1. By: Katherine Pease 7th Grade Plummer Middle School
Weathering
By: Katherine Pease
7th Grade Plummer Middle School

2. What is Weathering?
Weathering is the breaking down of rock near the surface of the Earth.
A wooden post that soaked for many years in a pool of brine in Owens Lake (dry), eastern California. The grotesque swelling of the wood results from deposition of salts in the wood.

3. What are the two main types of weathering?
Mechanical Weathering
Chemical Weathering

4. Mechanical Weathering, what is that?
It is the process of breaking big rocks into little ones by physical means.

5. What causes this mechanical weathering to happen?
Abrasion
Wedging
Water
Wind
Ice
Plants
Animals

6. What is Abrasion?
Abrasion refers to the breaking and grinding away of solid rock by collisions with moving particles.

7. What is Biotic Weathering?
A form of Mechanical Weathering that is caused by living organisms

8. How do plants and animals cause mechanical / biotic weathering?
Roots and plants push into the rocks and break them apart. They act like wedges and push the rocks apart.
Little animals also help by burrowing and digging through the ground.

9. How does wind cause mechanical weathering?
Some rocks that are composed of soft minerals or are composed of particles that are not well cemented may break down when struck by windblown sand or smaller-sized particles.

10. What is Frost Wedging?
FROST WEDGING. There are already some small cracks in boulders, water gets in the cracks, when that water expands the rock is crunched instead of breaking apart.

11. The pictures in this article are from the summit ridge of Ypsilon Mountain, perhaps one of the best spots in the park to see the effects of frost wedging. You can clearly see in these pictures how the rocks were split apart into plates -- a sure sign of frost wedging at work.

12. What is Salt Wedging?
SALT WEDGING. When it rains and water flows everywhere, it usually have ions and salts dissolved inside.
The water flows in a rock and evaporates. Slowly crystals begin to grow, those crystals act like a wedge and crack the rocks.

13. A wooden post that soaked for many years in a pool of brine in Owens Lake (dry), eastern California. The grotesque swelling of the wood results from deposition of salts in the wood.

14. Ok, but what is Chemical Weathering then?
The breaking down of rocks by changing the molecular make up of the rock.

15. But how does this chemical weathering make the changes?
Through the process of… Oxidation
Hydrolysis
carbonization

16. What do you mean by oxidation?
The process by which oxygen combine with water and minerals in the rock  such as calcium and magnesium.
When iron reacts with oxygen, reddish -brown   iron oxide is formed. The iron-oxide crust crumbles easily and weakens the rock.

17. Oxygen forms with metal to produce a compound.
Oxidation Continued
Oxygen forms with metal to produce a compound.

18. Then what is hydrolysis?
HYDROLYSIS  is…
chemical reaction between the minerals in the rock and hydrogen in rain  water.
For example, during hydrolysis, the feldspar in granite changes to clay mineral which crumbles easily, weakening the rock and causing it to break down.

19. What is carbonization?
process by which dissolved carbon dioxide in rainwater or moisture in  surrounding air forms carbonic acid and reacts with the minerals in the rock.
This process weakens the rock thus breaking it down in the process.

20. What is Erosion?
wearing away of rock: the gradual wearing away of rock or soil by physical breakdown, chemical solution, and transportation of material