The Elements of economic geology

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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

220 ECONOMIC GEOLOGY smoke, acids, and bacteria. Snow collected off the roof of the Lancet Office in London contained ~— Soot, coal dust, and tar . Mineral matter in solution Organic matter in solution Free ammonia . Organic ammonia Sodium chloride Sulphuric acid Nitric acid 30°32 grs. per gall, 420 ,, 784 ” 07 01 3; 3:30 1” Traces. The rain near the sea contains sea-salt derived from evaporated spray, and some is carried far inland. This salt is harmless in moderate quantities, but introduces uncertainty in the use of chlorine as a test of organic pollution. ConnaTE—Some water is enclosed in sedimentary rocks during their deposition and is stored in them as “ connate water.” Prutonic or JuveniLE WaTer—There was for long wide- spread reluctance to admit the existence of any water on land other than that derived from the rain. Deep wells, hot springs, and volcanoes were regarded as all discharging meteoric water which had percolated underground and been forced to the surface, either by the internal heat of the earth, or by the pressure of water at higher levels in the water- bearing bed. Thus at the Conferences on * Water Supply and Distribution ” in 1884, G. J. Symons, the meteorologist, declared that “all water supply comes from the clouds,” and James Mansergh, representing the engineers, said ** all supplies of water, whether found upon the surface or below it, in underground depths, are derived from the rain which falls upon the earth.” C. S. Slichter (U.S.G.S.. Wat. Sup. Pap., 67, 1902) adopts the same view. Geologists have long held that the rainfall is supplemented by water from the interior of the earth, which is described as plutonic, or magmatic, or * juvenile ’ (cf. p. 22). Nearly all primary rocks contain water, which is seen under the microscope in the fluid cavities of quartz in granite. This water usually amounts to between I to 5 per cent. in igneous rocks ; and owing to their bulk a small percentage amounts to a prodigious quantity. This water tends to escape and

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