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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.
Water is the medium of the oceans, the medium which carries all the substances and elements involved in the marine biogeochemical cycles. Water as found in nature almost always includes dissolved substances, so water has been described as the "universal solvent" for its ability to dissolve so many substances.
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 Group is now divided into a White Chalk Subgroup and a Grey Chalk Subgroup, both of which are further subdivided into formations.These modern divisions replace numerous earlier divisions, references to which occur widely on geological maps and in other geological literature.
The sea bottom was covered with white mud formed from fragments of coccoliths, the skeletons of tiny algae that floated in the surface waters and sank to the bottom and, together with the remains of bottom-living creatures, formed muddy sediments. It is thought that the sediments were deposited very slowly, probably half a millimetre a year ...
It thus converts it into an effluent that can be returned to the water cycle. Once back in the water cycle, the effluent creates an acceptable impact on the environment. It is also possible to reuse it. This process is called water reclamation. [4] The treatment process takes place in a wastewater treatment plant.
For example, chalk is made up partly of the microscopic calcium carbonate skeletons of marine plankton, the deposition of which induced chemical processes to deposit further calcium carbonate. Similarly, the formation of coal begins with the deposition of organic material, mainly from plants, in anaerobic conditions.
The ocean plays a key role in the water cycle as it is the source of 86% of global evaporation. [2] The water cycle involves the exchange of energy, which leads to temperature changes. When water evaporates, it takes up energy from its surroundings and cools the environment. When it condenses, it releases energy and warms the environment.