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SOIL. Definitions. Bedrock – Solid, un-weathered base rock Regolith – Broken up rock particles. 4 Components of Soil. Rock Material in Soil. Sand - Largest component (2mm – 0.06mm) Composition (parent material) = Quartz Source = Mechanical weathering. Rock Material in Soil.
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Definitions • Bedrock – Solid, un-weathered base rock • Regolith – Broken up rock particles
Rock Material in Soil • Sand - Largest component (2mm – 0.06mm) • Composition (parent material) = Quartz • Source = Mechanical weathering
Rock Material in Soil • Silt (0.06mm-0.002mm) • Composition - feldspar & quartz • Source - mechanical weathering
Rock Material in Soil • Clay - less than 0.002mm • Composition (parent material)– feldspar • Source – chemical weathering
Which soil is best? • Sandy Soil? • Pro vs. Con • Silty Soil? • Pro vs. Con • Clay Soil? • Pro vs. Con
Soil Sizes • Sand (largest) • Silt • Clay (smallest) • Loam (mix of all 3)
Soil Profile • A cross section of soil showing the different layers (horizons) • Horizons • A (O) • B (E) • C DRAW THIS
SOIL PROFILE • A- HORIZON: Organic material • B-HORIZON: area where nutrients from A are “leaching” down. • C-HORIZON: mostly parent bedrock, unweathered material.
SOIL HORIZONS • A- horizontop soilrich in organicshumus- decaying leaves • B- horizonplant roots anchor here • C- horizonbedrock
Thin A + B lots of chemical weathering, but nutrients are used quickly why? Tropical - Rainforest
thin A + B little nutrients little weathering why? Desert Climate
thin A + B few nutrients little chemical weathering why??? Polar soil
Thick A + B lots of nutrients good farmland lots of chem. + phys. weathering why? Temperate Climate
Importance of soil • Food chain • Filters groundwater • 1 cm = 1,000 years formation • Providing resources for world to survive.