AP Environmental Science / Unit 4: Earth Systems and Resources
4.2 Soil Formation and Erosion
Notes
Soil forms from weathering of parent rock plus organic matter, over a long time.
- Horizons: O (organic), A (topsoil), B (subsoil), C (weathered parent rock).
- Erosion by wind and water removes topsoil; plant cover reduces it.
Practice
The topsoil layer is horizon:
Mix of humus and minerals.
Which slows soil erosion?
Roots hold soil.
Soil forms from:
Physical, chemical and biological weathering.
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