The Elements of economic geology

Bibliographic data

Monograph

Identifikator:: 1773832379

URN:: urn:nbn:de:zbw-retromon-172798

Document type:: Monograph

Author:: Gregory, John W. http://d-nb.info/gnd/11683014X

Title:: The Elements of economic geology

Place of publication:: London

Publisher:: Methuen

Year of publication:: 1928

Scope:: XIV, 312 S.; graph. Darst.

Digitisation:: 2021

Collection:: Economics Books

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Chapter

Document type:: Monograph

Structure type:: Chapter

Title:: Part IV. Engineering geology

Collection:: Economics Books

WATER SUPPLY 231 and non-porous, or the increase in temperature, or some obstacle such as a fault or a dyke. If a well be sunk through the overlying impermeable layer, the water will rise in it to a height determined by the pressure-head. If the mouth of the well is lower than the water-charged part of the permeable rock, the water will discharge as a flowing well. If the head of the water does not force it to the top of the well it can be obtained by pumping or baling, or, as in the air-lift pump, by the injection of compressed air, the expansion of which lifts the water to the surface. One well-known variety of flowing well occurs. where a permeable bed is bent into a trough-like fold or syncline u on i ora | S F16. 59.—CIRCULATION OF WATER Circulation of water in a porous limestone, L, between two impermeable beds. U.S., Upper shale, and L.S., Lower shale; D, Dyke; W.T,, Water-table if D were absent and the limestone had a discharge at lower end. Hs.S., Hydrostatic Surface, owing to blockage of flow of water by the dyke, D; Hl, Level of Hydraulic Surface if dyke were absent, In the 5 wells the solid part indicates the water-level as it would stand in wells 1-4, if the dyke were absent. No. 4 would be a Jowing well; with the dyke present water in that well would rise in a pipe to Hs.S. No. 5 would be dry owing to the dyke. between two impermeable beds; when the deeper part of the water-bearing layer is reached by a bore the water overflows at the surface owing to the pressure of the water in the upper part of the * U-shaped sheet of permeable rock. Such wells were called artesian from those at Artois in Flanders. The term has been used so widely that it has lost its meaning. It is used in America for all deep wells. In the British well sinking industry it is used for bored wells in distinction to dug wells. Flowing wells due to the pressure of water at a higher level in a water-bearing bed in a synclinal are widespread, as in the London and Paris basins. Flowing wells due to simple water pressure also occur where the beds are inclined in one direction, as along the coast of

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