Ice (also contribute icebergs to ocean) • Ice formed by the freezing of the surface of the sea GEO 101-007 10/28/15 Plucking and Abrasion: • Plucking is chunks of bedrock being plucked out by the moving ice • Abrasion is chunks of rock that has already been plucked up into the glacier that move against the bedrock as the glacier moves and cause abrasions Pleistocene Epoch (~2.6 mya to 11,000 ya) • Laurentide Ice Sheet – an ice sheet that spread over northeastern Canada during the Pleistocene ice age(s) Glaciation (glacial period): • A portion of an ice age during which huge glaciers grew and covered substantial areas of the continents Interglacial – a period of time between two glaciations Holocene – a period of geologic time since the last ice glaciation
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