🌋 APES Geosphere Unit Study Guide (4.1, 4.2, 4.3, 4.6)

Convergent Boundary

Two tectonic plates moving towards each other.

Subduction

The process where the denser plate moves under the less-dense plate.

Divergent Boundary

Two tectonic plates moving away from each other.

Seafloor Spreading

Magma fills the space between diverging plates, forming new rock.

Transform Boundary

Two tectonic plates sliding past each other in opposite directions.

Soil Horizons

Layers of soil that develop through soil formation processes.

Organic Layer (O Horizon)

The uppermost layer of soil consisting of organic material such as humus.

Topsoil (A Horizon)

Layer of soil that is a mixture of organic materials and minerals.

Eluviated Horizon (E Horizon)

Zone of leaching where nutrients are washed from upper to lower horizons.

Subsoil (B Horizon)

Zone of accumulation where minerals like iron gather.

Parent Rock (C Horizon)

Partly weathered rock that serves as the original material for soil.

Bedrock (R Horizon)

Unweathered rock that lies beneath the soil layers.

Water Holding Capacity

The maximum amount of water that soil can retain under gravity.

Cation Exchange

The process by which soil particles attract and hold positively charged ions.

Soil Compaction

The density of soil particles which impacts porosity and aeration.

Soil Texture Triangle

A tool used to classify soil based on percentages of clay, silt, and sand.

Erosion

The process by which soil is removed from its location, often by water or wind.

A channel (stream, river) that concentrates runoff (water) to the main discharge point (a large body of water).

Watershed

Headwaters

Beginning of a watershed