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Glossary
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Below you will find key words and concepts that you should remember from this chapter.
abrasion  The grinding away of rock by friction and impact during transportation.
(See page(s) 401)
alluvial fan  Large fan-shaped pile of sediment that usually forms where a stream’s velocity decreases as it emerges from a narrow canyon onto a flat plain at the foot of a mountain range.
(See page(s) 412)
bar  A ridge of sediment, usually sand or gravel, that has been deposited in the middle or along the banks of a stream by a decrease in stream velocity.
(See page(s) 403)
base level  A theoretical downward limit for stream erosion of Earth’s surface.
(See page(s) 419)
bed load  Heavy or large sediment particles in a stream that travel near or on the stream bed.
(See page(s) 402)
braided stream  A stream that flows in a network of many interconnected rivulets around numerous bars.
(See page(s) 406)
delta  A body of sediment deposited at the mouth of a river when the river velocity decreases as it flows into a standing body of water.
(See page(s) 409)
dendritic pattern  Drainage pattern of a river and its tributaries, which resembles the branches of a tree or veins in a leaf.
(See page(s) 397)
discharge  In a stream, the volume of water that flows past a given point in a unit of time.
(See page(s) 400)
dissolved load  The portion of the total sediment load in a stream that is carried in solution.
(See page(s) 402)
distributary  Small shifting river channel that carries water away from the main river channel and distributes it over a delta’s surface.
(See page(s) 409)
divide  Line dividing one drainage basin from another.
(See page(s) 396)
downcutting  A valley-deepening process caused by erosion of a stream bed.
(See page(s) 419)
drainage basin  Total area drained by a stream and its tributaries.
(See page(s) 396)
drainage pattern  The arrangement in map view of a river and its tributaries.
(See page(s) 397)
flood plain  A broad strip of land built up by sedimentation on either side of a stream channel.
(See page(s) 409)
graded stream  A single bed with coarse grains at the bottom of the bed and progressively finer grains toward the top of the bed.
(See page(s) 419)
headward erosion  The lengthening of a valley in an uphill direction above its original source by gullying, mass wasting, and sheet erosion.
(See page(s) 422)
hydraulic action  The ability of water to pick up and move rock and sediment.
(See page(s) 401)
hydrologic cycle  The movement of water and water vapor from the sea to the atmosphere, to the land, and back to the sea and atmosphere again.
(See page(s) 395)
incised meander  A meander that retains its sinuous curves as it cuts vertically downward below the level at which it originally formed.
(See page(s) 424)
lateral erosion  Erosion and undercutting of stream banks caused by a stream swinging from side to side across its valley floor.
(See page(s) 423)
meander  A pronounced sinuous curve along a stream’s course.
(See page(s) 407)
meander cutoff  A new, shorter channel across the narrow neck of a meander.
(See page(s) 407)
natural levee  Low ridges of flood-deposited sediment formed on either side of a stream channel, which thin away from the channel.
(See page(s) 409)
oxbow lake  A crescent-shaped lake occupying the abandoned channel of a stream meander that is isolated from the present channel by a meander cutoff and sedimentation.
(See page(s) 409)
point bar  A stream bar (see definition) deposited on the inside of a curve in the stream, where the water velocity is low.
(See page(s) 407)
pothole  Depression eroded into the hard rock of a stream bed by the abrasive action of the stream’s sediment load.
(See page(s) 401)
radial pattern  A drainage pattern in which streams diverge outward like spokes of a wheel.
(See page(s) 397)
rectangular pattern  A drainage pattern in which tributaries of a river change direction and join one another at right angles.
(See page(s) 397)
saltation  A mode of transport that carries sediment downcurrent in a series of short leaps or bounces.
(See page(s) 402)
sheetwash  Water flowing down a slope in a layer.
(See page(s) 396)
solution  Usually slow but effective process of weathering and erosion in which rocks are dissolved by water.
(See page(s) 401)
stream  A moving body of water, confined in a channel and running downhill under the influence of gravity.
(See page(s) 395)
stream channel  A long, narrow depression, shaped and more or less filled by a stream.
(See page(s) 396)
stream gradient  Downhill slope of a stream’s bed or the water surface, if the stream is very large.
(See page(s) 399)
stream terrace  Steplike landform found above a stream and its flood plain.
(See page(s) 423)
stream velocity  The speed at which water in a stream travels.
(See page(s) 398)
superposed stream  A river let down onto a buried geologic structure by erosion of overlying layers.
(See page(s) 424)
suspended load  Sediment in a stream that is light enough in weight to remain lifted indefinitely above the bottom by water turbulence.
(See page(s) 402)
traction  Movement by rolling, sliding, or dragging of sediment fragments along a stream bottom.
(See page(s) 402)
trellis pattern  A drainage pattern consisting of parallel main streams with short tributaries meeting them at right angles.
(See page(s) 397)
tributary  a small stream flowing into a larger one.
(See page(s) 396)







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