Chalk - Wikipedia
Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor.
Chalk | Properties, Composition, Formation and Uses - Geology …
2023年10月10日 · Chalk is a soft, white, porous, sedimentary rock composed primarily of the mineral calcite (calcium carbonate). It is often associated with marine environments and is characterized by its distinctive white color and powdery texture.
Chalk: A biological limestone formed from shell debris - Geology.com
Chalk is a biological limestone derived from the tiny calcium carbonate shells of foraminifera and the calcareous remains of marine algae. It is soft, friable, porous, permeable and usually white to light gray in color.
5.5: Classification of Sedimentary Rocks - Geosciences LibreTexts
2024年4月11日 · Chalk is a soft, white, porous, sedimentary carbonate rock, a form of limestone composed of the mineral calcite. It forms under reasonably deep marine conditions from the gradual accumulation of minute calcite shells (coccoliths) shed from micro-organisms called coccolithophores.
Chalk: Composition, diagenesis and physical properties
2007年12月1日 · Chalk is a sedimentary rock of unusually high homogeneity on the scale where physical properties are measured, but the properties fall in wide ranges. Chalk may thus be seen as the...
Chalk | Sedimentary, Limestone, Calcium Carbonate | Britannica
chalk, soft, fine-grained, easily pulverized, white-to-grayish variety of limestone. Chalk is composed of the shells of such minute marine organisms as foraminifera, coccoliths, and rhabdoliths. The purest varieties contain up to 99 percent calcium carbonate in …
Chalk - Encyclopedia.com
2018年6月8日 · chalk A very fine-grained white rock composed of the fossilized skeletal remains of marine plankton known as coccoliths and consisting largely of calcium carbonate (CaCO 3). It is the characteristic rock of the Cretaceous period.
Chalk Group - Wikipedia
The Chalk Group (often just called the Chalk) is the lithostratigraphic unit (a certain number of rock strata) which contains the Upper Cretaceous limestone succession in southern and eastern England. The same or similar rock sequences occur across the …
Chalk - Natural Atlas
Chalk is a soft, white, porous, sedimentary carbonate rock, a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton which had fallen to the sea floor. Chalk is common throughout Western Europe, where deposits underlie…
Chalk - Geology is the Way
A chalk is a soft, friable variety of limestone consisting of poorly lithified calcareous ooze, produced by the accumulation of planktonic organisms in a pelagic (open sea) environment.