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Weathering

Weathering. Create a new entry in your journals titled:. What do you think c aused t his?. http://commons.wikimedia.org/wiki/File:Toad_Rock_-_geograph.org.uk_-_767454.jpg. http://en.wikipedia.org/wiki/File:KharazaArch.jpg. Weathering.

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Weathering

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  1. Weathering Create a new entry in your journals titled:

  2. What do you thinkcaused this? http://commons.wikimedia.org/wiki/File:Toad_Rock_-_geograph.org.uk_-_767454.jpg http://en.wikipedia.org/wiki/File:KharazaArch.jpg

  3. Weathering • Weathering is the breakdown of rock and other substances at the Earth’s surface • Two main types of weathering: • Mechanical • Chemical

  4. Some things in nature that cause weathering • Water running over rocks, causing the rocks to hit one another and break into smaller pieces • Plant roots growing into rocks • Water in cracks in the rock freezing and expanding • Wind carrying sand that wears away rock • Carbon dioxide dissolved in water forming an acid that eats holes in the rock

  5. Mechanical or Physical Weathering • Mechanical weathering – when rocks are broken apart by a physical force. • During mechanical weathering, no new substances are produced. The rock gets smaller, but it stays the same kind of rock. 

  6. Examples of Mechanical Weathering • Ice Wedging • Release of Pressure • Abrasion • Plant and Animal Action New Mexico's Bisti Badlands have been carved by millions of years of mechanical weathering. Mechanical weathering is the process of atmospheric forces, such as rain and wind, wearing away rock and soil. Photograph by Dawn Parker, MyShot Via National Geographic

  7. Ice Wedging – when water freezes in a crack of a rock it expands and pushes the walls of the crack apart eventually breaking the rock

  8. Frost Action or ice wedging slowly breaks up this sedimentary rock into unusual shapes.

  9. Release of Pressure Rocks break off into sheets along joints which are parallel to the surface; caused by expansion of rock due to uplift and removal of surface material that originally buried the rock

  10. ABRASIONis the process of sand and other rock particles carried by wind, water, or ice over an exposed rock surface. This is a picture of a glacier which carves out a U-shaped valley where it flows dragging rocks and boulders along the way. Striations- lines showing evidence of movement

  11. These rocks have been blasted by wind and sand causing them to become rounded. WIND ABRASION

  12. This rock has undergone abrasion from the pond water's sediments for a while.

  13. Plant and Animal Action

  14. Growthof Plants

  15. Biological Weathering

  16. Action of animals • When animals, and some insects as well, burrow in the ground, they loosen and break apart rocks in the soil. Moles, gophers, prairie dogs, ants, and even earthworms cause this to happen. 

  17. Chemical Weathering • Chemical weathering is the process that breaks down rocks using chemical changes. • These changes either break down the rock or weaken the rock to allow for physical weathering. • The main agents of chemical weathering are water, oxygen and weak acids. • It can remove certain minerals from rocks • It can change the minerals into new substances

  18. Examples of Chemical Weathering • Oxidation • Dissolution • Carbonation • Acid Rain

  19. Oxidation • Iron in rock can react with oxygen and water to form rust, making the rock reddish and crumbly.

  20. New substances due to oxidation: • rock softer than original • easier for other forces to break rock apart • “rusting” of the rock • color change in the rock

  21. Dissolution • Dissolving a rock in water is yet another form of chemical weathering, called solution • Solution occurs when compounds are dissolved into water. • Halite, gypsum, and limestone are most susceptible to solution.

  22. Carbonation • CO2dissolves in rain water and creates carbonic acid • Carbonic acid easily weathers limestone making holes in the rock • Rocks such as limestone and dolomite can be entirely dissolved, leaving extensive caverns.

  23. In states with bedrock composed of calcite, such as Florida this process can cause extensive damage to structures above. • Often, caverns are cut out of the rock, the structures on top are heavy, and everything on top collapses into the cavern, leaving what is called a sinkhole. This sinkhole can swallow many houses at a time.

  24. Living organisms Lichens

  25. 1908 to 1969 Acid rain has eaten away this limestone statue. Acid Rain

  26. Exit Ticket • Today I learned that there are two types of weathering - ______________________ and _________________. • An example of each type - • Mechanical - _______________________ • Chemical - _______________________

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