SLOW Processes that Shape the Earth PART 1. WEATHERING

SLOW Processes that Shape the Earth Part 1. WEATHERING

Mrs. WrightHugh B. Bain Middle SchoolCranston, RI

SLOW Processes that Shape the Earth

PART 1. WEATHERING1Earth - developed over long periods of time through continual change processes.

STUDENTS:Evaluate slow processes of 1) weathering 2) erosion and 3) mountain building. The following slides are on weathering.Determine how the earth has changed and will continue to change over time.

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Weathering What is it?Mechanical (physical) and chemical processes that break down rock at Earths surface

Mechanical Weathering

Chemical Weatheringrock physically broken into smaller pieces

rock breaks down from exposure to water and atmospheric gases (CO2, O2, and H2O vapor).

ukstonehenge.jpg3What is it?Type of weathering where rock is physically broken into smaller pieces Mechanical Weathering4Causes of Mechanical Weathering Freezing & Thawing Release of Pressure Plant Growth Action of Animals Abrasion

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Freezing & ThawingIce wedging

Water freezes in crack in rockExpands and makes crack bigger

Process also causes cracks in sidewalks & potholes in streets http://mail.colonial.net/~hkaiter/science%20images/frostwedging.gif6Freezing & Thawing

http://images.suite101.com/88099_brokenrk.jpghttp://www.google.com/imgres?imgurl=http://upload.wikimedia.org/wikipedia/commons/e/eb/Pothole_Small.jpg&imgrefurl7Release of PressureErosion removes material from rockPressure on rock is reduced Causes outside of rock to flake off like layers of onion

http://www.google.com/imgres?imgurl=http://environment11.pbworks.com/f/1273571046/exfoliation1.jpg&imgrefurl

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Plant GrowthRoots enter cracks in rocksGrowForce cracks farther apart or pry them apart

http://www.google.com/imgres?imgurl=http://video.ecb.org/badger/download/vlc/images/VLC161_Roots_breaking_rocks.jpg&imgrefurl9

http://www.google.com/imgres?imgurl=http://www.wkmctv.com/geo_images/root_wedging.jpg&imgrefurl

Plant Growth10Action of Animals

Burrowing animals loosen and break apart rocks in soilbeeholes.jpg

http://www.google.com/imgres?imgurl11Water vole burrowsbrook-meadow.hampshire.org.ukBurrowing frog

090629081133large.jpgAction of AnimalsWaterVole.jpg567438-Water Vole dungevalley.co.uk

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http://dirttime.ws/Photos/IM002689.jpg

Action of Animalshttp://timenewsfeed.files.wordpress.com/2010/11/106302684.jpg13Abrasiongrinding away of rock by rock particles carried by water, ice, wind or gravity

What is it?riverrocks.jpg14

Abrasion Sand & rock particles carried by wind & water, wear away exposed rock like sandpaper on wood.image002.jpg 569 358-wave action (mechanical weathering) photo courtesy of R. Weller skywalker.cochise.edu15What is it? Type of weathering where rock breaks down from exposure to water and atmospheric gases (CO2, O2, and H2O vapor). Chemical Weathering16Causes of Chemical Weathering Action of Water Oxygen (Oxidation) Carbon dioxide (CO2) Living Organisms Acid Rain

17 Action of WaterMost important cause of chemical weatheringDissolves rock

3572473_f520.jpg 520 390-... formed by chemical weathering. Water dissolves the calcites in the rock ... hubpages.com18Action of Water278.Jpg form where water collects and accentuates rates of chemical weathering uregina.ca

19Oxygen (Oxidation)Iron (Fe), or other metal, combines with oxygen in the presence of waterIf metal is Fe, causes rustRock containing iron also rusts then crumbles apart Rusting causes Red/brown colorWhat is it?

jimeno2.glogster.com20Carbon dioxide (CO2)CO2 dissolves in rainwaterForms carbonic acid that seeps into soil

Easily weathers rocks like limestone & marble chemicalweatheringprocess3.1800X800.jpgRain water and carbon dioxide create carbonic acid. This mild acid interacts ... ehow.co.uk

21Carbon dioxide (CO2)

Cheddarcavesxtrawide.jpg... loses some of its dissolved carbon dioxide and deposits some of its ... geolsoc.org.uk Water seeped into cracks in limestone & cracks enlarged gradually Rainwater became acidic as it dissolved carbon dioxide from the air and soil Dissolved away rock to form cave system

Water dripping from cracks in cave roof, lost dissolved CO2 & depositsCaCO3 Formed stalactites, stalagmites or smooth flowstone22Living OrganismsLichens (plant-like organism) & roots of plants produce weak acidsSlowly dissolve rock around roots trans_s_lichensndstn.jpgStone colonized by lichens, which bit by bit dissolve the rock into .morning-earth.org

23Acid RainCoal, oil, gas burned past 150yrsS, C & N compounds put in airReact chemically with water vapor in clouds Form acids Acids mix with raindrops & fall as acid rainCauses very rapid chemical weathering

_Acid_rain_damaged_gargoyle_.jpg Silverchair Acid Rain lyrics lyricsdog.eu24What is it? How fast weathering occurs Rate of Weathering25Most important factors determining how fast weathering occurs: Type of Rock Climate

26Type of RockMinerals that make up rock determine how fast it weathers If minerals dissolve slowly in water, rock weathers slowly. If minerals dissolve quickly in water, rock weathers quickly.

Rocks.jpgedweb.tusd.k12.az.us27PermeabilityWhat is permeability? Material is full of tiny connected air spaces that allow water to seep through it.

Some permeable rock may weather more quicklyWeathers chemically at faster rate because water easily seeps into it, dissolves it & removes material

28Climateclimate refers to average weather conditions in area

Chemical and mechanical weathering occur faster in wet climatesRainfall provides water needed for chemical changes & physical changes (freezing and thawing)High temperatures - Chemical reactions occur more quickly_

470pxClimateMap_World.png29Rate of Weathering

278.Jpg water collects and accentuates rates of chemical weathering uregina.ca30Looking at the SLOW process of weathering, how has the earth changed over time? Give at least three examples and explain each.

Is the earth still changing through weathering? How do you know? Give at least three examples and explain.

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