Weathering

Mass Wasting

Erosion

Are all called external processes because?

The occur at or near Earth's Surface

The work of gravity:

Mass Wasting

Removal of vegetation

Root system bind soil and regolith (The layer of loose rock resting on bedrock) together

Gradiant or slope

Channel characteristics including shape, size, and roughness

Profile is a smooth curve

Ultimate (sea level)

Local or temporary

Raising base level cause deposition

Lowering base level cause eroision

 Abrasion?

Dissolution?

Abrasion lifts loosely consolidated particles

Dissolution stronger currents lift particles more effectively

Dissolved load

Suspended load

Bed load

Competence is reduced

Sediments begins to drop out

Stream sediments generally well sorted

Stream sediments are usually known as alluvium

Results from a sudden decrease in velocity

Narrow valleys

V-shaped

downcutting toward base level

Features often include rapids and waterfalls

Wide valleys

Stream is near base level

Downward erosion is less dominant

Stream energy is directed from side to side forming a floodplain

Erosion and deposition along a meandering stream

Land area that contributes water to the stream is the drainage basin

Imaginery line seperating one basin from another is called the divide

Common drainage patters include

dendritic

radial

rectangular

Trellis

irregularly branching tributary stream (treelike)

forms when underlying material is uniform

pattern is determined by the slope of the land; not material overwhich it flows

Streams spread out from a centeral area (spokes of found on dome like a wheel)

found on isolated volcanic cones

found on dome like hills or mountains

Pattern where tributaries are nearly parallel to one another

forms where there are underlying layers of alternating bands of resistant and less resistant rock

sinkholes

caverns

water is 6-9 c warmer than the mean air temperature of the locality

heated by cooling of igenous rock

intermittent hot springs

water turns to steam and erupts

water beneath the surface

water in the well rises higher than the initial groundwater level

Groundwater is often mildly acidic

contains weak carbonic acid

Dissolves calcite in limestone

Formed by dissolving rock beneath earth's surface

formed in zone of saturation

Composed of dripstone

Calcite deposited as dripping water

Common features include stalactites (hanging from the ceiling) and stalagmites (growing upward from the floor)

Formed by dissolving rock at, or near Earth's Surface

Common features:

sinkholes- surface depressions

sinkholes form by disolving bedrock and cavern collapse