Unit 4: Soil

weathering

mechanical and chemical processes that cause exposed rock to decompose or break down into smaller parts, creating soil

erosion

process by which the surface of the earth is worn away by the action of water, glaciers, winds,waves, etc.

texture

how something feels to the touch

soil

portion of the earth's surface consisting of disintegrated rock and organic matter

organic matter

made up of living, or once living organisms

sand

Largest of the soil texture classified particles. Consists of small pieces of rocks, made up of small, loose grains, often of quartz.

minerals

inorganic substances (not living), such as quartz or feldspar, usually formed as crystals in the rock cycle.

silt

Second smallest particle of soil. A sedimentary material consisting of grains or particles of disintegrated rock.

clay

Smallest classfied particles of soil. Material that is plastic (moldable) when wet, consisting mostly of hydrated silicates of aluminum

horizons

A horizontal layer in a soil defined by distinictive physical features such as texture and color.

O Horizon

The organic horizon at the surface of many soils, composed of organic detritus in various stages of decomposition.

A horizon

Frequently the top layer of soil, a zone of organic material and minerals that have been mixed together. Also known as topsoil.

B Horizon

A soil horizon composed primarily of mineral material with very little organic matter.

C Horizon

The least-weathered soil horizon, which always occurs beneath the B horizon and is similar to the parent material.

E Horizon

A zone of leaching, or eluviation, found in some acidic soils under the O horizon or, less often the A horizon.

soil degredation

The loss of some or all of a soil's ability to support plant growth.

parent material

The rock material from which the inorganic components of a soil are derived.

leaching

The transportation of dissolved molecules through the soil via groundwater.

permiability

The state or quality of a material or membrane that causes it to allow liquids or gases to pass through it.

porosity

The quality of being porous, or full of tiny holes. Liquids go right through things that have porosity

aeration

The process by which air is circulated through, mixed with or dissolved in a liquid or substance.

infiltration

The process by which water on the ground surface enters the soil.

deposition

Process in which sediment is laid down in new locations.

bedrock

The solid layer of rock beneath the soil.