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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 reduction of blowdown by dealkalization keeps the water treatment chemicals in the boiler longer, thus minimizing the amount of chemicals required for efficient, noncorrosive operation. [2] Carbonate and bicarbonate alkalinities are decomposed by heat in boiler water releasing carbon dioxide into the steam.
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 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.
Niobrara Chalk was weathered and opalized in the Valentine phase of the Ogallala Formation. The Niobrara Formation / ˌ n aɪ. ə ˈ b r ær ə /, also called the Niobrara Chalk, is a geologic formation in North America that was deposited between 87 and 82 million years ago during the Coniacian, Santonian, and Campanian stages of the Late ...
When heating hard water on the stove, these gas bubbles form on the surface of the pan prior to boiling. Gas exsolution can also occur when the confining pressure is released such as removing the top off a beer bottle or where subsurface water is flowed into an atmospheric pressure tank.
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.
Large areas of clay-with-flints, derived from the weathering of material overlying the present day chalk, occur across the North Downs. One particular suite of sediments that occur in the Guildford vale is known as the Headley Formation and comprises gravel and sand on top of the chalk. These sediments contain marine fossils and were probably ...