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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 crust formed on the lid was ground to powder and boiled with water to remove the calomel. Calx – calcium oxide; was also used to refer to other metal oxides. Chalcanthum – the residue produced by strongly roasting blue vitriol (copper sulfate); it is composed mostly of cupric oxide. Chalk – a rock composed of porous biogenic calcium ...
The chalk and water mixture, also called Kreidemilch or Kreidetrübe, was passed through separation tanks where the finer impurities, the Grand, settled out. The chalk suspension freed from the grand then collected in the settling basin, where the still- suspended particles settled out and accumulated into a layer about 30 cm thick.
It is formed in marine or freshwater environments, often through the activities of algae. Marl makes up the lower part of the cliffs of Dover, and the Channel Tunnel follows these marl layers between France and the United Kingdom. Marl is also a common sediment in post-glacial lakes, such as the marl ponds of the northeastern United States.
The products of chalk weathering are dissolved in rainwater and are transported in stream flow. Chalk streams transport little suspended material (unlike most rivers), but are considered "mineral-rich" due to the dissolved calcium and carbonate ions. The surface water of chalk streams is commonly described as "gin clear".
The name Wold is derived from the Old English wald meaning "forest", (cognate of German Wald, but unrelated to English "wood", which has a different origin). [1] Wold is an Anglian form of the word, as in other parts of England, different variations can be found. [3] Over the years the meaning changed from "forest" to "high forest land".
Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO 4 ·2H 2 O. [4] It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, drywall and blackboard or sidewalk chalk.
Chalk deposits are generally very permeable, so the height of the water table in chalk hills rises in winter and falls in summer. [4] This leads to characteristic chalk downland features such as dry valleys or coombes, and seasonally-flowing streams or winterbournes. The practice of extracting water from this aquifer, in order to satisfy the ...