238 



ANNUAL REPORT SJVnTHSONIAN INSTITUTION, 1940 



I have already explained how oil fields occur in sedimentary basins, 

 in the folded zones in front of mountain ranges, or in shore-line zones. 

 The U. S. A. have a variety of geologic provinces of various ages 

 fulfilling these conditions, but that is not all. They have tried harder. 

 Every modern device of exploration is rapidly accepted and utilized, 

 but supplementary to both geologist and geophysicist is the wild- 

 catter or the speculator who drills on "hunch" alone. And the wild- 

 catter fulfills an important function. He has not only directly 

 discovered perhaps 20 percent of the total oil of the States, including 

 the biggest of all oil fields, that of east Texas, but he has also in- 

 directly contributed to a greater degree in that both geologist and 

 geophysicist make use of the information from his unsuccessful wells 

 as a guidance for their own locations. A further important factor 

 is that small oil fields which can be produced with profit in an in- 

 tensively industrialized country would not be economically possible 

 if remote from markets or existing pipe lines. 



iSsg jS^s 1909 'i;2-f J92g ic^$4. i()2>5 ^93^ ^937 ^93^ 



Drake's 

 Well 



15000 

 16000 



Figure 4. — Diagram showing increase in depth of the world's deepest welis. 

 (I""l-om Pogue, J. E., BconomicB of the petroleum industry, 1939.) 



