APES 4.1 Soil formation, Erosion and Its Properties

Igneous rock

• Rock formed directly from magma.

• Rock formed from the compression of sediments.

• Rock formed from the alteration of existing rocks due to heat and pressure.

• Rock formed from the cooling of lava on the Earth's surface.

B horizon

• Commonly known as subsoil, a soil horizon composed primarily of mineral material with very little organic matter.

• The top layer of soil rich in organic material and nutrients.

• A layer of soil that is primarily composed of clay and silt.

• A layer of soil that is often waterlogged and lacks oxygen.

C horizon

• The most weathered soil horizon, rich in organic material.

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

• The topmost soil horizon, known for its high nutrient content.

• A soil horizon that is primarily composed of clay and minerals.

Sand

• Very high porosity, very low water holding capacity, very high permeability.

• Low porosity, high water holding capacity, low permeability.

• Medium porosity, medium water holding capacity, medium permeability.

• Very low porosity, very high water holding capacity, very low permeability.

Rock cycle

• The process of sedimentation and compaction of soil layers.

• The geologic cycle governing the constant formation, alteration and destruction of rock material that results from tectonics, weathering, and erosion, among other processes.

• The cycle of water evaporation and precipitation in the environment.

• The transformation of organic material into fossil fuels over millions of years.

Cation exchange capacity (CEC)

• The ability of a particular soil to absorb and release cations.

• The capacity of soil to retain water and nutrients.

• The measure of soil's acidity or alkalinity.

• The ability of soil to support plant growth.

Acid precipitation

• Precipitation high in sulfuric acid and nitric acid. Also known as Acid rain.

• Precipitation that is low in pH and contains high levels of carbon dioxide.

• Precipitation that is rich in nutrients and beneficial for plant growth.

• Precipitation that occurs only in tropical regions.

Sedimentary rock

• Rock that forms when sediments such as muds, sands, or gravels are compressed by overlying sediments.

• Rock that forms from the cooling and solidification of magma.

• Rock that is formed by the alteration of pre-existing rock through heat and pressure.

• Rock that is formed from the accumulation of organic materials.

Erosion

• The physical removal of rock fragments or soil from a landscape or ecosystem.

• The process of depositing sediment in a new location.

• The chemical breakdown of rocks and minerals.

• The movement of water through soil layers.

Silt

• Low porosity, low water holding capacity, low permeability.

• Moderate to high porosity, moderate water holding capacity, moderate permeability.

• High porosity, high water holding capacity, low permeability.

• Low porosity, high water holding capacity, high permeability.