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Transcript
Erosion & Deposition
Erosion
• the process by which natural
forces move weathered rock and
soil from one place to another
Causes of Erosion
• Gravity
• Running water
• Wind
• Glaciers
Causes of Erosion
• Gravity = force that moves rock and
other materials downhill
– Mass movement—process of moving
sediment downhill
– May be fast or slow
Causes of Erosion
• Gravity
– Force that moves rock and other
materials downhill
– Mass movement—process of
moving sediment downhill
– May be fast or slow
– Types of mass movement:
• Landslides—rock & soil
slide quickly down a steep
slope
Causes of Erosion
• Gravity
– Force that moves rock and other
materials downhill
– Mass movement—process of
moving sediment downhill
– May be fast or slow
– Types of mass movement:
• Mudflows—rapid downhill
movement of a mixture of
water, rock, and soil
Causes of Erosion
• Gravity
– Force that moves rock and other materials downhill
– Mass movement—process of moving sediment downhill
– May be fast or slow
– Types of mass movement:
• Slump—one large mass of
rock and soil suddenly slips
down a slope
Causes of Erosion
• Gravity
– Force that moves rock and other materials downhill
– Mass movement—process of moving sediment downhill
– May be fast or slow
– Types of mass movement:
• Creep—very slow downhill
movement of rock and soil
Causes of Erosion
• Running Water = #1 agent of erosion
Causes of Erosion
• Running Water
– #1 agent of erosion
– Types of running water:
• Streams
– Small streams = creeks
– Large streams = rivers
Colorado River
Grand Canyon
Causes of Erosion
• Running Water
– #1 agent of erosion
– Types of running
water:
• Streams
• Waves
Causes of Erosion
• Wind = Blows sediment
Sand dunes
Dust Bowl
Causes of Erosion
• Glaciers = Large masses of moving ice
– Movement
changes the land
beneath them
Alaska
Deposition
• the natural process of laying down
sediments in a new location
– creates new
landforms
Deposition
• the natural process of laying down sediments
in a new location
– creates new
landforms:
• Oxbow lake—
deposition
blocks off
part of a river
Deposition
• the natural process of laying down sediments
in a new location
– creates new
landforms:
• Delta—
sediment is
deposited at
the end of a
river
Deposition
• deposited sediments are laid down in
layers
• layers of sediment
are compacted under
pressure and eventually
form sedimentary rock
Deposition
• deposited sediments are laid down in layers
• Layers of sediment are compacted under pressure and
eventually form sedimentary rock
Sedimentary rocks
are like ogres and
onions…they have
layers.
Deposition
• deposited sediments are laid down in layers
• Layers of sediment are compacted under
pressure and eventually form sedimentary
rock
Most fossils are found in
sedimentary rocks because
organisms get covered and
preserved by the layers
then mineral replacement
occurs over time.
Weathering, erosion and deposition
are all part of a never-ending cycle that
constantly shapes and reshapes the
land.
Weathering, erosion and deposition
are all part of a never-ending cycle that
constantly shapes and reshapes the
land.
Destructive forces—break down
Constructive forces—build up
Weathering, erosion and deposition are
all part of a never-ending cycle that
constantly shapes and reshapes the land.
Destructive
Forces
Destructive
Forces
Weathering
Erosion
Breaks down rock
Carries sediment away
Constructive
Forces
Deposition
Takes sediment to a new
location to build new rock layers