204 white: RELATIONS BETWEEN COAL AND PETROLEUM 



In the Coastal Plain regions of Texas and Louisiana, where 

 the coals of the Tertiary formations have not passed the stage 

 of brown lignites, the oils of the associated beds are low in rank, 

 with gravities falling, in most cases, between 17° and 24°, though 

 tests of samples from certain localities are reported to show a 

 gravity as low as 33° Baume. The Tertiary oils in California 

 are, on the whole, similar in gravity range. Some notable fluc- 

 tuations in the oils of this State are apparently to be accounted 

 for as due to deteriorated samples, to losses through porous 

 covering strata, to local dynamic action, etc. A number of 

 samples of oils of exceptionally low gravity from this State, as 

 well as from the Olympic region of Washington, may owe their 

 peculiarities to filtration or to greater local alteration of the 

 rocks in folded districts. These exceptions affect but slightly 

 the general average of the pools or fields. The Cretaceous rocks 

 in northern California, in which the alteration of the carbonace- 

 ous deposits is more advanced, appear to contain oils of dis- 

 tinctly higher rank, corresponding to the oils in sub-bituminous 

 areas or in regions of low rank bituminous coals. In the Coalinga 

 field, the middle Tertiary oils, many of which may have probably 

 suffered losses, average between 18° and 20° Baume, but a grav- 

 ity of 34° is reported for the oil in the Cretaceous underlying 

 the anticline at Oil City at the northern border of this field. 

 Similarly, the oils in the Texas Cretaceous, which carries sub- 

 bituminous coals, range from 32° to 39° in gravity; the still 

 higher grade oils, ranging from 39° to 43° in gravity, in the Caddo 

 field of Louisiana, are found in sands near the base of" the L^pper 

 Cretaceous."'^ 



In Wyoming the evidence is somewhat conflicting, apparently 

 on account of the nature of the samples tested, many of these 

 having been taken from springs or from wells of so light pro- 

 duction or of so shallow a depth as to be subject to the effects 

 of either evaporation or contamination. It appears, however, • 

 that the oils from rocks of the lignitic stage of alteration in this 

 State average about 22° to 24° in gravity, while the oils from 



" Caddo Lake is probably over the westward trending Appalachian coal meas- 

 ures and may possibly have derived its oils from the latter. 



