210 white: relations between coal and petroleum 



the Atlantic Coastal Plain formations will be of comparatively 

 low rank, and that those of the Tertiary will not be better than 

 25° or 27° Baume. On the other hand, in the Paleozoic areas 

 of the southern Allegheny region, oil pools of commercial value 

 may, if other geologic factors are favorable, be expected where- 

 ever the fixed carbon of the coals does not exceed 60 per cent 

 in the pure coal, with a less promising possibility of finding pools 

 as far east as the 65 per cent isovol. 



The relations between the rank of the oils and commercial 

 oil field limits on the one hand, to the progressive alteration of 

 the organic detrital deposits on the other, appear to be as sig- 

 nificant in the Cretaceous and Tertiary formations of western 

 America and Mexico as in the eastern Paleozoic areas. 



CONCLUSIONS 



The comparison of the gravities of the oils in different for- 

 mations and regions, with especial reference to the stages of 

 the regional alteration of the mother rocks and other carbonace- 

 ous deposits found in the same formations or in formations 

 overlying the oil pools in the various regions, though it is some- 

 what unsatisfactory on account of the lack of better informa- 

 tion as to the chemical characters of the petroleums, leads to 

 the following conclusions: 



(1) Petroleum is a product generated in the course of the 

 geodynamic alteration of deposits of organic debris of certain 

 types buried in the sedimentary strata. 



(2) The quantity and characters of the oils generated are 

 determined by: (a) the composition of the organic deposit at 

 the beginning of its dynamo-chemical alteration; (b) by the 

 stage in the progress of the dynamo-chemical alteration of the 

 organic substances; (c) by the elimination, under certain con- 

 ditions, of the heavier and more viscous hydrocarbons through 

 filtration incident to migration. How far each of the above 

 mentioned factors is responsible for the characters of the petro- 

 leums remains to be determined by observation and investiga- 

 tion, both in the field and in the laboratory. It is probable 



