Chapter 6 



SEDIMENTATION AND GROUND WATER * 



Frank C. Foley 



District Geologist, Ground Water Branch 



U. S. Geological Survey 



Madison, Wisconsin 



Ground water is the water that occurs below the surface of the 

 earth in the zone of saturation. Few, if any, places on the earth are 

 devoid of ground water, though the quantity of it may be small. In 

 most places it is sufficiently plentiful to form all or an important part 

 of the water used by man to sustain life, and in many areas there is 

 enough to operate industry or irrigate crops. The location, develop- 

 ment, and distribution of ground water is a major industry. In the 

 United States the total amount of ground water used in 1945 was 

 about 20 billion gallons a day, nearly double the amount used in 

 1935 (Sayre, 1948). 



The almost universal occurrence of ground water in the crust of the 

 earth makes it an element, either beneficial or detrimental, to be con- 

 sidered in almost all engineering construction projects, in mining, and 

 in petroleum production. It may have to be drained, pumped, or 

 walled out at considerable cost to permit construction or to allow op- 

 eration of projects. Disposal of oil-field brines also is a serious prob- 

 lem in some areas. Ground water has played an essential role in the 

 deposition of many ore deposits. 



The occurrence and recovery of ground water for beneficial use will 

 be discussed in this chapter, rather than its significance in other 

 activities. 



OCCURRENCE OF GROUND WATER 



Though ground water in usable quantities may be found in any kind 

 of rock in which openings occur of sufficient size and continuity to al- 

 low its passage, by far the most prolific aquifers are certain types of 

 sediments, especially stream-laid sands and gravels and cavernous 

 limestones. Volcanic rocks of the Columbia Plateau, the Hawaiian 



* Published by permission, of the Director, U. S. Geological Survey. 



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