1. Section 12.1 Weathering

2. 2 major types of weathering
Mechanical
Chemical

3. Mechanical weathering
Ice and water
frost wedging – water seeps into cracks in rock. It expands when it freezes causing the crack to expand. When this occurs over and over rocks can break into smaller pieces.

4. Abrasion
Striking rock with sand, pebbles, and even other large rocks.

5. Plants and animals
The breakdown of rock
due to plant and animal
activity.

6. Upward expansion
Rock outcrops are lifted
exposing them to
weathering.

8. Chemical weathering Hydrolysis
as water leeches through the soil it picks up ions that are
often deposited
in caverns below.

9. Oxidation
when oxygen reacts with rock outcrops, breaking them down.
This process usually
produces rust.

10. Rates of Weathering Surface Exposure Composition of rock Climate
More surface area more weathering
Composition of rock
Some rocks weather better than others
Climate
Some climates are more conducive to weathering

11. Section 12.2 Soil

12. How soil forms Soil loose weathered rock and organic matter.
Parent material
the material in which soil is formed from.

13. Where soil comes from Residual soil Transported soil
Soil that sits above the bedrock it was formed from
Transported soil
Soil that has been transported to a new location

14. Soil profile Soil horizons
A cross section of the soil that makes up a particular area.
Soil horizons
The individual zones or layers that make up the soil profile

15. Types of soil Topsoil Subsoil C horizon
A horizon, top layer dark in color, and it contains humus (organic matter)
Subsoil
B horizon, red or brownish due to greater iron content, contains clay
C horizon
Older more weather layer, larger fragments of rock

16. Soil composition Soil is dependant on the climate. Temperature
Precipitation
Plant matter
Bedrock

17. Section 12.3 Mass Movements and Erosion

18. Mass movement vs. erosion
Mass movement is the downhill transportation of material caused by gravity.
Erosion is the transportation of material due to wind or water.

19. Mass movement Landslide – the mass movement of bedrock downhill
Talus – weathered rock
fragments that have been
pulled downhill

20. Creep slow movement of soil downhill

21. Slump occurs when the
underlying rock is
eroded and the soil
above give way.

22. Earthflow vs. Mudflow
Earthflow is a landslide that occurs in water saturated areas.
Mudflow is a massive movement of water downhill that contains high amounts of clay and silt.

23. Section 12.4 Soil as a resource

24. Soil fertility Soil fertility is the ability for soil to grow plants.
The amounts of minerals, water, and organic matter determine what plants are able to survive in that particular area.

25. Soil depletion occurs when soil gradually looses its nutrients and can no longer sustain crops.
How can we prevent this from happening?

26. Salinization is when irrigation brings in minerals that can add salt deposits to the soil decreasing its fertility.

27. Erosion and soil concervation
Windbreaks slow the wind preventing or decreasing wind erosion.

28. Contour farming is a method of farming that inhibits water from flowing downhill rapidly.

29. Terraces are flattened areas along slopes that slow the speed of runoff.

30. Strip-cropping is a method where farmers alternate different types of crops. Some maybe tall crops like corn while others are ground covering crops like alfalfa.

31. What other methods can we use in order to prevent erosion?
What methods are used around here?