Soil Genesis and Development, Lesson 3 - Soil Forming Factors Glossary

Having a pH lower than 7, having a higher concentration of H+ ions.

As a soil separate, clay refers to mineral soil particles which are less than 0.02 millimeters in diameter. As a soil textural class, clay refers to soil material that is 40 percent or more clay, less than 45 percent sand, and less than 40 percent silt.

Sediments deposited by the running water of streams or rivers. Alluvium may occur on terraces well above present streams, on the present flood plains or deltas, or as a fan at the base of a slope. (SSSA)

Having a pH higher than 7, having a lower concentration of H+ ions.

As a soil separate, clay refers to mineral soil particles which are less than 0.02 millimeters in diameter. As a soil textural class, clay refers to soil material that is 40 percent or more clay, less than 45 percent sand, and less than 40 percent silt.

materials or sediments transported downslope by gravity

The breakdown of a chemical by either chemical or physical reactions that make it inactive.

Land on which the vegetation is dominated by grasses, grasslike plants, and/or forbs. Herbaceous vegetation provides at least 80% of the canopy cover.

Total of the organic compounds in soil exclusive of undecayed plant and animal tissues, their "partial decomposition" products, and the soil biomass. The term is often used synonymously with soil organic matter.

deposits of lake materials

An accumulation of soil, pebbles, rocks, and boulders distributed and marking the lateral edges of a glacier or ice sheet.

deposits of ocean materials

based on the watertable level and the presence or absence of available water to plants (tension less than 1500 kPa) during periods of the year.

The total of the organic compounds in soil, exclusive of undecayed plant and animal tissues, their "partial decomposition" products, and the soil biomass. The term is often used synonymously with humus. (Glossary of Soil Science Terms. Soil Sci. Soc. Am. 1998)

The total of the organic compounds in soil, exclusive of undecayed plant and animal tissues, their "partial decomposition" products, and the soil biomass. The term is often used synonymously with humus. (Glossary of Soil Science Terms. Soil Sci. Soc. Am. 1998)

The unconsolidated, relatively unweathered minerals or organic matter from which soil develops.

Individual rock or mineral fragments in a soil that range from 0.05 to 2.0 millimeters in diameter. Most sand grains consist of quartz, but they can be of any mineral composition.  Sand is also the textural class name of any soil that contains 85 percent or more sand and no more than 10 percent clay.

A soil inorganic separate in the range of 2 to 50 micrometers (or 0.002 to 0.05 mm.). Silt is smaller than sand but larger than clay.

The layers of soil, which make up the soil profile. Soil horizons differ in color, texture, structure and organic matter content.

A vertical section of the soil through all its horizons and extending into the C horizon. For further information, see Soil Genesis and Development, Lesson 4 – Soil Profile Development .

based on mean annual soil temperatures.  Soil temperatures are taken at a depth of 50 cm from the soil surface, using the Celsius (centigrade) scale.

An accumulation of soil, pebbles, rocks, and boulders carried forward, deposited and marking the farthest advance of a glacier or ice sheet.