Weathering, Weathering, Erosion, & Erosion, & DepositionDeposition
What are the effects of weathering, erosion, and
deposition on the environment in Texas
Eco-regions?
Weathering, erosion, and deposition act togetheract 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
The Cycle of the Changing The Cycle of the Changing Earth’s SurfaceEarth’s Surface
Please draw this in your Please draw this in your notesnotes
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
WeatheringWeathering
Physical/Mechanical weathering … the breaking down of rocks into smaller pieces (wind, flowing
water, ice, gravity, animals/plants, temperature changes)
Physical WeatheringPhysical Weathering
Physical Weathering -- The steep walls here were carved out by moving water
Palo Duro Canyon in the High Plains Eco-Region
Physical WeatheringPhysical Weathering
Enchanted Rock in the Llano Uplift Eco-region
Exfoliation-warming and cooling of rocks over time causes rocks to peel into sheets
Chemical WeatheringChemical Weathering
This cave was formed by slightly acidic water
dissolving the limestone
Chemical weathering occurs when chemical reactions dissolve the minerals in rocks or changes them into different minerals (rusting, acid breakdown, etc)
Chemical WeatheringChemical Weathering
Natural Bridge Caverns in Texas
Let’s compareLet’s compare
Please draw a Venn diagram and compare chemical and physical weathering. How are they similar/different?
The movement of weathered earth materials by moving water, wind, gravity or ice
Example: waves causing beach erosion (shoreline of Texas is disappearing) running waterhttp://www.glo.texas.gov/what-we-do/caring-for-the-coast/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
ErosionErosion
ErosionErosionGalvestonGalveston Texas before/after Hurricane Texas before/after Hurricane
IkeIke
ErosionErosion
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.
ErosionErosion
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 Why care about erosion?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 Bare Slopes vs. Vegetation Stabilized SlopesStabilized Slopes
How do weathering, erosion and depostion impact each side of the “hill”?
Bare Slopes vs. Vegetation Bare Slopes vs. Vegetation Stabilized SlopesStabilized Slopes
• Mudslide danger
• Loss of topsoil• Clogged storm drains• Flooding problems• Expensive clean up
• Eroded or buried house foundations
Bare Slopes vs. Vegetation Bare Slopes vs. Vegetation Stabilized SlopesStabilized 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
LandslidesLandslides
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.
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
DepositionDeposition
DepositionDeposition
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 area from the Rio Grande River
DepositionDeposition
The Red River carries sediments, and drops some
along the way