Erosion and Weathering
The process of making
sedimentary rocks
What is erosion?
• The mechanical
process of wearing or
grinding something
down
• The wearing away of
the earth’s surface
by natural
processes
• Corrosion: erosion by
chemical action
Types of Erosion
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•
•
•
Water
Wind
Glacier
Gravity
Water
• Occurs from chemicals in
the water and the force/flow
of water
• Chemicals break down
certain rocks like limestone
or chalk
• Force of water creates
cracks and crevasses
– These get bigger and bigger as it
gets eroded, particles of the rock
get carried in the water and
further aid erosion
Ocean Erosion
• Salts and other chemicals
in the water erode coastal
rocks
• These are dragged out to
sea and deposited in
other areas
• Wave power creates
erosion. Also particles of
rock and sediment aid to
the erosion process
Wind
• The wind picks up smaller
particles of rock (pebbles
and sand)
• They can also hit
landforms and take
pieces off them: This
friction causes the break
up of landforms
• The wind then deposits
the sediments (usually in
layers)
Glacier Erosion
• What is a GLACIER?:
A huge mass of ice slowly flowing over a
land mass
• These large bodies of ice
pick up rocks and erode
the earth’s surface
• Powerful eroding
machine, picking up
pieces of rock the size of
houses in some places
• Glaciers are so powerful
they can carve valleys
and create landforms
Gravity Erosion
• Gravity can pull soil,
mud, and rocks down
cliffs and hillsides. This
is called mass
movement.
• Gravity also plays a
roil in the water
erosion such as runoff
down a mountation
Types of Gravity Erosion
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•
•
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Landslides
Mudslides
Slump
Creep
Soil Formation
• Small bits of eroded
material and decaying
matter build up over
time and can create soil
• The layers they formed
are named. The top
layer usually has the
most nutrients and is
most important for
farmers (topsoil)
Soil Erosion
• Biggest problem for
farmers
• Wind and rain remove
topsoil and nutrients
• Makes the soil infertile and
it breaks up leaving
crevices
Deposition
Definition
• Deposition- the process in which sediment
is laid down in new locations
– The end result of erosion
• Law of Superposition: Sedimentary layers
are deposited in a time sequence, with the
oldest on the bottom and the youngest on
the top
Water Deposition
• Alluvial fan- fan shaped deposit of
sediment on land
• Delta- sediment from a stream deposited
where a river enters a large body of water
Aluvial Fan
Delta
Glacial Deposition
• As a glacier melts, it creates landforms by
depositing its sediment load
– Till-unsorted mixture of sediment containing
fragments of various sizes
– Moraine-mounds of sediment at the downhill
end of the glacier and along its side
Till and Moraines
Wind Deposition
• Sand dunes- large deposits of sand
dropped from wind
– Sand dunes can move as the wind picks up
sand from the back of the dune and blows it to
the front
Sand Dunes
Arches National Park
Grand Canyon
All three rock types can be found here, igneous, metamorphic and sedimentary. They
were formed as a result of glaciation, tectonic action and river process.