Post on 22-Feb-2016
description
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
Karst Topography—an area where there is a layer of limestone near the surface that groundwater erosion can significantly change the shape of the land. Deep valleys and caverns are common, but surface streams are rare because the water sinks easily down into the weathered limestone. Sinkholes are common.
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
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
What is an ecoregion?
A relatively large unit of land or water that is characterized by a distinctive climate, ecological features and plant and animal communities (Source: National Geographic’s Strange Days on Planet Earth