carbonic acid - A weak acid (H₂CO₃) that forms from the reaction of water and carbon dioxide. Most rain water is a very weak carbonic acid solution formed by the reaction of rain with small amounts of carbon dioxide in the atmosphere.

Creep (deformation): The breaking down of surface rock material by solution or chemical alteration. Common alteration processes are oxidation and hydrolysis.

Erosion:

A general term applied to the wearing away and movement of earth materials by gravity, wind, water and ice.

Exfoliation:

 A physical weathering process in which concentric layers of rock are removed from an outcrop.

Hydrolysis:

A chemical reaction involving water that results in the breakdown of mineral material.

Ice Wedging: 

When water infiltrates fractures in rock and freezes, the force of expansion is great enough to break the rock into smaller pieces.

Landslide:

A downslope movement of rock and soil over a failure surface and under the influence of gravity. Slumps, earthflows, debris flows and debris slides are examples.

Mass Movement:

 A general term used for any downslope movement of rock, soil, snow or ice under the influence of gravity. Includes: landslides, creep, rock falls and avalanches.

Mechanical Weathering:

 A general term applied to a variety of weathering processes that result in the particle size reduction of rock materials with no change in composition. Frost action, salt crystal growth and pressure relief fracturing are examples. Also known as physical weathering.

Mudstone:

 A sedimentary rock composed of clay-size particles but lacking the stratified structure that is characteristic of a shale.

Oxidation:

 A chemical reaction in which substances combine with oxygen. For example, the combination of iron with oxygen to form an iron oxide.

Parent Material:

The rock or deposit from, and on which, a soil has been formed. The nature of the parent rock will largely determine the nature of the Regolith, and hence the soil texture; thus, basalt tends to produce clay soils while granite generally gives rise to sandy soils.

Residual Soil:

the soil that is remaining after the soluble elements have been dissolved

Soil:

 The top layer of the earth's surface, consisting of rock and mineral particles mixed with organic matter.

Soil Profile:

vertical section of a soil, showing horizons and parent material.