GEOG 1114: FINAL EXAM
121 Cards in this Set
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overland flow
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The general movement of unchanneled surface water down the slope of the land surface
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streamflow
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channeled movement of water along a valley bottom
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Overland vs Streamflow
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Overland is unchanneled, Streamflow is channeled
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valley
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That portion of the total terrain in which a stream drainage system is clearly established
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interfluve
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The higher land or ridge above the valley sides that separates adjacent valleys; drained by overland flow
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Drainage Basin & other name?
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An area that contributes overland flow and groundwater to a specific stream (Watershed or Catchment Basin)
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stream order
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system of stream hierarchy
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4 types of overland flow erosion
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Splash, Sheet, Rill & Gully
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splash erosion
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collision of raindrops with the ground, causing a blast of fine soil particles upward and outward, shifting them a few millimeters laterally
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sheet erosion
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water flows across the surface as a thin sheet, transporting material already loosened by splash erosion
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rill erosion
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a more concentrated flow picks upadditional material and scores the slope with numerous parallel seams or rills
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gully erosion
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if the process continues, the rills begin to coalesce into fewer and larger channels or gullies
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methods of erosion by streamflow? (4)
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transportation, competence, capacity, deposition
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transportation erosion
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Any water moving downslope, whether moving as overland flow or as stream flow, can transport rock material. Eventually, most of this material reaches the streams in the valley bottoms, where it is added to the stream- eroded debris and materials contributed by mass wasting to constitute t…
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competence erosion
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A measure of the particle size a stream can transport, expressed by the diameter of the largest particles that can be moved. It depends mainly on flow speed, with the power of the water generally increasing by the square of its speed.
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capacity erosion
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A measure of the amount of solid material a stream has the potential to transport, normally expressed as the volume of material passing a given point in the stream channel during a given time interval. It can vary tremendously over time, depending mostly on fluctuations in volume and flow…
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deposition erosion
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Whatever is picked up must eventually be set down, which means that erosion is inevitably followed by deposition. Overland or stream flow carries its load downslope or downvalley toward an ultimate destination (ocean, lake, or interior drainage basin).
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How does flow speed relate to erosion?
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Speed of the water will speed up erosion
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How do you increase flow speed?
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Gravity and the presence of clay (very slippery) can increase it
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3 pieces of stream load
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dissolved load, suspended load, bedload
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dissolved load
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some minerals, mainly salts, are dissolved in the water and carried in solution
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suspended load
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very fine particles of clay and silt are carried in suspension, moving along with the water without ever touching the streambed.
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bedload
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consists of sand, gravel and larger rock fragments; normally moved spasmodically, especially during floods (debris is transported some distance, dropped, and then picked up later and carried further)
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alluvium
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Any stream- deposited sedimentary material
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stream discharge & units
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a. the product of its velocity (V - length of travel per unit of time such as feet/second) times depth of the water (D - unit of length) times width (W of the water - units of length)
b. units of feet3/sec or cubic feet per second (cfs)
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recurrence interval
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The probability of a given-size flood occurring in a year; also called the return period
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consequent stream
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course is a direct consequence of the original slope of the surface upon which it developed, i.e., streams that follow slope of the land over which they originally formed.
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subsequent stream
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A stream that follows a line of geologic weakness, such as the outcrop of a soft bed, a sequence of major joints, a fault trace, or the axis of an anticline.
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antecedent stream
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maintains its original course and pattern despite the changes in underlying rock topography
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superimposed stream
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kept its course through the different preexisting lithologies andstructures encountered as it eroded downward into the underlying rock
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drainage patterns
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dentritic, parallel, trellis, rectangular, angular, contorted
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downcutting
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action of stream to erode a deeper channel; occurs when stream is flowing swiftly and/or flowing down a steep slope
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base level
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imaginary surface extending underneath the continents from sea level at the coasts and indicating the lowest level to which land can be eroded
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graded stream
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over a period of years, slope is delicately adjusted to provide, with available discharge and the prevailing channel characteristics
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knickpoint
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a sharp irregularity (such as a waterfall, rapid or cascade) in a stream- channel profile
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knickpoint migration
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upstream shift in location of a knickpoint due to erosion
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cut bank
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the outside bank of a water channel (stream), which is continually undergoing erosion.
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point bar
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depositional feature made of alluvium that accumulates on the inside bend of streams and rivers below the slip-off slope.
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How does headward erosion work to lengthen a stream
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a. Headward erosion: cuts into the interfluve at the upper end of a gully or valley
b. The part that is cut extends the stream a little bit until it adds up to lengthen
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What is the process of stream capture? What is the other name for it?
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a. Stream Piracy
b. An event where a portion of the flow of one stream is diverted into that of another by natural processes
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How/why does a delta form?
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Produced by the sudden reduction of a stream's velocity and the resulting deposition of the stream's load
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What is the largest delta in the United States?
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Mississippi River Delta
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floodplain
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A flattish valley floor covered with stream- deposited sediments (alluvium) and subject to periodic or episodic inundation by overflow from the stream
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3 theories of landform development
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Davisian, Penck, Equilibrium
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davisian theory
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He, under the concept of 'complete cycle of river life', postulated the cycle concept of progressive development of erosional stream valleys, and through the 'geographical cycle' described the sequential development of landforms through time.
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penck theory
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the characteristics of landforms of a given region are related to the tectonic activity of that region
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equilibrium theory
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Much variation in bedrock, regolith, soil around the earth: some soft, some hard
Crustal movement (vertical, horizontal) also varies: excessive uplift, minimal uplift
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exotic stream + ex
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a stream that flows into a dry region, bringing its water from somewhere else
Ex: Nile River
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ephemeral stream
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A stream that carries water only during the "wet season" or during and immediately after rain
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playa
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Dry lake bed in a basin of interior drainage
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salina
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Dry lake bed that contains an unusually heavy concentration of salt in the lake bed sediment
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salina lake + ex
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a. Salt lake; commonly caused by interior stream drainage in an arid environment
b. Ex: Utah's great salt lakes
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deflation
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the shifting of loose particles by wind blowing them into the air or rolling them along the ground
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abrasion
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the process of scraping or wearing down by friction
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sand dune
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a mound, ridge, or low hill or loose, windblown sand
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fossil dune
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Vast deposits of sandstone exhibit the characteristic "cross-bedding" of wind deposited sand, rather than the more typical horizontal strata of sediments accumulated in bodies of water
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desert varnish
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a dark shiny coating of iron and manganese oxides that forms on rock surfaces exposed to desert air for a long time
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desert pavement + other name
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(desert armor): hard and relatively impermeable desert surface of tightly packed small rocks
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What are the main features of a basin-and-range landscape?
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Largely without external drainage , with only a few exotic rivers flowing through or out of the region; consists of numerous fault block mountain ranges surrounding a series of interior drainage basins, including many down dropped grabens and down tilted half grabens
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What features do you find in the Piedmont Zone?
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transition area from the steep slopes of the ranges to the near flatness of the basins. Covered with several meters of unconsolidated sediment because it is an area of fluvial deposition.
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What type of landscape is Death Valley?
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Basin- and- range terrain
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Which mountains create the rain shadow that causes Death Valley to be so dry?
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Amargosa Range
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What features are you likely to find on a mesa-and-scarp terrain?
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Horizontal sedimentary strata, abrupt changes in slope angle,limestone & sandstone, irregular stair step pattern
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escarpment
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the hard layer protects underlying strata
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desertification + causes
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type of land degradation in which a relatively dry land region becomes increasingly arid, typically losing its bodies of water as well as vegetation and wildlife. It is caused by a variety of factors, such as climate change and human activities.
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snowball earth- what, when, cause & ending?
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A. Snowball earth is when almost the entire planet was covered in ice/snow.
B. Ended ~635 million ybp
C. Drop in insolation + GHG
D. Volcanic Activity
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types of mountain glaciers
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valley, alpine, and cirque glaciers
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types of continental glaciers
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Antarctica and Greenland
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Pleistocene Glaciation: How many glacial periods were there? When was it? What was the glacial period called that ended it? Where did the ice originate? How much of the land was ice-covered at the max extent? What were the indirect effects? What caused it?
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A. Max extent was 1/3 of land
B. 18 or 19 total glacial periods
C. 2.5 million to 10k ybp
D. Wisconsin glaciation ended it
E. Ice originated in subpolar + midlatitude regions
F. Max extent was 1/3 of land
G. Indirect effects- periglacial zone, sea level change, crustal depression
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2 main ice sheets associated with contemporary glaciation?
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Greenland and Antarctica
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What is happening with Antarctica? What is causing the majority of the melt? Where is most of the melt occurring?
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A. Antarctica is melting
B. Caused by warmer ocean currents
C. Below the ice
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How do glaciers and glacial ice form?
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Glaciers form when there is a net year to year accumulation of snow
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accumulation (glaciers)
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addition of ice by incorporation of snow
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ablation (glaciers)
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wastage of ice through melting and sublimation
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equilibrium (glaciers)
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equal addition and wastage of ice
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What are different types of glacial movement?
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Plastic Flow & Basal Slip
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What is the difference between flow and advance?
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Flow always occurs in glaciers, while advance means it is growing
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What are the ways glaciers erode the landscape?
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Glacial plucking, abrasion, subglacial meltwater erosion
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How do glaciers transport material?
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By picking it up from underneath or capturing material that falls on it
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What are the types of glacial deposition?
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Direct deposition by glacial ice, secondary deposition by meltwater
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How do continental ice sheets erode the landscape?
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Roche Moutonnée- a characteristic glacial landform produced when a bedrock hill or knob is overridden by moving ice
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What are the depositional features associated with continental ice sheets?
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moraines, kettle, drumlins
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moraines
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produced by glacial deposition of till, which consists of irregular rolling topography
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kettle
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irregular depression left large blocks of ice that are left from a retreating glacier
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drumlins
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a low, elongated hill formed by ice sheet deposition and erosion
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Describe the glaciofluvial features associated with continental ice sheets?
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A. Outwash Plain- extensive glaciofluvial feature that is a relatively smooth, flattish alluvial apron
B. Esker- long, sinuous ridge of stratified glacial drift composed largely of glaciofluvial gravel
C. Kame- steep mounds or conical hills of stratified drift
D. Lakes- water left behi…
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Describe all the ways mountain glaciers cause erosion?
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A. Cirque- a broad amphitheater hollowed out at the head of a glacial valley by glacial erosion and frost wedging
B. Arêtes and Cols- Narrow, jagged, serrated spine of rock
C. Horn- a steep-sided, pyramidal rock pinnacle
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What are the types of depositional features associated with mountain glaciers?
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Periglacial- occurring or operating adjacent to the margin of a glacier
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periglacial
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occurring or operating adjacent to the margin of a glacier
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What is patterned ground and how does it form?
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Polygonal patterns in the ground that develop in areas of seasonally frozen soil and permafrost
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What is a proglacial lake and how does one form?
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a lake formed when ice flows across or against the general slope of the land and the natural drainage is impeded or completely blocked so that meltwater from the ice becomes impounded against the ice front
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What are the Washington Scablands? What type of environment is this an example of? How did they form?
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A. Land formed when a large glacial lake drained
B. Proglacial lake
C. Formed when glaciers deposited ice
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What are the different types of wave motion?
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Oscillation, translation, refraction, erosion, tsunami
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wave refraction
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phenomenon whereby waves change their directional trend as they approach a shoreline; resulting in ocean waves breaking parallel with the shoreline
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How do waves erode the coastline?
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Gradually picking up and moving sediment
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tsunami + how they move & form
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very long wavelength oceanic wave generated by submarine earthquake, landslide, or volcanic eruption
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eustatic sea-level change
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change in sea level due to an increase or decrease in the amount of water in the world ocean
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How do organic secretions and stream flow help shape the shorelines?
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Organic secretions help create coral reefs; stream flow helps build shorelines b/c streams bring sediment from upriver
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longshore current
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currents that move water and sediment along the shore
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beach drift
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the zigzag movement of sediment caused by waves washing particles onto a beach at a slight angle; moves everything in a downwind direction
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What are the components of a beach profile?
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backshore, foreshore, nearshore, offshore
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backshore
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upper part of the beach, landward of the high-water line
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foreshore
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zone regularly covered by the rise and fall of tides
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nearshore
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extends from the low-tide mark, seaward to where the low-tide breakers begin to form - not exposed to the atmosphere
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offshore
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permanently underwater and deep enough that wave action rarely influences bottom
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spits
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linear deposits of marine sediment that is attached to the land at one or both ends
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baymouth bar
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a spit that extends entirely across the mouth of a bay, transforming the bay into a lagoon
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tombolo
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spit formed by sand deposition that connects an island to the mainland
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barrier island
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narrow offshore island composed of sediment; generally oriented parallel to the shore
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What is the difference between a bay and a lagoon?
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Bays are open and lagoons are closed off
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ria shoreline
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an embayed coast with numerous estuaries; formed by the flooding of stream valleys by the sea
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What are the 3 different features discussed for coastal emergence?
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wave- cut cliffs, wave- cut platform, marine terraces
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wave- cut cliffs
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waves erode cliffs most at their base
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wave- cut platform
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gently sloping, wave-eroded bedrock platform that develops just below sea level
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marine terraces
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a platform formed by marine erosion that has been uplifted above sea level
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What are the 3 different types of coral reefs?
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fringing reef, barrier reef, atoll
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fringing reef
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a coral reef built out laterally from the shore, forming a broad bench that is only slightly below sea level, often with the tops of individual coral "heads" exposed to the open air at low tide
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barrier reef
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a prominent ridge of coral that roughly parallels the coastline but lies offshore, with a shallow lagoon between the reefs and the coast
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atoll
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coral reef in the general shape of a ring or partial ring that encloses a lagoon
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Where do you find coral reefs?
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Generally found on coasts between the tropics of Cancer and Capricorn
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What kind of conditions are required in order for coral reefs to grow and survive?
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Shallow tropical waters, stable foundation, salt water
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GEOG 1114: MIDTERM