146 THE POPULAR SCIENCE MONTHLY. 



Counties, between thirty-five and forty miles. No oil is found in the 

 horizontal rocks, but it occurs along the disturbed and broken, tilted 

 strata on the edges of the line of uplift. This same belt runs north 

 into Ohio, through Washington and Morgan Counties into Noble 

 County. Volcano, White Oak, and Burning Springs are the principal 

 points in West Virginia. The oil is found in subcarboniferous rocks, 

 ascending to them from the underlying Devonian. 



In Ohio there is another oil-belt, west of the above, beginning in 

 Perry and Morgan Counties on the north, and running south through 

 Athens into Meigs County; and in Cuyahoga and Trumbull Counties 

 are oil-regions closely related to those of Western Pennsylvania. The 

 " Mecca " oil, a valuable lubricating oil, occurs in the Mecca Oil Rocks 

 (Berea grit and Bedford shales) of Trumbull County, Ohio. The total 

 production of Ohio and West Virginia is not over 500 barrels daily 

 (Wrigley). 



The Kentucky oil-district is mainly in Barren and Cumberland 

 Counties, with a small adjoining tract south of it in Overton County, 

 Tennessee. A well in Cumberland County, 191 feet deep, produced 

 300 barrels daily. The abundant supply from Pennsylvania and the 

 difficulty of transportation have prevented these regions from becom- 

 ing well known. 



Origin and Source of Petroleum. At first it was held by many 

 that petroleum was a result of distillation from the bituminous coals, 

 which were found in its vicinity, and this belief was strengthened by 

 the fact that some of the very bituminous coals, such as Cannel and 

 Boghead coal, afforded large quantities of similar oils on being dis- 

 tilled; but, although this is very probably the source of a small 

 amount of oil, yet the larger part of it is now believed to derive its 

 origin from rocks lying below the coal-measures, since the oil-bearing 

 rocks are mostly older than the carboniferous formations. 



Some investigators have ascribed a vegetable origin to petroleum, 

 but most authorities agree in attributing it to animal as well as vege- 

 table agencies. Shales are the most common oil-bearing rocks, and in 

 their formation the organic materials would be finely divided and 

 protected from oxidation. The oil-bearing shales commonly show 

 few vegetable remains, and Dana observes that the absence of distinct 

 fossil animal and vegetable remains points to an abundance of delicate 

 water-plants or infusorial or microscopic vegetable life as the source 

 of the organic material contained in them. Limestones, on the otliur 

 hand, are frequently full of animal fossil remains, showing an animal 

 origin for the oil in them, although it is by no means agreed that the 

 petroleum in certain limestones was derived from organic remains in 

 the limestones and not from other strata below them. In whatever 

 shape the finely-divided material was originally present, it would be 

 finely diffused through the mud, and protected from atmospheric agen- 

 cies, and subsequently the hydrocarbons would be formed from them, 



