1. Weathering
Test Date: 2/26/16

2. Weathering Is the breaking- down of rock and sediments over time
Two Types:
Mechanical weathering
Chemical weathering

3. Mechanical Weathering
Physically breaks rocks into smaller pieces
Frost Wedging
Exfoliation/Unloading
Organic Activity

4. Frost Wedging When water freezes it expands 9 %
If water is caught in cracks and freezes it puts stress on the rock and splits it .

6. Exfoliation & Unloading
Rock weathers and erodes.
There is less pressure and weight pushing down on the rock.
*The rock expands upward and breaks into sheets and slabs.

8. Biological Activity Living organisms break down rocks. Roots Lichens
Animals

9. Mechanical Weathering
As a rock weathers it increases the surface area.
This causes the weathering to speed up

10. Chemical Weathering Breaking down (Dissolving) of minerals in rocks
Changing rocks/minerals into different substances.
Occurs when rocks react to air, water, and other chemicals

11. Oxidation
Rocks are exposed to oxygen and water. If the rock is exposed to water and oxygen.
The Iron oxidizes and turns red.
This is the same process that causes rust on metal.

12. Acid Reactions
When water reacts with carbon dioxide it forms carbonic acid.
The acid reacts with rocks that contain calcite (limestone).
The rocks dissolve.
Acid rain speeds this process up.

13. Factors affecting weathering
1. Composition of rock
2. Surface Area

14. 3. Climate
The warmer and more humid a region is, the more weathering occurs

15. SOIL

16. Factors affecting Soil Formation
Climate
Warmer and wet = More weathering
Slope of the Land
Erosion removes soil forming materials
Types of rocks weathering
Some rocks weather easier than others
Types of Vegetation
Vegetation adds organic matter and aids in soil formation
Amount of Time
More time = Richer Soils

17. Soil provides
support and nutrients
for plant growth

18. Weathering
breaks down rocks to create soil. It can be caused by weather, water, or living things

19. There are five components of soil:
1. Rock
2. Sand
3. Silt
4. Clay
5. Humus
Can you match each type of soil to its picture?

20. Rock is solid and made of minerals

21. Sand
Sand is tiny grains of worn down rock. It doesn’t hold water or have many nutrients.

22. Sand ------------Silt---------------Clay
Silt is very small, broken pieces of rock. It is larger than clay, but smaller than sand. It is powdery when dry.
Sand Silt Clay
(smaller particles) (larger particles)

23. Clay is used for adobe or brick houses.
Clay holds water well. It is sticky and can be shaped when it is wet. But, it is very hard when dry.
Clay has many nutrients.
Clay is used for adobe or brick houses.

24. Humus
Humus is made of leaves, twigs, small animals, or other decayed substances.
Humus adds many nutrients to the soil.
Humus is in the topsoil.

25. 3 Layers of a Soil Profile
Topsoil (The layer on TOP)
Subsoil (The prefix SUB means under)
Bedrock ( The type of bedrock determines the type of soil)

26. Soils are dynamic, they change over time
Parent
material
Young
soil
Mature
Old
Time

27. As soils age, they form distinct soil horizons and a soil profile
topsoil
subsoil
parent material

28. Soil Triangle for identifying soil 60% sand, 30% silt, 10% clay

29. Soil as a Natural Resource!
Made by NATURE
Cannot be replaced
Must be conserved (saved)!

30. Ways to Conserve Soil Plant trees Plant grass Healthy farming
Plant gardens to grow crops
What else can you do to conserve soil?

31. Erosion
Erosion - the transport of materials from one place to another.
Erosion can be performed by water, wind, and ice (glaciers)

32. Erosion by water Major agent of erosion
Rain carries away bits of soil and sediment
Rain creates large valleys
Erosion by water changes coastlines
Grand Canyon created by water erosion

33. Erosion by wind
Wind can carry dust, sand, and volcanic ash from one place to another
Ex. Arches National
Park

34. Erosion by Ice
As glaciers move slowly over the land, they pick up rocks and boulders.
These rocks are transported by the glacier.
The glacier itself erodes the ground beneath.