Transcript Weathering, Erosion, & Deposition

Weathering, Erosion, &
Deposition
What are the effects of
weathering, erosion, and
deposition on the
environment in Texas
Eco-regions?
The Cycle of the Changing
Earth’s Surface
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Weathering, erosion, and deposition act together in a
cycle that wears down and builds up Earth’s surface
 Weathering-wears down the Earth’s surface
 Erosion - moves the Earth’s surface (acts as a bridge
between the weathering and deposition)
 Deposition - builds up the earth’s surface
Please draw this in your notes
Weathering
Deposition
Erosion
Weathering
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The breaking down and/or wearing away of earth
materials (rocks) into smaller pieces
Must occur before erosion can happen
No movement is involved
Sediments- naturally-occurring
material that is broken down by
processes of weathering;
small/tiny pieces of rock
Physical Weathering
 Physical/Mechanical
weathering …
the breaking down of rocks into smaller pieces (wind, flowing
water, ice, gravity, animals/plants, temperature changes)
Physical Weathering -- The steep walls here
were carved out by moving water
Palo Duro Canyon in the High
Plains Eco-Region
Physical Weathering
Enchanted Rock in the Llano
Uplift Eco-region
Exfoliation-warming and cooling
of rocks over time causes rocks
to peel into sheets
Chemical Weathering
Chemical weathering occurs when
chemical reactions dissolve the minerals
in rocks or changes them into different
minerals (rusting, acid breakdown, etc)
This cave was formed by
slightly acidic water
dissolving the limestone
Chemical Weathering
Natural Bridge Caverns in Texas
Let’s compare
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Please draw a Venn diagram and compare
chemical and physical weathering.
How are they similar/different?
Erosion

The movement of weathered earth materials
by moving water, wind, gravity or ice
 Example: waves causing beach erosion (shoreline
of Texas is disappearing) running water
http://www.glo.texas.gov/what-we-do/caring-for-thecoast/coastal-erosion/causes-of-erosion.html
 Example: sand storm wind
 Example: rain causing a mudslide running water and gravity
 Example: landslide gravity
 Example: rain carrying soil and gravel down a driveway
running water and gravity
Erosion
Galveston Texas before/after Hurricane Ike
Erosion
A gorge is a ravine with nearly vertical
walls. This gorge was cut when heavy
rains pushed a flood over Canyon Lake
Dam in central Texas in 2002.
Erosion
The Bernard Glacier in Alaska's
Saint Elias Mountains looks like
a huge alpine highway.
Glaciers are slow but highly
effective shapers of the land,
essentially carrying away
anything in their path—from
soil and rocks to hills and even
the sides of mountains
Why care about erosion?
 Human activities such as construction increase
the rate of erosion 200, even 2,000 times that
amount. When we remove vegetation or other
objects that hold soil in place, we expose it to the
action of wind/water and increase its chances of eroding.
 The loss of soil from a construction site results in loss of topsoil,
minerals and nutrients, and it causes ugly cuts and gullies in the
landscape. Surface runoff and the materials it carries with it clog
our culverts, flood channels and streams. Sometimes it destroys
wildlife and damages recreational areas such as lakes and reservoirs.
Bare Slopes vs. Vegetation Stabilized Slopes
How do weathering, erosion and depostion impact
each side of the “hill”?
Bare Slopes vs. Vegetation Stabilized Slopes
• Mudslide danger
• Loss of topsoil
• Clogged storm drains
• Flooding problems
• Expensive clean up
• Eroded or buried
house foundations
Bare Slopes vs. Vegetation Stabilized Slopes
• Mudslide danger
• Loss of topsoil
• Clogged storm drains
• Flooding problems
• Expensive clean up
• Eroded or buried
house foundations
• Soil in place
• Less clean up
• Minimum erosion
• Protection
for house
foundations
Landslides
Landslides -- a geological
phenomenon which includes a
wide range of ground
movement, such as rock falls,
deep failure of slopes and
shallow debris flows, which can
occur in offshore, coastal and
onshore environments.
Deposition
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The process of eroded earth materials
(sediments) being deposited in a new location
Example: delta -- where sediment is deposited where
a river flows into an ocean or lake builds up a landform
Deposition
Desert winds sculpted
these gentle swirls out of
the limestone hills in Black
Gap Wildlife Management
Area, Texas. This remote,
100,000-acre area in West
Texas contains some of
the lowest, driest, and
hottest areas in the
Chihuahuan Desert
Deposition
Deposition area from the
Rio Grande River
The Red River carries
sediments, and drops some
along the way