208 white: relations between coal and petroleum . 



are of lower gravity corresponding to the lesser alteration of the 

 coals of the region in eastern Kentucky. 



If now, turning to Oklahoma, attention be given to the south- 

 eastern border of the mid-continent oil field, it will again be 

 seen that the commercial pools, so far as discovery has gone, 

 appear not to reach the 65 per cent fixed carbon isovol, though 

 the marginal developments parallel this line. 



In view of the eastward continuation of the oil-bearing for- 

 mations, including the oil sands both in the Appalachian region 

 and in Oklahoma and Arkansas, and taking into account their 

 porosity as ascertained from drillings, and the distinctly favor- 

 able structures, elevations, etc., of the beds — in short, in view 

 of the absence of any other visible geological reasons why com- 

 mercial oil pools do not occur in regions of higher carboniza- 

 tion of the residual organic debris — two questions arise. The 

 first is whether oils, in commercial pools, are anywhere found 

 in or beneath formations in which the regional alteration of the 

 coals is marked by fixed carbon percentages of more than 65 

 or 70. The second question is why the oil stops near this line. 

 As to the first, I can only say that the relations to be observed 

 in other North American oil fields conform to those found in 

 the Appalachian province. Further, that so far as I have had 

 the opportunity to gather the information concerning the oil 

 fields and the coals in other continents, no productive pools are 

 present in such areas of greater alteration.^-' In fact, though 

 the examination of the data is not yet fully completed, it has 

 been carried far enough to make practically certain the con- 

 clusion that commercial oil pools have never been found in 

 regions of further reduction of the carbonaceous detrital deposits, 

 and to establish with nearly equal assurance the conclusion that 

 productive oil pools do not exist in those regions. 



Assuming, however, that variable intensities of thrust, due 

 perhaps to local structures, have permitted the escape of small 

 isolated areas from the more advanced alteration in regions of 

 higher rank carbonization, it may be more conservative, pro- 



^^ Possible exceptions are to be sought in the K;italla field in Aiiiska and in 

 the provinces of Shansi and Shensi in China. 



