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Weathering, Erosion, & Deposition What are the effects of weathering, erosion, and deposition on the environment in Texas Eco-regions? How does weathering, erosion, & deposition act together in a cycle that changes the Earth’s surface? Weathering-breaks down the Earth’s surface Erosion - moves the Earth’s surface Deposition - builds up the earth’s surface fc2.galenaparkisd.com Please draw the cycle Weathering Deposition Erosion What is Weathering? The breaking down of rocks into smaller pieces Must occur before erosion can happen No movement is involved Sediments- small/tiny pieces of weathered down rock. What is 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 Palo Duro Canyon in the High were carved out by moving water 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 What is Chemical Weathering? Chemical weathering … dissolving and changing the minerals in rocks into new ones. (Oxidation-Rusting & Acid breakdown) This cave was formed by slightly acidic water dissolving the limestone Chemical Weathering Natural Bridge Caverns in Texas Let’s Compare! Please draw a Venn diagram and compare chemical and physical weathering. How are they similar/different? Physical/Mechanical Chemical Weathering Weathering What is Erosion? The movement of weathered earth materials by moving water, wind, gravity or ice Example Cause of Erosion Waves eroding the beach and East Water TX shoreline Desert Sandstorm in West TX from Wind drought Rain causing Mudslide in the Water & Gravity Rolling Hills of Central TX Landslide on sides of Plateaus of Gravity Central TX Rain carrying soil down a driveway Water & Gravity Erosion Galveston Before and After Hurricane Ike How does Erosion form a gorge? A gorge is a ravine with nearly vertical walls that had its sediment washed away by a river. This gorge was cut with heavy rains pushed a flood over Canyon Lake Dam in central Texas in 2002. How do Glaciers for a gorge? The Bernard Glacier in Alaska's Saint Elias Mountains looks like a huge alpine highway. Heat & Gravity allow Glaciers to move down a slope carrying away anything in their path— soil, rocks, & sides of mountains Why care about erosion? Humans have increased the rate of erosion 200 to 2,000 times faster than normal. What’s Speeding it Up? Removing plants that hold soil in plants, this exposes the land to wind/water erosion. Construction sites removes plants, soil, minerals, & nutrients. Replaced by concrete that increases flooding from surface runoff. How does removing plants effect the erosion on the left side of the hill? How does keeping plants effect the erosion on the right side of the hill? • Mudslide danger • Loss of topsoil • Clogged storm drains • Flooding problems • Expensive clean up • Eroded or buried house foundations • Mudslide danger • Soil in place • Loss of topsoil • Less clean up • Clogged storm drains • Minimum erosion • Flooding problems • Protection • Expensive clean up for house • Eroded or buried foundations house foundations What are landslides? Landslides – Movement of sediment down hill due to gravity. Example: Rock falls on the edges of plateaus & cliffs. What is Deposition? When eroded sediments are deposited in a new location Example: delta -- where sediment is deposited where a river flows into an ocean or lake builds up a landform Before After Deposition W. Texas Example 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 Let’s Practice, write in your S.J. what type of erosion shaped these landforms! Water, Wind, Gravity, Ice?
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