geology test 3, chapter 11

Erosion

Erosion

the process by which the Earth's surface gets worn down by natural forces such as water, wind, and ice. These agents shape the land by wearing away the land surface, breaking down rocks into smaller pieces, and carrying those pieces away.

Saltation

the bouncing of particles along a stream bottom or desert floor

Traction

a force that contributes to the movement of particles situated on a stream bed or desert floor

Hydrologic Cycle:

also known as the water cycle, describes the continuous movement of water on, above, and below the surface of the Earth.

Evapotranspiration:

A combination of evaporation and transpiration from plants, which is a measure of water entering the atmosphere.

Precipitation

The act of a solid coming out of solution, typically resulting from a drop in temperature or a decrease of the dissolving material.

Infiltration

Water that works its way down into the subsurface

In which reservoir does most freshwater reside?

Freshwater reservoirs include lakes, rivers, wetlands, groundwater, and the atmosphere. Most freshwater (about 68.7%) resides in groundwater

Youthful streams

a stream that is actively down-cutting its valley in an area that has recently been uplifted

Step-pool

a characteristic of stream flow in which water flows from one pool to another, typically on a stream with a steep gradient

Braided

a stream pattern which is characterized by abundant sediment and numerous intertwining channels around bars

Meandering

the sinuous path taken by a stream within a wide flat flood plain

Dendritic patterns

resemble the branching structure of a tree, with smaller tributaries joining larger rivers

Radial patterns

have streams flowing outward from a central point, like spokes on a wheel.

Gradient from the headwaters to the mouth

The gradient, or slope, of a stream or river generally decreases from the headwaters (source) to the mouth (end).

V-shaped valleys

These streams or rivers have a steep gradient and cut deep into the landscape, creating a V-shaped valley.

Bed load

the fraction of a stream's sediment load that typically rests on the bottom and is moved by saltation and traction

suspended load

smaller particles that are carried in the water column

Oxbow

a part of a stream meander that has become isolated from the rest of the stream as the result of a meander cutoff

point bar

A deposit of sediment on the inside of a meander bend.

cut bank

The steep, eroding bank on the outside of a meander bend

The cross-sectional

profile of a meandering stream is broad and shallow, with a wide floodplain.

Permanent streams

flow year-round, while ephemeral streams flow only during and immediately after rainfall or snowmelt.

Alluvium

A deposit of sediment left behind by a stream or river

Discharge

the volume of water flow in a stream expressed in terms of volume per unit time (e.g., m3/s)

Undercutting

The process by which erosion undermines the banks of a stream or river, causing them to collapse

drainage basin

The area within a topographic basin or drainage divide in which water collects.

Tributary

A natural water stream that flows into a larger river or other body of water.

Mouth

The end of a river out of which water flows into a sea or other large body of water

closed basin

An internally draining watershed, whose waters do not flow to the ocean.

Drainage divide

The boundary between two river basins, where water flows in opposite directions.

Extent of the Mississippi river basin

The Mississippi river basin covers approximately 40% of the contiguous United States, encompassing 31 states and 2 Canadian provinces.