Soil formation, soil horizons, and soil composition basics from an intro Earth science course.
30 cards · basic cards · AI-written, checked twice. Edit anything.
- What are the four main components of soil?
- Rock and mineral particles, organic matter, water, and air
- What is the O horizon?
- Layer of decomposing leaves, twigs, and organic matter at the soil surface
- What is the A horizon?
- Topsoil rich in organic matter and humus, usually dark colored
- What is the B horizon?
- Subsoil where minerals leached from above accumulate, usually lighter colored
- What is the C horizon?
- Layer of partially weathered parent material and rock fragments
- What is the R horizon?
- Bedrock layer of unweathered parent rock
- Define weathering in soil formation
- Physical and chemical breakdown of rock into smaller particles
- What is mechanical weathering?
- Physical breaking of rock by frost action, water, wind, or root pressure
- What is chemical weathering?
- Breakdown of rock minerals through oxidation, hydrolysis, or acid reactions
- What is soil texture?
- The relative proportions of sand, silt, and clay particles in soil
- What is soil structure?
- The way soil particles are arranged and bonded into aggregates
- What is humus?
- Dark, stable organic matter from decomposition of plants and animals
- Name three soil organisms involved in soil formation
- Bacteria, fungi, earthworms, arthropods, and plant roots
- What is infiltration?
- The downward movement of water from the soil surface into the soil layers
- What is percolation?
- The continued downward movement of water through soil horizons
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