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EROSION

Ø  erosion – (destructive) process that wears down & carries away rock & soil

Ø  Erosion acts through

Ø weathering

Ø force of gravity

Ø movement of streams, groundwater, glaciers, wind, and waves

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EROSION

Ø  erosion acts through weathering, force of gravity, & through movement of streams, groundwater, glaciers, wind, & waves

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WEATHERING

Ø  weathering – process by which rocks are chemically altered or physically broken down into fragments at or near Earth’s surface

Ø  2 forms

Ø mechanical - process of physically breaking rock into smaller fragments

Ø chemical – process in which rock is broken down by chemical reactions

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WEATHERING

Ø  mechanical weathering - process of physically breaking rock into smaller fragments

Ø abrasion – occurs when rocks scrape or grind against each other

Ø  chemical weathering - process in which rock is broken down by chemical reactions

Ø e.g. rusting or when slightly acidic rain interacts with minerals in rock

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WEATHERING

Ø  Rate that it occurs depends on

Ø temperature

Ø availability of water

Ø type of rock Ø  chemical weathering tends to occur more rapidly in areas with

high temperature & abundant rainfall b/c speeds up chemical reactions

Ø  mechanical tends to occur more rapidly in regions that temp. conditions alternate between freezing & thawing

Ø  limestone & marble (contain calcite reacts with carbonic acid)

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MASS MOVEMENT

Ø  mass movement – downward movement of rock and soil due to gravity

Ø  i.e. landslides, mudflows, creep, slumping

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MASS MOVEMENT

Ø  landslides – rapid movement of large amounts of rock & soil Ø  occur after heavy rains or earthquakes on

steeper slopes

Ø  mudflows – rapid mass movement of soil & other sediment mixed with water Ø  occur where there is fine sediment has

collected in thick layers

Ø water loosens sediment & mixes increasing weight à washes down slope

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MASS MOVEMENT

Ø  creep – soil gradually moves down a slope Ø Usually occurs due to formation of ice; freezing

causes soil to expand outward & then when it thaws soil moves a small distance downhill

Ø  slumping – weak layers of soil or rock suddenly move downslope as a single unit Ø  gravity acting on water-saturated soil & rock

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MASS MOVEMENT