Erosion and Deposition

TRUE OR FALSE: The Earth’s surface
has stayed the same for thousands of years
 FALSE: the Earth’s surface is always
changing

EROSION
 Is the process by which natural forces move
weathered rock and soil from one place to
another.
 Sediment – material moved by erosion .

DEPOSITION
 Occurs where the agents of erosion lay down
sediment.

Mass Movement
 Any one of several processes that move
sediment downhill.

Different types of Mass Movement
 Landslide
- occurs when rock and
soil slide quickly down a
steep slope.

 Mudflow
- mudflow is a rapid
downhill movement of a
mixture of water, rock,
and soil.

 Slump
- a mass of rock
and soil suddenly slips
down a slope.

 Creep
- very slow
downhill movement of
rock and soil.

Water Erosion
Runoff – all the remaining
water that moves the
Earth’s surface.

Rills and Gullies
 Rills
- tiny grooves in the
soil.
 Gully
- a large groove , or
channel, in the soil that
carries runoff after a
rainstorm

Streams and Rivers
 Stream
- a channel along
which water is
continually flowing
down a slope.
 River
- a large stream

Amount of Runoff
 In an area depends on five main factors:
 1st – amount of rain
 2nd – vegetation
 3rd – type of soil
 4th – shape of the land
 5th – how people use the land

Erosion by River
 Through erosion, a river creates a waterfalls,
flood plains, meanders, and oxbow lakes.

Waterfall
 May occur where a
river meets an area of
rock that is very hard
and erodes slowly.

Flood plain
 Flat, wide area of land
along a river.

Meander
 A loop like bend in the
course of the river

Oxbow lake
 A meander that has
been cut off from the
river.

Deposits by River
 Deposition creates landforms such as alluvial
fans and deltas. It can also add soil to a river’s
flood plain.

Alluvial Fans
 A wide, sloping
deposit of sediment
formed where a
stream leaves a
mountain range.

Deltas
 Sediment deposited
where a river flows into
an ocean or lake.

Groundwater Erosion
 Groundwater can cause
erosion through a process of
chemical weathering.
 Stalactite – hangs down from
the roof of a cave.
 Stalagmite – pointed piece of
rock that sticks u p from the
floor.

How Water Erode and Carries Sediment
 Most sediment washes or falls into the river as a
result of mass movement and runoff. Other
sediment erodes from the bottom or sides of the
river.
 Abrasion- is the wearing away of rock by grinding action.
- occurs when particles of sediment in flowing
water bumped into the steam again and again.

Erosion and Sediment Load
 A river’s slope, volume of flow, and the shape
of its trembled all affect how fast the river
flows and how much sediment it can erode.

Slope
 Is the amount the river drops toward sea level
over a give distance.

Volume of Flow
 A river’s flow is the volume of water that
moves past a point on the river on a given
time.

Streambed Shape
 Affects the amount of friction between the water
and the streambed.
 Friction – is the force that opposes the motion of one
surface as it moves another surface.
 Turbulence – water moves every which way in a
movement.

Glaciers
 Any large mass of ice that moves slowly over
land.
 There are 2 kinds of glaciers- valley and
continental glaciers.

Valley Glaciers
 A long, narrow glacier
that forms when snow
and ice build up high in
a mountain valley.

Continental Glacier
 That covers much of a
continent or large
island.

Glacial Erosion
 The movement of a glacier changes the land
beneath it.
 The 2 processes by which glaciers erode the land
are plucking and abrasion.

Plucking
 As a glacier flows over the land, it picks up
rock in a process.

Abrasion
 is the wearing away of rock by grinding
action.

Glacial Deposition
 When a glacier melts, it deposits the sediment it
eroded from the land, creating various
landforms.
 Till- mixture of sediments that a glacier deposits
directly on the surface.
 Moraine- is the ridge of till at the farthest point
reached by a glacier.

Waves
 HowWaves Form
the energy in waves come from wind that
blows across the waters surface.
 Erosion byWaves
Large waves hit rocks along the shore with
a great force.

Waves
 Deposits byWaves
waves shape the coast through both erosion
and deposition.
o Beach - Is an area of wave washed sediment along a
coast.
o Longshore drift – repeated waves hit the beach ,
some of the beach

Waves
o Longshore drift – repeated waves hit the
beach , some of the beach sediment moves
down the beach with the current.
o Spit – is a beach that projects like a finger out
into the water.

Wind
 HowWind Causes Erosion
the main way that wind causes erosion is
by deflation.
 Deflation – process by which wind removes
surface materials.

 Deposits Resulting fromWind Erosion
wind erosion and deposition may form sand
dunes and loess deposits.
 Sand dunes – a deposit of windblown sand.
 Loess – fine, wind deposit sediment.

Better to fail with
honor than succeed by
fraud.
- Sophocles

1-3. give at least 3 different types of mass
movement.
4. Is the process by which natural forces move
weathered rock and soil from one place to
another.
5. Is the wearing away of rock by a grinding
action.

6-7.What are the 2 kinds of glacier?
8. Deposit of windblown sand.
9. An area of wave-washed sediment along a
coast.
10. Fine, wind- deposited sediment.

Key Answers
1-3 .Landslides, mudflows, slump, creep
4. Erosion
5. Abrasion
6-7. continental and valley glacier
8. Sand dune
9. Beach
10. Loess

Reference
 http://www.slideshare.net/lovenaces60/weathering-and-erosion-
4851461?qid=5fe4fa68-57b4-4805-805a-
12c731c3137d&v=default&b=&from_search=12

Erosion and Deposition

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