CAS GE 100 Lecture Notes - Lecture 23: Parent Material, Weathering, Silt

• School: Boston University
• Department: Geography & Environment
• Course: CAS GE 100
• Professor: Aaron Garrett

Document Summary

Soils hold and provide nutrients, water, and structural support. C horizon is partially weathered parent material. R horizon is solid rock (parent material) Earth worms in o horizon form a horizon, dark and rich in nutrients (most nutrients of any layer) E horizon is leached and as rain comes down, all nutrients go to b horizon (lots of nutrients in b) Factors that form soil (clorpt: climate, organisms, relief (slope, parent material, time. Soil formation: born from top-down from organisms, born from bottom-up from rock weathering, mechanical weathering is physical breakdown. Abrasion physical grinding of rock fragments: chemical weathering. There are 12 soil orders (need to know 4: mollisols is grassland soils. Used for agriculture because soil is rich in nutrients: spodosols are in deciduous forests. Shallow, organic horizon: oxisols found in the tropics. Not a lot of nutrients in soil because tropics are high in productivity. Orange color: arisols found in deserts.