white: relations between coal and petroleum 209 



visionally, to place the ultimate limit at the 70 per cent fixed 

 carbon line in the coals, though it is not probable that many 

 large pools will be found near this limit. As related to the oil 

 field limit, as here defined, mention may be made of the evi- 

 dence of the transformation and reduction of the lump resins 

 in the Tertiary and Mesozoic coals when these coals reach a 

 stage of about 68 per cent or 70 per cent of fixed carbon, as I 

 have described in another paper. "'^ It will also be recalled that 

 in the regions of more advanced alteration, as in the semi- 

 bituminous coal fields (75 per cent or more of fixed carbon), 

 the cannels appear to have lost their characteristic fatty char- 

 acters and to have become deadened so as to give essentially 

 the same analyses as the associated humic coals. Field exami- 

 nations indicate that deposits, once cannels, are as numerous 

 in the semi-bituminous g,nd antliracite coal fields as in the average 

 "bituminous" coal field. 



According to the conclusions here given as to oil field limits 

 we appear to have at hand a basis on which to exclude large 

 areas of sedimentary strata from the provinces in which we 

 may, with any hope of success, undertake the costly search for 

 oil by the drill. No oil is reasonably to be hoped for in the 

 Paleozoic formations throughout the greater part, at least, of 

 the area of the Arkansas coal field nor for some distance beyond 

 the margin of this field on the sides toward which the fixed 

 carbon is increasing in direction. Similarly, the very low limits 

 placed on the distribution of oil pools by the regional alteration 

 of the hydrocarbon deposits show the hopelessness of any search 

 for oil in commercial quantities in the Carboniferous or older 

 formations of central and southern New England and of the 

 Appalachian region to the east of the 66 or 70 per cent fixed 

 carbon lines in the carbonaceous deposits. This does not pre- 

 clude the discovery of pools in the overlying Triassic deposits 

 wherever they are not too far altered, nor in the Coastal Plain 

 deposits to the eastward and southward. However, it is prob- 

 able that any commercial deposits of oil that may be found in 



.-"Resins in Taleozoic plants and in coals of high rank, U. S. Geol. Survey, 

 Prof. Paper 85: 65-96. 1913. 



