|
Limestone is a sedimentary rock, mainly composed
of mineral calcite. The primary source of
the calcite is usually marine organisms, which settle out of the water
column and are deposited on the ocean floors as pelagic ooze (but see
lysocline for information on calcite dissolution). Secondary calcite may also be
deposited in super-saturated meteoric waters (ground water that reaches
earth's surface as precipitation), as is evidenced by the creation of stalagmites and stalactites. Limestone makes up approximately
10 percent of the total volume of all sedimentary rocks.
Bands of limestone emerge from the Earth's surface in often spectacular rocky outcrops
and islands. For example the Verdon
Gorge in France, Malham Cove in
North Yorkshire, England
and the Ha Long Bay National Park in Vietnam.
It is quarried for roadbeds and gravel roads, building and landscape
construction, and cement manufacture.
See also: marble, list of
minerals, karst, coquina, travertine, chalk, dolomite, quicklime.
|