Module 02
Geology, soil formation and fabric
Where soil comes from and why that matters: weathering, transport and deposition, the clay minerals, and the particle arrangement (fabric) that controls how a soil behaves.
What this module covers
- Explain how soils form by physical and chemical weathering of rock
- Distinguish residual from transported soils and read a transport history from a soil
- Describe the main clay minerals and why smectite swells while kaolinite does not
- Define activity and relate it to clay mineralogy
- Explain soil fabric and structure, and why they make natural soil anisotropic and sensitive to disturbance
Lessons
Weathering, transport and deposition — and the fingerprints they leave on a soil.
Start lesson →Kaolinite, illite and smectite, specific surface, activity and shrink–swell.
Start lesson →How particles are arranged, and why that makes natural soil anisotropic and disturbance-sensitive.
Start lesson →
Module checkpoint
Check what you have taken in
2 questions
Question 1
A chaotic deposit containing everything from clay to boulders, poorly sorted and dense, was most likely transported by:
Question 2
A clay has PI = 18% and a clay fraction of 30%. What is its activity, and is it closer to kaolinite or smectite?