Changing Earth’s Surface … WEATHERING, EROSION, DEPOSITION Changing Earth’s Surface … http://mrbova.wiki.williamsvillek12.org/file/view/weathering_rock2.jpg/289607043/weathering_rock2.jpg http://www.ratestogo.com/blog/wp-content/uploads/2008/08/triberg-waterfalls.jpg

WEATHERING Surface processes that work to break down rock into smaller and smaller pieces The small pieces are called sediments which become part of the process of soil-formation.

2 Types of Weathering Mechanical & Chemical

Mechanical Weathering Occurs when rocks are broken apart by physical processes The Chemical composition of the rock stays the same (same substance—different shape or form.) SAME http://watermarked.cutcaster.com/cutcaster-photo-100408368-Broken-Rock.jpg

AGENTS OR CAUSES OF MECHANICAL WEATHERING WIND --carries sand and debris which scrapes away at rocks. http://img.ehowcdn.com/article-new/ehow/images/a07/sf/01/type-weathering-occurs-deserts-800x800.jpg http://noeleen.student.cdi.ul.ie/wp-content/uploads/2010/08/arizona-butte.jpg

AGENTS OR CAUSES OF MECHANICAL WEATHERING WATER –as it flows over rocks http://explore.ecb.org/videos/VLC_media?P1=VLC161&REFERER=OTHER Big Bend– Water erosion from the Rio Grande River http://dpsdhaligaon.files.wordpress.com/2007/03/rocks-in-stream-1024x768.jpg

AGENTS OR CAUSES OF MECHANICAL WEATHERING PLANTS –roots, seeds fall into cracks and sprout, breaking them apart more. http://explore.ecb.org/videos/VLC_file?TYPE=Image&P1=1956&REFERER=OTHER#

http://img. geocaching. com/cache/d4fb66d9-ebf4-4328-b116-507cd6ecf624 http://img.geocaching.com/cache/d4fb66d9-ebf4-4328-b116-507cd6ecf624.jpg

AGENTS OR CAUSES OF MECHANICAL WEATHERING ANIMALS– burrowing or pounding of feet on rocks Hey kid, get off the rock! http://sustainablog-org.wpengine.netdna-cdn.com/files/2011/06/goat-herd-china.jpg

AGENTS OR CAUSES OF MECHANICAL WEATHERING PRESSURE– force of something –other rocks falling, movement etc.-causes rock to break http://oldstersview.files.wordpress.com/2007/12/falling-rock.jpg http://www.scienceclarified.com/photos/fault-2840.jpg

AGENTS OR CAUSES OF MECHANICAL WEATHERING TEMPERATURE CHANGES (hot days—rocks expand; cold nights—rocks contract and this causes rocks to crack) http://geology.about.com/od/geoprocesses/ig/mechweathering/exfoliation.htm

http://www.nachi.org/forum/attachments/f23/9357d1172112437-expansion-control-joints-masonry-wall-cohen-017.jpg http://www.msnucleus.org/membership/html/k-6/rc/rocks/3/images/rc3r05.jpg http://www.divinetechies.com/tapl/images/ExpansionJoint.jpg

AGENTS OR CAUSES OF MECHANICAL WEATHERING ICE/FROST WEDGING-- http://mail.colonial.net/~hkaiter/science%20images/frostwedging.gif http://www.sciencephoto.com/image/118866/530wm/C0055123-Frost_wedging_or_ice-fractured_granite-SPL.jpg http://geology2.wikispaces.com/file/view/weathering_2.jpg/273081678/weathering_2.jpg

CHEMICAL WEATHERING Occurs when chemical reactions dissolve the minerals in rocks or change them into different minerals. This changes the chemical composition of the rock, which can weaken/dissolve it.

AGENTS OR CAUSES OF CHEMICAL WEATHERING 1. WATER—MOST IMPORTANT agent of chemical weathering. (many minerals dissolve in water; water mixes with and carries other substances) 2. OXYGEN –oxidation-oxygen reacts with something else (rust, etc.) weakens rocks. http://0.tqn.com/d/geology/1/0/f/X/1/peridrustedandfresh.jpg

A AGENTS OR CAUSES OF CHEMICAL WEATHERING 3. LICHENS AND PLANT ACIDS—roots of some plants or when they decay on rocks, lichens give off acids that break down rock. 4. OTHER ACIDS— Carbonic acid –dissolves minerals in limestone—caves (carbon dioxide + water=carbonation) -Acid rain caused by burning fossil fuels TEXAS CAVES http://cosmictusk.com/wp-content/uploads/FrioBatCave.jpg http://ts4.mm.bing.net/images/thumbnail.aspx?q=4785560495326747&id=f3041ee827c29b155327a96c5349417a

Factors that affect the rate of weathering (how fast they weather) 1. Climate –pattern of weather that occurs in a particular area over many years. *Chemical—more rapid * Mechanical –more rapid in warm, wet (tropical) climates in cold climates (ice) http://www.bbc.co.uk/nature/images/ic/credit/640x395/p/po/polar_region/polar_region_1.jpg http://www.ecosystema.ru/08nature/world/43lao/18.jpg

Factors that affect the rate of weathering (how fast they weather) 2. ROCK TYPES— can also affect the rate of weathering in a particular area because some minerals dissolve easier than others Example: limestone etc. 3. The more surface area (outside) that is exposed to weathering, the faster the rock will weather A. B. “B” would weather faster than “A” because more is exposed to the elements

EROSION *Process that wears away surface and moves them from one place to another (sediments are moved.)

CAUSES/AGENTS OF EROSION 1. Wind (blows) 2. Water (flows) 3. Gravity (pulls) 4. Glaciers (scrape) http://landslides.usgs.gov/research/other/images/Image66.jpg Click here.

MASS MOVEMENT Any type of erosion that happens as gravity moves materials downslope. Ex. landslides—rockslides, mudslides, creep, etc. http://www.cbc.ca/gfx/images/news/photos/2008/07/30/bc-080730-rockslide-cp-FULL.jpg

TAIWAN LANDSLIDE 2010 http://nimg.sulekha.com/business/original700/taiwan-landslide-2010-4-27-6-49-7.jpg

Dropping of sediments that occurs when agents of erosion lose energy DEPOSITION Dropping of sediments that occurs when agents of erosion lose energy

http://canarygeog.canaryzoo.com/Geog1/glacial%20deposition.jpg http://www.buzzle.com/images/geography/river-delta.jpg

and dropped elsewhere (when agents or erosion lose energy) Sediments are broken off Carried Away Weathering Erosion Deposition These processes work together in a cycle that constantly changes Earth’s surface (landforms, shorelines, coastlines, etc.) These processes also help in the formation of soil.

SOIL Mixture of weathered rock, decayed organic matter, mineral fragments, water, and air that can take thousands of years to develop. http://142.23.40.13/courses/st11/images/soil02.jpg

SOIL EROSION Removal or loss of soil due to wind or water. It is harmful in 2 ways: Plants need soil to grow Eroded fertile soil causes sedimentation in (clogs) waterways and releases agricultural pollution into surface waters *Can happen naturally or by humans

SOIL EROSION Soil is eroded when it is moved from where it formed and it occurs when water flows along Earth’s surface or when wind picks up and moves sediment. Many human activities disturb the natural balance between soil formation and soil erosion.

SOIL EROSION 2 Main Categories (Human activities contributing to soil erosion) 1. Construction Remove vegetation, breaking up dirt, etc. Prevention – covering the site with mulch mats, plastic, etc., wetting dirt, plastic fencing around the site. http://www.freeholdscd.org/upload/20080114150024_4500_FSCD-SoilErosion.jpg

SOIL EROSION 2. Farming – Plowing soil, animals overgrazing, removing crops over and over again. Prevention—Alternating crops, shelter belts of trees, terracing on sloped fields which makes shorter slopes, no-till farming. Shelter belts of trees Terracing http://www.forestry.ok.gov/Websites/forestry/Images/windbreaks.JPG

NO-TILL FARMING

STRIP CROPPING

The Basics: Earth's Changing Surface CLICK THIS PICTURE FOR VIDEO : The Basics: Earth's Changing Surface