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Chalk is so common in Cretaceous marine beds that the Cretaceous Period was named for these deposits. The name Cretaceous was derived from Latin creta, meaning chalk. [10] Some deposits of chalk were formed after the Cretaceous. [11] The Chalk Group is a European stratigraphic unit deposited during the late Cretaceous Period.
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 National Trust, which owns the surrounding areas, plans to return the land to a natural state of chalk grassland and preserve existing military structures from the Second World War. [35] In June 2021, a wildflower meadow on White Cliffs of Dover was named in honour of Dame Vera Lynn.
The density of limestone depends on its porosity, which varies from 0.1% for the densest limestone to 40% for chalk. The density correspondingly ranges from 1.5 to 2.7 g/cm 3 . Although relatively soft, with a Mohs hardness of 2 to 4, dense limestone can have a crushing strength of up to 180 MPa . [ 13 ]
Chalk mining is the extraction of chalk from underground and above ground deposits by mining. [1] Mined chalk is used mostly to make cement and bricks . Chalk mining was widespread in Britain in the 19th century because of the large amount of construction underway (and the Industrial Revolution ). [ 2 ]
Chalk is a type of sedimentary rock, composed predominantly of calcium carbonate. Chalk may also refer to: The Chalk Group, a stratigraphic unit in northwest Europe. The Chalk country, a region of Discworld; Blackboard chalk and sidewalk chalk, a material used for writing and art, usually composed of calcium sulfate or calcium carbonate.
Trump’s political rebirth is unparalleled in American history. His first term ended in disgrace, with his attempts to overturn the 2020 election results culminating in the attack on the U.S ...
Chalk is applied to the tip of the cue stick, ideally before every shot, to increase the tip's friction coefficient so that when it impacts the cue ball on a non-center hit, no miscue (unintentional slippage between the cue tip and the struck ball) occurs. Chalk is an important element to make good shots in pool or snooker.