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

2. What do you think caused this?

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

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

10. 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

11. Striations- lines showing evidence of movement
ABRASION is 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

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

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

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16. Plant and Animal Action

17. Growth of Plants

18. Biological Weathering18

20. 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. 

22. 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

23. Examples of Chemical Weathering
Oxidation
Dissolution
Carbonation
Acid Rain

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

25. 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

26. 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.

27. Carbonation CO2 dissolves 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.

28. 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.

30. Living organisms
Lichens

31. Acid rain has eaten away this limestone statue.

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