Erosion and Deposition PPT€¦ · released/dropped by their agent of erosion –Process of erosion...
Transcript of Erosion and Deposition PPT€¦ · released/dropped by their agent of erosion –Process of erosion...
Erosion
and
Deposition
Agents, Forces, and Results
What Caused This?
What is Erosion?
•Erosion – moving of rock material from one place to a new location
Weathering has to happen before erosion. The
rocks have to be broken into smaller sediments
before they can be eroded away.
Weathering & Erosion Study Jams
AGENTS OF EROSION
•Wind
•Flowing water
•Waves
•Gravity
•Moving Ice (glaciers)
What Is Wind Erosion?
• Wind – sediments that have been transported by wind appear pitted (holes) and frosted (glazed) – Effective in moving small, loose material
– Occurs in areas where there is not enough rainfall to support vegetation
– Main effects: 1. Wind causes small particles to be lifted and moved away.
2. Suspended particles may impact on solid objects causing erosion by abrasion (rubbing).
What Is Water Erosion?
• Flowing Water – sediments transported by water appear rounded and smooth
– Most influential force in erosion
– Transports large objects with fast moving streams
– Helps create landforms:
• rivers
• lakes
• oceans
What Is Wave Erosion?
• Waves – relentless pounding can throw broken rocks against the shore and wash away fine grains
• Erodes (transports):
• softer/weaker rock first
• harder/more resistant left behind
• Can create landforms based on where waves hit land and which rocks they transport
What Is Gravitational Erosion?
• Gravitational Erosion – downward movement of rock and sediments, mainly due to the force of gravity – Streams and glaciers
• move material from higher to lower elevation– Occurs continuously on all slopes
What Is Glacial Erosion?
• Glaciers– moving ice that carries rocks; appear
scratched and grooved
What is Deposition?
• Deposition – the process where sediments are released/dropped by their agent of erosion
– Process of erosion stops:• when the moving particles fall out of the transporting
medium and settle on a surface– Speed of the medium slows or the resistance of the
particles increases, the balance changes and causes deposition
– Speed can be reduced by large rocks, hills, vegetation, etc.
Deposition - Wind
Transportation of particles in wind:.
– Material is deposited when the wind changes direction or loses its
strength.
– Fine particles can be deposited hundreds of km from its original
source in the desert
– Heavier material may be blown along the ground
–Dunes: a mound that forms when particles suspended in the
wind hit an obstacle and stop
Deposition - Water
• SPEED
• As the speed of the water decreases, the water's ability to carry sediment also decreases.
• Deposited in streams, rivers, and oceans:
• Running water deposits sediments where the slowing water can no longer move them.
• Largest particles are deposited near the shore.
• Increasingly smaller particles settle out farther from the shore where the water is calmer.
DEPOSITION - ICE
• Glacial flows of ice – become slower when the ice begins melting
– Deposits left by glaciers:– look similar to normal river deposits and are called outwashes.
– Moraines are large chunks of broken rock left at the base and sides of the glacier as it melts and recedes.
– Finer material is carried in the rivers that form when the glacial ice melts.
What’s the Difference?
• WEATHERING – Think of weather wearing rock down.
• EROSION – Think of a road and traveling.
• DEPOSITION – Think of depositing money into a bank.