1. Rocks and Weathering

2. What is Weathering?
Process of breaking down rock into smaller particles
Forces of weathering
Heat and Cold
Oxygen and Carbon dioxide
Water and ice

3. What is Erosion? Process of removing rock particles Forces of erosion
Water
Wind
Ice
Gravity

4. What is Uniformitarianism?
the theory that changes in the earth's crust during geological history have resulted from the action of continuous and uniform processes.
Charles Lyell
Rain erodes mountains
Magma pushes them up
The Earth’s changes are slow processes that occur over time.

5. What is Mechanical Weathering?
Process that physically breaks rocks into smaller pieces
Freezing and thawing
Plant growth
Release of pressure
Acts of animals
Abrasion

6. Mechanical Weathering
Ice wedging
Water seeps into rock
Temperature cools
Water freezes and expands
Deepens the crack
Ice melts
Process repeats

7. Mechanical Weathering
Plant growth
Vascular plant forces or wedges itself into cracks present on the rock and forces the crack to open

8. Mechanical Weathering
Abrasion
Scraping of a rock surface by friction between rocks and moving particles during their transport by wind, glacier, waves, gravity, running water or erosion.

9. Mechanical Weathering
Acts of Animals
Many animals, such as these Piddock shells, bore into rocks for protection either by scraping away the grains or secreting acid to dissolve the rock.

10. Mechanical Weathering
Release of Pressure
Surface material is removed by erosion
Pressure pushes up on the rock
Layers of rock break off to release the pressure

11. What is Chemical Weathering?
Process that breaks rocks through chemical changes
Water
Oxygen and carbon dioxide
Living Organisms
Acid Rain

12. Chemical Weathering
Water
Dissolves salts and reacts with minerals

13. Chemical Weathering Living organisms
Plants that root and grow on rocks produce weak acids that break down the surface

14. Chemical Weathering Oxygen
Oxidation: the process when iron in a rock reacts with oxygen to form rust

15. Chemical Weathering Carbon dioxide Acid Rain
Carbon combines with water to form a weak acid (carbonic acid)
Acid Rain
Burning of fossil fuels produces carbon monoxide, sulfur dioxide, and nitrogen oxide….all of these combine with water to for weak acids

16. What determines how fast?
Type of Rock
Minerals that make up the rock determine rate of weathering
Permeable rock weather faster
Climate
Wet climates weather faster
Warmer climates weather faster