The principal tenets of the carbon-ratio theory are (1) that the chief agencies in the chemical transformation of carbonaceous deposits, after they have passed through the biochemical stage, are the pressure and the heat derived from horizontal thrust; (2) that as the coals decrease in volatile constituents the oils show a corresponding increase in the lighter and more volatile hydrocarbons, so that low-grade oils are associated with low-rank coals and high-grade oils with high-rank coals; and (3) that where the coals have reached the stage of devolatilization at which their content of fixed carbon constitutes about 65 per cent of their total combustible matter the oils in the coal-bearing and underlying formations have been converted into gases, and where the state of de olatilization is slightly higher the gases have been eliminated.

Inasmuch as a series of coals increases in percentage of fixed carbon with stratigraphic depth in both disturbed and undisturbed areas, and this increase is many times greater than any recorded increase in the horizontal direction, the writer is led to conclude (1) that the geologic agencies producing the chemical transformation of carbonaceous deposits are not so much the heat and pressure incident to horizontal thrust as the heat and pressure incident to depth of burial; and (2) that there is no clear evidence that incipient alteration of sediments has been a factor in determining the extent of our known oil and gas fields and therefore that carbon ratios of coals furnish no information as to the oil possibilities of an area.