THE PHILIPPINE 



Journal of Science 



A. Chemical and Geological Sciences 



AND the Industries ^^ , , 



Vol. X JULY, 1915 No./4«# \ 



NOV X 1915 ' 



THE LOCATION OF ARTESIAN WELLS IN THE PHILIPPINeV 4^^y ^, 



ISLANDS FROM A GEOLOGIC VIEWPOINT ' ^^ ^^' """^^ — 



By Wallace E. Pratt 

 {From the Division of Mines, Bureau of Science, Manila, P. I.) 



It will be assumed that the reader is conversant with the 

 principles governing the phenomena of artesian wells, and in 

 the following discussion no attempt will be made to consider 

 the numerous factors which control the subsurface accumu- 

 lation of water under hydrostatic conditions. 



The conditions under which water-bearing rocks, like inter- 

 calated sandstones and shales, were laid down in the Philip- 

 pines, where the distribution of land masses is irregular and the 

 interruption of sedimentary processes by vulcanism was fre- 

 quent, were so variable that no single bed nor any series of 

 beds extends uniformly over great distances. Thus it is not 

 possible here, as it is, for instance, in Australia, to map closely 

 the outcrop of the " intake beds" nor to calculate the depths at 

 which such beds will be encountered over large areas. 



It is probable that very often wells will be drilled at towns 

 which need most urgently a supply of potable water, irrespective 

 of the chances of obtaining water. Frequently there will be 

 little choice between different possible locations in a small town, 

 and it may be found expedient to locate the well on the plaza or 

 at some other central point without taking into consideration 

 any other controlling factors. However, where towns are so 

 situated as to include within their area parts of different geo- 

 logic formations, there may be opportunity to exercise some 

 discretion in choosing a drilling site. 



' Received for publication May 28, 1915. 



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