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18 Cards in this Set
- Front
- Back
What is the circulation of Earth's water supply between the hydrosphere, atmosphere, geosphere, and biosphere called? |
The hydrologic cycle |
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How does urbanization (e.g., paving) affect runoff and infiltration in a small, previously forested, drainage basin? |
Runoff increases and infiltration decreases. |
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Which of the following must result in a lower base level for river and streams? |
Sea level drops; land rises. |
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Many large rivers in the Colorado Plateau meander in deep, narrow canyons and have no floodplains. How could this happen? |
Streams flowing in meanders cut down as the plateau rose. |
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Which river has the largest discharge of any in the world? |
Amazon |
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What will happen when a dam and reservoir are constructed on a graded river? |
Deposition upstream from the dam; channel downcutting below |
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Rivers and streams are persistent features on Earth's surface. Of the list below, which river, in its present state, is probably the oldest? |
Amazon |
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What type of flood? Seasonal precipitation or spring snowmelt over many watersheds and drainage basins; Mississippi River system annually |
Regional Floods |
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What type of flood? Local rainstorms, sometimes after a forest fire, deluging streams, creating a wall of water that roars down a canyon, and taking everything in its path; Big Thompson Canyon flood in Colorado, 1976 |
Flash flood |
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What type of flood? Form "bottlenecks" in the channel; occur repeatedly in the Red River in North Dakota |
Ice-jam floods |
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What type of flood? Failure of human structures function; Johnstown Flood in Pennsylvania in 1889 |
Dam-failure floods |
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What is a braided channel, and what is happening there? |
Wide and shallow stream, usually at the ends of glaciers; is choked with sediment, where there is not much "downhill" |
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What is the difference between a bar and a point bar? |
A bar is a small-scale channel deposit, sometimes elongated, in the middle of a stream; a point bar is a deposit of sediment on the inside of a meander. Both are good places to find gold nuggets. |
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Which best describes the difference between a delta and an alluvial fan? |
A stream deposits sediments at its mouth in water in a delta; a stream deposits sediments along steep mountain slopes in an alluvial fan. |
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Which of the following best describes a water gap? |
A steep-walled notch cut through a tectonic structure, usually a ridge of tilted rock |
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Why has Niagara Falls lasted so long and cut its channel back 7 miles (11 kilometers)? |
The Lockport Dolostone is a resistant rock unit that covers a wide zone between Lake Erie and Lake Ontario, and the Niagara River has to erode the weak layers underneath before it can retreat upstream. |
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Which one of the following statements correctly describes how stream terraces can form? |
A temporary base level is eliminated; the stream cuts down upstream from the old temporary base level, and the former floodplain is left well above the present elevation of the stream. |
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Which of the following best describes the development of distributaries at the mouths of major rivers such as the Mississippi River? |
The main channel divides into several smaller channels, carrying water in varying paths to base level. |