LEARNING TARGET:I CAN ANALYZE THE EFFECTS OF WEATHERING, EROSION, AND DEPOSITION ON THE ENVIRONMENT IN TEXAS ECOREGIONS.

Weathering, Erosion, & Deposition

The Cycle of Changing Earth’s Surface

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

ErosionDeposition

Weathering

The breaking down and/or wearing away of earth materials (rocks) into smaller pieces

Must occur before erosion can happenNo 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 EcoRegion

Physical Weathering

Enchanted Rock in the Llano Uplift Ecoregion

•Exfoliation-warming and cooling of rocks over time causes rocks to peel into sheets

Chemical Weathering

Chemical 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 Weathering

Natural Bridge Caverns in Texas

Erosion

The movement of weathered earth materials by moving water, wind, gravity or ice

Ex: waves causing beach erosion (shoreline of Texas is disappearing) running water

http://www.glo.texas.gov/what-we-do/caring-for-the-coast/coastal-erosion/causes-of-erosion.htmlEx: sand storm windEx: rain causing a mudslide running water and

gravityEx: landslide gravityEx: 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

•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

The process of eroded earth materials (sediments) being deposited in a new location

Ex: delta-where sediment is deposited where a river flows into an ocean or lake builds up a landform

Ex: sand dune-a deposit of wind blown sand

Deposition

Desert winds sculpted these gentle swirls out of the limestone hills in Black Gap Wildlife Management Area, Texas. This remote, 100,000-acre (40,470-hectare) 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

Please draw this in your notes

Weathering“Break it

down”

Erosion“Move it”

Deposition“Drop it”

WEATHERING & EROSION

For Review

Lets compare

Please draw a Venn diagram and compare chemical and physical weathering.

How are they alike? How are they different?

Physical weathering Chemical weathering