1898.] PECKHAM — THE GENESIS OF BITUMENS. 131 



well was filled with Devonian shales, that underlie the Bradford oil 

 sand and are supposed to extend from Allegheny county, New York, 

 to central Kentucky ; and in fact to underlie the entire petroleum 

 region that produces Warranite — the pure paraffine petroleums. 

 When ''dry" or unproductive holes are drilled outside the pro- 

 ductive areas, they pass, at the horizon of the oil sands, through a 

 different rock, which is compact and incapable of holding petro- 

 leum. These underlying Devonian shales outcrop at Erie, Pa., 

 and furnish there the material that on distillation yielded fifty gal- 

 lons of distillate to the ton. Where this formation outcrops it is 

 filled with fucoids and has yielded small petroleum and gas wells. 

 The men who drilled Jonathan Watson's deep well told me that, 

 ''the soap stone (Devonian shale) became harder as they went 

 down, and was redder in color, in fact, had been burnt like brick." 

 In a comparatively few localities, petroleum has been found saturat- 

 ing rocks that lie one above the other. The upper rock invariably 

 yields the most dense oil. In 1881 I saw a well in West Virginia, 

 from which the same walking beam pumped at every stroke oil of 

 27 degrees from a depth of 255 feet and oil of 45 degrees from a 

 depth of 600 to 700 feet. 



18. I have never seen a specimen of graphite reported to have 

 come from any locality between the crest of the Alleghanies and 

 the Ozark uplift. This is an uplift of the palaeozoic formation west 

 of the Mississippi river, extending from central Missouri to central 

 Texas. It resembles that of the Alleghanies, but is on a smaller 

 scale. ^ The eastern slope is more abrupt than the western. The 

 formations of the central portions, in Arkansas and the Indian Ter- 

 ritory, are highly crystalline, graphite and anthracite are of frequent 

 occurrence and are found on the western slope. On this slope also, 

 but farther west, in unaltered strata immediately above the crystal- 

 line formations, bitumen occurs in enormous quantity and great 

 variety. Over a large area in the northeastern portion of the In- 

 dian Territory heavy petroleums are found only a short distance 

 beneath the surface, and, as I am informed, below the coal. South 

 of the Red river, in northern Texas, bitumens occur saturating 

 horizontal beds of sand that are intercalated between strata of more 

 or less solid limestone. North of the Red river, in the Indian 

 Territory, every rock formation that is at all porous appears to be 



^ J, C. Braniier, " Former Extension of the Appalachians across Mississippi, 

 Louisiana and Texas," Aj?i. your. Set. (4) iv, 357. 



