The Forces of Weathering and Erosion€¦ · • Floodplains. Water Deposition Deltas –slow river...
Transcript of The Forces of Weathering and Erosion€¦ · • Floodplains. Water Deposition Deltas –slow river...
Weathering
And
Erosion
Weathering
Types
And
Erosion
&
Deposition
Breaking it Down the Real Earth surface!How does Erosion and Deposition Change the Surface of the Earth?
S6E5 d. Tell steps that change rocks and the surface of the Earth.Learning Target: I can explain the Forces that Change the Face of Earth.
Essential Question(s): How does water and wind change the surface of the earth?
Directions: Read EACH slide then decide what information to record… (Some slides may be in red bold letters others underlined)
Weathering• Weathering is simply the chemical and/or
physical breakdown of a rock material--
weathering involves specific processes acting on
rock materials at or near the surface of the Earth
The Different Types of WeatheringThere are many different types of Physical /
mechanical weathering.
Here are a few AGENTS:
•Root Pry
• Exfoliation
• Frost Action
• Wind Abrasion
• Frost action
Root plant action Pry
The tree is growing in the rock and soon the rock will break apart because of the
tree roots.
This is a picture of the Half Dome. The
rock is peeling away from the
mountain in layers just like an onion. This is exfoliation.
Frost Action or ice wedging slowly breaks up this sedimentary rock into unusual shapes.
These rocks have been blasted by wind and sand causing them to become rounded.
WIND ABRASION
Chemical weathering
and AGENTS:
• Acids in Groundwater
• Karst Topography
Living Organisms
This rock is red because of the oxidation of iron in the sediment when the rock was being
formed.
Acid Rain
1908 to 1969
Acid rain has eaten away this limestone statue.
Karst Topography
• A type of landscape in rainy regions where
there is limestone near the surface,
characterized by caves, sinkholes, and
disappearing streams.
• Created by chemical weathering of
limestone
Features of Karst: Sinkholes
Features of Karst: Caves
Living Organisms
• Lichens that grow on rocks produce weak
acids that chemically weather rock
Chemical
Weathering
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2. Particle Size – Larger particles weather slower and smaller
particles weather at a faster rate.
There are 4 factors that affect the rate of weathering:
1. Surface Area (exposure) - Exposing more surface area will
increase the rate of weathering.
3. Chemical Composition (what a rock is made of) – Certain rocks
and minerals are naturally weaker than others, while others are more
resistant (stronger).
4. Climate – Warmer, moister climates have the most weathering.
Heat & Water speed up all chemical reactions. This is the most
important factor in weathering.
Erosion is the process by which soil and rock are moved from one location to another on the surface by natural processes such as wind or water flow, and then transported and deposited in other locations.
Erosion
There are many kinds of Erosion.
Here are a few AGENTS:
• Wave Action
• Running Water
• Landslides
• Avalanche
•Glaciers
• Slump
•Creep
• Rock Fall
• Mud Flow
What is Erosion? Erosion is defined as removal of rocks
and soil by wind, water, ice and gravity.
Wind, water, ice and gravity are also
known as the agents of erosion and
through erosion, a river creates valleys,
waterfalls, flood plains, meanders, and
oxbow lakes
Water Erosion
Water running downhill is the major agent of
erosion that has shaped Earth's land surface.
The force of a falling raindrop can loosen and
pick up soil particles. As water moves over
land, it carries these particles with it. This
moving water is called runoff, which is water
that moves over Earth's surface.
Wave action is when waves hit the rocks and pieces of rock break off.
In this picture the running water eroded the sides of this canyon and created the V-shaped valleys.
Gravity Erosion-Rock Fall
Gravity Erosion is better known as Mass Movement and
is defined as the transfer of rock and soil down slope by
direct action of gravity without a flowing medium (such
as water or ice). Some of the best examples of Mass
Movement are:
Creep
Rock fall Slump
Landslides Avalanches
Mass Movements
• Landslides, mudslides, slump and creep
landslide clip.mpeg
Slower Faster
This is a picture of a landslide. A type of mass wasting.
In this picture the land has slumped
into the road below.
This is a diagram of creep. The hillside slowly slips over many years from
temperature or water.
This is a picture of an avalanche. It is similar to a landslide with ice and
snow instead of rock.
What type of mass movement is each picture?http://classes.colgate.edu/dkeller/geol101/massw/mass.htm
LANDSLIDE MUDFLOW
SLUMP CREEP
1 2
3 4
Ice Erosion
Glaciers wear down the landscape; by picking up and
carrying debris that moves across the land along with
the ice.
Glaciers can pick up and carry sediment that ranges
in size from sand grains to boulders bigger than houses.
Moving like a conveyor belt or a bulldozer, a single
glacier can move millions of tons of material!
How much erosion takes place is determined by the:
•**Sum (Glaciers are massive!)
•Slope
•Speed
•Surface
IceIce (glaciers) carry sediment.
This is a picture of a glacier which carves out a U-shaped valley where it flows dragging
rocks and boulders along the way.
Mrs. Degl 34
You can identify which agent of erosion transported each sediment by looking at
a few characteristics:
Running Water – sediments that have been transported through
running water appear rounded and smooth and are deposited in
sorted piles.
Glaciers – sediments that have been transported by glaciers appear
scratched, grooved, and are deposited in completely unsorted
piles, because they were dropped during melting. Also, boulders
can only be transported by glaciers.
Wind - sediments that have been transported by wind are appear
pitted (random holes) and frosted (glazed look) and are deposited
in sorted piles. Only very small particles can be transported by
wind.
Gravity – sediments that are transported by gravity are found in
piles at the bottom of cliffs or steep slopes. They appear angular and unsorted.
Mrs. Degl 35
Factors that influence erosional rates (speed) in running
water and glacial ice:
1. Slope (gradient) of the land – as slope increases, the water velocity increases, the particle size that the water can carry also increases, therefore the amount of erosion increases.2. Volume (size of the water or glacier) – as the volume of the water or glacier increases, their velocities increase, the particle size that they can carry also increases, therefore the amount of erosion increases.3. Position within the running water – Water is traveling faster around the outside of turns therefore that is where more erosion occurs. Water is traveling slower on the inside of turns; therefore deposition occurs on the inside.
Deposition
Rock particles that are picked up and transported during erosion will ultimately be deposited
somewhere else
Deposition is the process by which sediments (small
particles of rock) are laid down in new locations.
• Together, Erosion and Deposition build new landforms.
• Deltas
• Canyons
• Meanders
• Floodplains
Water Deposition Deltas – slow river current drops sediment in fan-shaped
pattern at end of river
Sand Bars – offshore deposit of sand, gravel, or shell material
Alluvial Fans
Beaches – deposited sand
Delta
• Where rivers meet the
ocean is called the
mouth of the river.
Soil and dirt carried
by these rivers is
deposited at the
mouth, and new land
is formed. The new,
soil-rich land is known
as a Delta
Mrs. Degl 39
Delta – a fan shaped deposit that forms at the mouth of a
river/stream when it enters a larger body of water. This is seen
under the water. The particles are horizontally sorted.
Mrs. Degl 40
Alluvial Fan - a fan shaped deposit of sediments that forms
when a stream/river flows out of a mountain on to flat, dry plains.
These are not under water and are very visible. This only
happens on the land. You can call it a “land delta”.
Canyons
Canyons are large valleyscreated by a river or stream.
Meander
Meandering streams wander side to side as they constantly
seek out the lowest elevation.
This constant motion creates a series of S-shaped “loops”.
Mrs. Degl 43
Meandering (Curving) River/Stream
Straight Flowing River/Stream
Sediments
are
traveling
the fastest
in the
center
directly
below the
surface.
Erosion
happens
on the
outside of
turns.
Deposition
happens
on the
inside of
turns.
Running
Water
Mrs. Degl 44
Floodplains
• These are low-
lying areas along
the sides of a river
channel that have
regular times of
heavy wate rflow
to cause the river
to spill over and
flood the land.
What did water create in each of these pictures?
DELTA SANDBAR
ALLUVIAL FAN
http://www.school-
portal.co.uk/GroupDownloadFile.asp?file=2160
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1
2
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1 2
4
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BEACH
How does this affect us?Humans are constantly
influencing the nature
of our landscapes.
HOUSES, ROADS,
BUILDINGS,
DEVELOPMENTS,
CANALS, etc., all
change the shape and
appearance of the
land.
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There are 5 ways that man can cause erosion:
1. Forestry – all vegetation of removed,
and without roots, the soil will erode
away.
2. Strip Mining –removing rock cover to
get to the resources below, this causes the
loose sediments to erode away.
3. Construction – the clearing of land to
build buildings/houses also causes all
loose soil to erode away.
4. Improper Farming – not plowing the
land at right angles to slopes causes soil
to erode away.
5. Salting Highways – the salt is washed
off the road to the sides, where it
prevents vegetative growth along the
sides.
Summary please pick ONE
• Use at least two facts from your notes
to explain the question below.
• How does Erosion and Deposition Change the Surface of the Earth?
OR
• How does water and wind change the surface of the earth?
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