Geology Glossary

Bedding

A characteristic of sedimentary rocksin which parallel planar surfaces separate layers of different grain sizes or compositions deposited at different times.

Cleavage

The tendancy of a rock or mineral to break along certain prefered planes.

Dip

The angle between the plane being measured and horizontal, as measured in a unique vertical plane, perpedicular to the strike.

Erosion

The set of all processes by which soil and rock are loosened and moved downhill or downwind.

Fault

A planar or gently curved fracture in the earth's crust across which there has beenrelative displacement of the two blocks of rock parallel to the fracture.

Igneous Rock

A rock formed by the solidification of a magma

Metamorphic Rock

A rock whose original mineralogy, texture, or composition has been changed by the effects of pressure, temperature, or the gain or loss of chemical components.

Mineral

A naturally occurring, inorganic, crystalline solid with a specific chemical composition.

Sedimentary Rock

A rock formed by the accumulation and cementation of mineral grains by wind, water, or ice transportation to the site of deposition of by chemical precipitation at the site.

Stratification

The characteristic layering or bedding of sedimentary rocks.

Strike

The angle between a horizontal line on a plane and true north.

Superposition

The principle that, except in extremely deformed strata, a bed that overlies another bed is alway younger.

Weathering

The set of all processes that decay and break up rock, by a combination of physical fracturing and chemical decomposition.