4 FACTORS THAT CAUSE EROSION: GRAVITY RUNNING WATER WIND GLACIERS

EROSION FROM GRAVITY **LANDSLIDES **MUDFLOWS **SLUMP **CREEP

LANDSLIDES Most destructive

MUDFLOWS (MUDSLIDES) Occurs after heavy rains Soil high in clay Soil is saturated

SLUMP 1 huge chunk of land moves down   SLUMP                                                                                              1 huge chunk of land moves down Occurs when water soaks the bottom of soil rich in clay

CREEP Very slow movement of soil Occurs after freezing and thawing of water beneath the surface

EROSION FROM RUNNING WATER SURFACE EROSION GROUND WATER WAVES

SURFACE WATER EROSION Run-off: Water that moves over Earth’s surface Amount depends on: Amt of rain Amt of vegetation Type of soil Steep or flat Use of land (parking lots, etc)

Types of Surface Water Erosion Rill: A small stream that forms during a heavy rain

GULLY Gully: a large groove or channel that forms during a heavy rain Rills join to form gullies Only has water during a heavy rain

STREAMS Streams: Rarely dry up Gullies join to form streams

RIVERS Rivers result when streams join together

TRIBUTARY: Streams & rivers that flow into a larger river

Rills join to form gullies; Gullies join to form streams; Streams join to form rivers.

Rills are tributaries for gullies; Gullies are tributaries for streams; Streams are tributaries for a river

GROUND WATER Water that doesn’t evaporate and soaks into the ground

GROUND WATER EROSION Ground water erosion is caused by chemical weathering Water soaks into the ground, combines with CO2, forms weak acid and dissolves limestone forming caves

EROSION BY WAVES Waves break down rock and transfer sand and sediments

Waves are produced by wind The size of a wave depends on: *How long the wind blows *How fast the wind How far the wind

Waves move energy from place to place but not water. Water molecules move in circles and end up where they started

Parts of a wave

As the wave nears shore, the friction slows the wave down As the wave nears shore, the friction slows the wave down. Wave length gets shorter, height gets higher, wave “falls over.” It is now a breaker.

Weakest kind of erosion EROSION CAUSED BY WIND Weakest kind of erosion

Wind caused this “deflation” which resulted in this hollow left behind from wind erosion

Model of wind erosion

All sediments are eventually deposited by falling to the ground

REVIEW There are 4 factors causing erosion: Gravity (landslides, mudflows, slump, creep) Running Water (surface erosion, ground water, waves) Wind Glaciers

Check your knowledge quiz: Landslide, mudflow, slump or creep?

Landslide, mudflow, slump or creep?

Landslide, mudflow, slump or creep?

Landslide, mudflow, slump or creep?

Rill, gully, stream or river?

Rill, gully, stream or river?

Rill, gully, stream or river?

Rill, gully, stream or river?

1. Caves are formed from _______________ 2. Waves are produced from _____________ Wave sizes are dependent on how______, how _____ & how ______ the wind blows. The weakest form of erosion is_______ Why do waves break? What are the parts to a wave? Waves move __________ but NOT _____