The unwanted material around ore minerals

The gaps between clints in limestone pavement. They are formed from dissolution of limestone, probably along joints. They are also known kluftkarren.

A channel or pass connecting an atoll lagoon with the open ocean, e.g. at Mururoa Atoll (French Polynesia)

A solid, liquid or gas composed of hydrogen and carbon. Examples include coal, oil and natural gas.

An extended period of time where there is extensive glaciation covering the Earth.

Sea level change on a local scale. Can be caused by glaciers making continents sink or melting glaciers making the continents rise again (isostatic rebound) or local tectonic activity. Combined with the eustatic changes make a relative sea level change.

An isotropic mineral appears opaque in thin section in polarised light.

Other meanings:

• Materials: In the study of mechanical properties of materials, "isotropic" means having identical values of a property in all crystallographic directions.

• Optics: Optical isotropy means having the same optical properties in all directions.

The middle period of the Mesozoic from 199Ma to 145Ma.

Karst topography arises from the dissolution of limestones or evaporites. Typical features include springs, limestone paving, caves and potholes.

See gryke.