BITUMINOUS AND ANTHRACITIC. 459 



4th. Near Pittsburg, the great coal-seam frequently rests within 

 a few inches of this underlying limestone, in which are a few 

 occasional fossils, all of marine genera. In these places the di- 

 viding layer is only a few inches thick, and consists of a bluish 

 fire-clay. 



5th. In Fayette county, Pennsylvania, the great limestone, 

 which lies above the Pittsburg coal-bed, incloses very generally 

 two thin seams of perfect coal, immediately in contact with the 

 layers of the rock. These coals appear to have considerable 

 range, extending into the adjoining counties. The largest is oc- 

 casionally two and a half feet thick, and a few inches of black 

 calcareous slate alone separate it from the hard limestone. The 

 other coal-bed has a thickness of about one foot, and its surfaces 

 are in equally close contact with the limestone. Neither of these 

 beds is as widely expanded as the including limestone. 



6th. Underneath the uppermost workable bed of coal in western 

 Pennsylvania, or that which I have termed in my Reports the 

 Waynesburg seam, there is a stratum of limestone, which some- 

 times incloses a thin coal-bed, measuring about one foot, 



7th. At Putnam Hill, near ZanesviUe, in Ohio, a bed of lime- 

 stone, five feet thick, rests, according to Dr. Hildreth, on a seam 

 of coal of one foot, there not being more than two inches of fire- 

 clay interposed. The limestone contains Encrini, TerehratulWy 

 and other marine fossils.* 



8th. The same writer mentions, that on the Clear Fork of 

 Little Muskingum, in Ohio, there is a seam of good bituminous 

 cpal, three feet thick, reposing directly on a dark carbonaceous 

 fossiliferous limestone, eight feet in thickness. It is overlaid by 

 another limestone, measuring six feet, from which it is separated 

 by a very thin layer of shale. 



9th. Dr. Hildreth fm-ther states, that on Wills's creek, in the 

 same region, a coal-seam, five feet thick, occurs, resting imme- 

 diately on a bed of limestone, the thickness of which is twenty 

 feet. 



I might cite a large additional number of cases in Pennsylva- 



* Hildreth, in American Journal of Science, p. 31. 



