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