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| A form of mechanical weathering that occurs when loose fragments or particles of rocks and minerals that are being transported, as by water or air, collide with each other or scrape the surfaces of stationary rocks. |
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| A triangular deposit of sediment left by a stream that has lost velocity upon entering a broad, relatively flat valley. |
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| The lowest level to which a stream can erode the channel through which it flows, generally equal to the prevailing global sea level. |
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| A body of coarse particles that move along the bottom of a stream. |
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| The amount of water that can be carried by a stream or river. Depends on the width, the depth, and the steepness. |
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| A deposit of sediment that forms where a stream enters a standing body of water such as a lake or ocean. The name is derived from the Greek letter "delta" because these deposits typically have a triangular shape in map view. |
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| The volume of water in a flowing stream that passes a given location in a unit of time. Frequently expressed in cubic feet per second or cubic meters per second. Calculated by the formula Q = A x V where Q is the discharge, A is the cross sectional area of the channel and V is the average velocity of the stream. |
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| A ridge that separates two adjacent drainage basins. |
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drainage basin or watershed [image] |
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| The geographic area that contributes runoff to a stream. It can be outlined on a topographic map by tracing the points of highest elevation (usually ridge crests) between two adjacent stream valleys. Also referred to as a "watershed". |
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| a sudden and destructive rush of water down a narrow gully or over a sloping surface, caused by heavy rainfall. |
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| A flood plain is a level area on either side of a river or stream that is submerged at times of high water and where accumulations of silt and sand are deposited, away from the main channel. |
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A very small channel formed by running water. Gullies hold water for brief periods of time after a rain storm or snow melt. |
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| a fluvial process of erosion that lengthens a stream, a valley or a gully at its head and also enlarges its drainage basin. |
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| A long continuous ridge built by people along the banks of a stream to contain the water during times of high flow. Natural levees can also be built along the banks of a stream. When the flood water decelerates upon leaving the channel, sediments quickly drop out of suspension and build a ridge over time. |
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| A stream that traverses relatively flat land in fairly evenly spaced loops and separated from each other by narrow strips of floodplain. |
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| A crescent-shaped body of standing water formed from a single loop that was cut off from a meandering stream, typically by a flood that allowed the stream to flow through its floodplain and bypass the loop. |
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| A cylindrical or hemispherical hold in the bedrock of a stream that is formed from the continual swirling motion of sand and gravel by swirling currents. |
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| A chemical weathering process in which a material is dissolved. Also, the transport of dissolved ions by the water of a stream. |
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| A stream that has lost part of its drainage is termed beheaded. Stream piracy is also called stream capture or river capture. |
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| Transport of sediment by wind or water currents that are strong enough to keep the sediment particles continuously above the stream bottom or ground. (See traction and saltation for comparison.) |
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| a transverse gap in a mountain ridge, cut by and giving passage to a stream or river. |
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