Aquifer

Permeable geological formation through which groundwater can flow and from which groundwater can be readily extracted. (See also Groundwater).

Glossary of Terms

Wind Rose

Diagram showing the long-term distribution of wind speed and direction.

Zooxanthellae

Unicellular, symbiotic algae living within coral polyps that produce food for their hosts by photosynthesis and help efficiently recycle low-levels of nutrients.

Pocket Beach

A beach, usually small, in a coastal reentrant or between two littoral barriers (often rocky headlands).

Beach Narrowing

A decrease in the useable beach width caused by erosion.

Natural Resources

May be classified as non-renewable (e.g. coal, oil) and renewable. The latter may further be classified as unconditionally renewable (e.g. solar, tidal or wind energy) and conditionally renewable (e.g. fish, forest products). Conditionally renewable sources will last indefinitely if not over-exploited because that part of the resource that is used can be replaced through natural processes.

Sediment Transport

The main agencies by which sedimentary materials are moved are: gravity (gravity transport); running water (rivers and streams); ice (glaciers); wind; the sea (currents and longshore drift). Running water and wind are the most widespread transporting agents. In both cases, three mechanisms operate, although the particle size of the transported material involved is very different, owing to the differences in density and viscosity of air and water. The three processes are: rolling or traction, in which the particle moves along the bed but is too heavy to be lifted from it; saltation; and suspension, in which particles remain permanently above the bed, sustained there by the turbulent flow of the air or water.

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Aquifer