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

Usage license:: Get license information via the feedback formular.

Chapter

Document type:: Monograph

Structure type:: Chapter

Title:: Part IV. Engineering geology

Collection:: Economics Books

WATER SUPPLY 229 and metamorphic rocks is insignificant; but their joints may hold useful supplies, especially in the uppermost 10 or 20 feet (e.g. Wisconsin, Geol. Surv. Bull. 35, 1915, p. 350). The renewal of water in wells depends on the rate at which water percolates through rocks; and the movement is usually very slow. It may be a few yards a day through gently dipping sand, or 5 feet a day through a sandstone with a slight dip. The Dakota Sandstone in the west central part of the United States receives much water from rivers that rise in the Rocky Mountains, and it feeds wells far to the E. In part of the area the water flows through the sandstone from one to two miles a year (N. H. Darton, 1897, 18th Ann. Rep. U.S. Geol. Surv., pt. iv, p. 609; also Prof. Pap., No. 32, 1905) ; in Wisconsin, according to Weidman and Schultz (Wisconsin Geol. and Nat. Hist. Surv. Bull. 35, Econ. Ser., 1915, p. 50) the rate seldom reaches half a mile a year, is often only a quarter of a mile a year, or less that 4 feet a day, and may be slower. The hydraulic gradient varies with the permeability of the rocks. Thus in one section the descent of the water-table in the first 6} miles is 74 feet a mile; in the next 16} miles it is 10 feet per mile; in the next 9 miles it is 2 feet per mile; during the last 10 miles near the Mississippi the fall again steepens to about 6 feet per mile. As water percolates underground it usually’ undergoes chemical changes by loss of its oxygen and carbon dioxide, and the solution of material from the rocks. It may become “hard” by solution of bicarbonate and sulphate of lime, or salt by dissolving common salt, or alkaline by dissolving soda and potash; it may also become charged with iron, magnesia, silica, sulphuretted hydrogen, sulphides, sulphates, ste. Subterranean waters may become too salt for domestic or agricultural use, but are usually preserved from organic pollution by the purifying action of the soil. The living soil acts as a filter which absorbs the organic matter in water and destroys noxious germs. If the soil is pierced by a pit or cesspool, water may carry germs into an underlying sheet of sand and gravel; all the water may be infected and a widespread epidemic ensue. The disposal of sewage by cesspools, percolation-wells or dumb-wells is therefore

Access restriction

Copyright

fullscreen: The Elements of economic geology

Monograph

Chapter

Table of contents

Download

Monograph

Chapter

This page

Image fragment

Citation links

Citation recommendation