1. Weathering and Soil Formation
CHAPTER
NEW CHAPTER
Weathering and Soil Formation
the BIG idea
Natural forces break rocks apart and form soil, which supports life.
4.1
Mechanical and chemical forces break down rocks.
4.2
Weathering and organic processes form soil.
4.3
Human activities affect soil.
CHAPTER OUTLINE

2. 4.1 Mechanical and chemical forces break down rocks.
weathering
mechanical weathering
exfoliation
Over time, mechanical weathering breaks a rock into smaller pieces.
abrasion
chemical weathering
SECTION
OUTLINE

3. 4.1 Mechanical and chemical forces break down rocks.
weathering
mechanical weathering
exfoliation
Chemical weathering affects exposed rock surfaces
abrasion
chemical weathering
SECTION
OUTLINE

4. 4.1 weathering Mechanical and chemical forces break down rocks.
mechanical weathering
The process by which natural forces break down rocks.
exfoliation
abrasion
chemical weathering
KEY CONCEPT
SUMMARY

5. mechanical weathering
4.1
Mechanical and chemical forces break down rocks.
weathering
mechanical weathering
mechanical weathering
The breakdown of rock into smaller pieces of the same material without any change in its composition.
exfoliation
abrasion
chemical weathering
KEY CONCEPT
SUMMARY

6. 4.1 exfoliation Mechanical and chemical forces break down rocks.
weathering
exfoliation
mechanical weathering
In geology, the process in which layers or sheets of rock gradually break off.
exfoliation
abrasion
chemical weathering
KEY CONCEPT
SUMMARY

7. 4.1 abrasion Mechanical and chemical forces break down rocks.
weathering
abrasion
mechanical weathering
The process of wearing something down by friction.
exfoliation
abrasion
chemical weathering
KEY CONCEPT
SUMMARY

8. 4.1
Mechanical and chemical forces break down rocks.
weathering
chemical weathering
mechanical weathering
The breakdown or decomposition of rock that takes place when minerals change through chemical processes.
exfoliation
abrasion
chemical weathering
KEY CONCEPT
SUMMARY

9. Weathering and organic processes form soil.
4.2
Weathering and organic processes form soil.
Soil has measurable properties, such as color, texture, pore space, and chemistry.
humus
soil horizon
soil profile
Soil is a mixture of weathered rock, organic matter, water, and air.
Plants, microorganisms, and animals affect soil characteristics.
SECTION
OUTLINE

10. 4.2 humus Weathering and organic processes form soil.
soil horizon
The decayed organic matter in soil.
soil profile
KEY CONCEPT
SUMMARY

11. 4.2 soil horizon Weathering and organic processes form soil.
humus
soil horizon
soil horizon
A soil layer with physical and chemical properties that differ from those of soil layers above or below it.
soil profile
KEY CONCEPT
SUMMARY

12. 4.2 soil profile Weathering and organic processes form soil.
humus
soil profile
soil horizon
The soil horizons in a specific location; a cross section of soil layers that displays all soil horizons.
soil profile
KEY CONCEPT
SUMMARY

13. Human activities affect soil.
4.3
Human activities affect soil.
Soil is essential to life and takes a long time to form. It is difficult or impossible to replace soil that has been lost.
desertification
Farming, construction and development, and mining are three human activities that affect soil.
Soil Loss
SECTION
OUTLINE

14. Human activities affect soil.
4.3
Human activities affect soil.
Soil is essential to life and takes a long time to form. It is difficult or impossible to replace soil that has been lost.
desertification
Soil conservation practices help keep soil from blowing or washing away.
Soil Conservation
SECTION
OUTLINE

15. 4.3 desertification Human activities affect soil.
The expansion of desert conditions in areas where the natural plant cover has been destroyed.
KEY CONCEPT
SUMMARY

16. 4.1 Mechanical and chemical forces break down rocks.
I. Mechanical and chemical forces break down rocks.
weathering
A. Weathering breaks rocks into smaller pieces.
mechanical weathering
B. Mechanical weathering produces physical changes in rocks.
exfoliation
abrasion
C. Chemical weathering changes the mineral composition of rocks.
chemical weathering
1. Dissolving
2. Rusting
D. Weathering occurs at different rates.
KEY CONCEPT
SUMMARY

17. Weathering and organic processes form soil.
4.2
Weathering and organic processes form soil.
II. Weathering and organic processes form soil.
humus
A. Soil is a mixture of weathered rock particles and other materials.
soil horizon
1. Soil Composition
soil profile
2. Soil Horizons
B. Climate and landforms affect soil.
C. The activities of organisms affect soil.
D. Properties of soil can be observed and measured.
1. Texture
2. Color
3. Pore Space
4. Chemistry
KEY CONCEPT
SUMMARY

18. Human activities affect soil.
4.3
Human activities affect soil.
III. Human activities affect soil.
desertification
A. Soil is a necessary resource.
B. Land-use practices can harm soil.
1. Farming
2. Construction and Development
3. Mining
C. Soil can be protected and conserved.
KEY CONCEPT
SUMMARY