1. Bell Ringer Test Thursday. Start studying! Type of Weathering
How does it Weather?
Climate
Weathered by:
Mechanical (Physical)
Changes the __________ & ___________ of the rock
_________ & _________ 1. 2.
Chemical
Changes the ________________________ of the rock 3.

2. Soil

3. Soil Development
Soil – the loose covering of weathered rock particles and decaying organic matter (humus) that covers Earth’s bedrock
The result of both mechanical and chemical weathering

4. DID YOU KNOW?
There are more organisms in a handful of soil than there are humans on Earth!

5. Soil Development
Weathering breaks solid bedrock into smaller and smaller pieces
Organisms like bacteria begin to live in these weathered materials
Over time, the organisms die, decay, and add nutrients to the weathered materials to form soil

6. Soil Composition
All soil forms on top of bedrock, a solid layer of rock
Because all soil originates from bedrock, bedrock is called the parent material

7. Soil Composition
The parent bedrock determines the type of minerals in the soil and how long it takes for the soil to form

8. Soil Composition
Residual soil – soil located directly above its parent material
Transported soil – soil that has been moved away from its parent bedrock
Which soil is the result of erosion?

9. Soil Composition Soil profile – vertical sequence of soil layers
Soil horizon – each layer in the soil profile
horizon
profile
horizon
horizon

10. Soil Composition Horizon O: organic layer
Layer of leaves and organic debris at the top of a soil profile
Doesn’t contain weathered rock, so not technically a soil layer

11. Soil Composition Horizon A: topsoil Dark and nutrient-rich
Horizon B: subsoil
Clay minerals, so red with slow water flow
Horizon C: weathered bedrock
Lies just above the bedrock
First horizon to form

12. Soil Conservation
In general, soil formation takes a long time. It can take hundreds of years for just one centimeter (cm) of soil to form!
Soil Conservation – the protection of soil from erosion and/or infertility to ensure that it can be used responsibly

13. Methods of Soil Conservation
Gravity increases erosion on sloped surfaces
Terraces – “stair steps” cut into sloped fields to prevent soil from running downhill
Contour farming – planting rows perpendicularly to the slope to reduce erosion

14. Methods of Soil Conservation
Windbreaks – planting bushes/trees to reduce wind erosion

15. Methods of Soil Conservation
Crop rotation – regularly changing which crops are planted in a particular field to keep the soil fertile
Different plants remove and release different nutrients, so constantly changing the crops replenishes nutrients

16. Effects of Soil Erosion
What happens if soil is not conserved?
Tilling -- Plowing or leaving bare ground, which leaves the soil vulnerable to wind and water erosion

17. Effects of Soil Erosion
In the 1930s, inexperienced farmers in the Midwestern US left exposed soil, creating the Great Dust Bowl
The Great Dust Bowl led to widespread famine and economic loss (paired with the Great Depression)

18. Great Dust Bowl (1930s)

19. Effects of Soil Erosion
In arid (dry) regions, topsoil erosion can lead to desertification
Desertification – the process of good land becoming infertile (unable to grow plants)
This can lead to loss of crops, and as well as famines for both livestock and humans

20. Soil Characteristics
Four major types of soil: polar, temperate, desert, and tropical

21. Soil Characteristics
Soil types vary, even in North Carolina!

22. Soil Characteristics Coastal Plain – sandy soil Piedmont – clay soil
Blue Ridge – rocky, shallow soil

23. Soil Characteristics Fertility – ability to support plant growth
Color – determined by the soil’s climate and composition
Not a clear indicator of fertility (dark soil isn’t necessarily more fertile than light soil)

24. Soil Characteristics Texture – classified by particle size
Smallest to largest particles: clay, silt, sand

25. Soil Characteristics
Soil Texture Pyramid – use the %s of each particle size to classify the soil type

26. Practice: find the point where the %s intersect
20% clay, 40% silt, 40% sand
Loam

27. Practice: find the point where the %s intersect
 60% clay, 20% silt, 20% sand
Clay

28. Practice: find the point where the %s intersect
10% clay, 30% silt, 60% sand
Sandy loam

30. Today
Soil Triangle WS. This is also INDIVIDUAL work. You may ask someone a QUICK question, but you are not working together today.
Vocab. Please listen carefully!!!!

32. After Lab: Work AS A GROUP on the Soil Worksheet
Take turns reading out loud or one person read
When finished, answer the following questions ON THE BACK OF THE WORKSHEET about the soil pyramid:
What type of soil is 30% sand, 60% clay, and 10% silt?
What type of soil is 10% clay, 70% silt, and 20% sand?
What type of soil is 50% clay, 20% silt, and 30% sand?
What type of soil is 60% sand, 30% silt, and 10% clay?
What type of soil is 40% silt, 20% clay, and 40% sand?
Write TWO of your own.
________ type of soil is __% silt, _% clay, and ___% sand.