EARTH WEATHERING AND EROSION

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EARTH
WEATHERING
AND
EROSION
WEATHERING AND EROSION
WEATHERING AND EROSION WEATHERING AND EROSION

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WEATHERING AND EROSION WEATHERING AND EROSION
WEATHERING AND EROSION WEATHERING
Process by which rocks are broken down due
to exposure to processes occurring at the
Earth’s surface
Caused by
• Water
• Waves
• Wind
• Gravity
• Glaciers

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TYPES OF WEATHERING
A. Mechanical Weathering also called Physical
weathering
–Rock is broken down into smaller pieces of
the same material
–(no change in composition)
B. Chemical Weathering
–The breakdown or decomposition of rock
that occurs when minerals are changed into
different substances
–(change in composition)
MECHANICAL / PHYSICAL WEATHERING
1. Frost (Ice) Wedging
Process in which water freezes in the cracks
of rock and wedges (pushes) it apart because
water expands when it freezes.
Occurs where there are frequent freezes and
thaws.
FROST WEDING
Frost / Ice Wedging can
cause Potholes to form
in pavement

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2. Abrasion
The wearing away of rock material by
grinding action
Caused by sediment in Wind, Water, and
Glaciers
MECHANICAL / PHYSICAL WEATHERING  Wind abrasion sandblasting effect on stationary
rocks; (Arches National Park)
Hydraulic abrasion- water & sediments flowing
over boulders 3. Plants and Animals
Plant roots can split rock
Also known as: “Root pry”
or “Root action”
Animals dig holes, breaks
up rocks
MECHANICAL / PHYSICAL WEATHERING

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MECHANICAL / PHYSICAL WEATHERING
Tree growing
out of rock,
Tree roots also
break up
sidewalks
MECHANICAL / PHYSICAL WEATHERING
Exfoliation- gradual peeling of layers due to
uplift and frost action, typical of granite domes
EXFOLIATION OF IGNEOUS ROCK CHEMIICAL WEATHERING
 Chemical Weathering
–The breakdown or decomposition of rock that
occurs when minerals are changed into
different substances
–(change in composition)
–Involves Water, water vapor, Acids, and/or
Oxygen
O2

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CHEMIICAL WEATHERING
1. Hydrolysis
Carbonic Acid in water
dissolves Calcite. This
chemical weathering
can hollow out
underground Caverns
Limestone and Dolomite
both dissolve because they contain Calcite
CHEMIICAL WEATHERING
2. Oxidation
Oxidation of minerals
with iron (magnetite,
pyrite) results in the
formation of rust or
iron oxide.
This is why Mars is
the red planet
Copper turns rocks
green
RATE OF WEATHERING
How fast a rock weathers depends on 3 factors:
–Surface area
–Rock composition
–Climate
RATE OF WEATHERING
Surface area
–The greater the surface area, the faster the
weathering rate
–There are more surfaces to be weathered

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Rock Composition
–Some minerals are more
resistant than others
–For example, quartz is more
resistant (harder) than calcite
RATE OF WEATHERING RATE OF WEATHERING
Climate
(long term pattern of moisture and temperature)
–Weathering rates are faster in warm, wet
climates
 The removal and transport of weathered
materials by natural
agents such as
 Caused by
1. Glaciers
2. Running water
3. Gravity
4. Wind
5. Waves
EROSION
Mass of compacted ice and snow that
moves under its own weight
GLACIERS

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Friction at the base of the glacier is reduced by a
thin film of melt water.
Glaciers account for about 75% of the fresh
water on Earth
GLACIERS Glaciers can leave behind large boulders that are
known as an erratic
Drift or Till - all sediment that is deposited by
glacial activity
–Loess: fine powder, pulverized rock, that
blankets much of the northern mid-west
–Moraine: ridge or pile of boulders, gravel,
sand, and silt left at the end of a glacier
–Esker: type of outwash that accumulates in the
channels and tunnels of a glacier
GLACIAL DEPOSITS
GLACIAL DEPOSITS

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River stages
affect:
Velocity,
Gradient,
& discharge
which cause
Erosion
Massive Landslide
• The downward transportation of weathered
materials by gravity
EROSION-MASS MOVEMENT
EROSION-MASS MOVEMENT
• Mudflow/Earthflow
–Thick pastes of
sediments that travel
downhill at great
speeds
–Usually occur in dry
areas that get a large
quantity of rain all
at once
–Leaves a cone
shaped deposit
EROSION-MASS MOVEMENT

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Wind moves sand
dunes at the beach
and in the deserts.
WIND AND WAVES Deposition: The process of dropping or depositing
soil and sediments.
THANK YOU
QUESTION ANSWERS