PALiEONTOLOGICAL REPORT OF GEOLOGICAL SURVEY. 539 



will show more evidently in the examination of coal No. 9, is very 

 probably the one occupied by the following No. 8, or Well coal. 



Coal No. 8. This coal has been crossed in the shaft at Mulford's, 

 where it is two feet six inches thick. But we could not see it, nor ex- 

 amine any of its shales, as the shaft was not accessible. It has been 

 passed through, also, at the Holloway's boring, and has been mentioned 

 in the survey of the Saline Company, always with the same thickness. 

 This indicates a reliable and extensively formed vein of coal, and for 

 this reason, it is especially to be regretted that we did not find a sin- 

 gle opportunity of comparing the fossils of its shales with those of the 

 great Pittsburg coal. The characteristic plants of this remarkable bed 

 are not well defined. The shales immediately above the coal, are very 

 black, bituminous, and covered with stems of ferns without leaves ; 

 these stems are very numerous, and sometimes heaped together in a 

 confused mass. The vein of coal is divided into two, (rarely three stra- 

 ta,) by clay partings, or shales of various thickness, and it is only 

 above its upper roof shales that some leaves of ferns, especially of 

 Neuropterls hirsuta, Lesq'x., and Pecopterls heterophylla, BrgH., are 

 preserved in a reddish ferruginous hard shale. 



It may appear strange that we can refer to a coal, generally acknowl- 

 eged as the thickest and most extensive one, such a thin bed as our 

 No. 8; but, if we follow the Pittsburg coal from its eastern limits, 

 where it attains its greatest thickness, we see it gradually thinning 

 westward, in a remarkably uniform manner. In the Cumberland basin 

 of Pennsylvania it is fourteen feet thick; in Elk Lick township, Som- 

 merset county, eleven feet; in Legonnier valley, Fayette county, and 

 at Pittsburg, nine feet;* at Wheeling, it is already reduced to a little 

 more than six feet, viz : coal one foot, shales one foot, coal five -feet five 

 inches; and at Athens, Ohio, to about five feet, viz: two feet five 

 inches coal, one foot and an half fire-clay or shales, and three feet coal. 

 From Cumberland, Penn., to Athens, Ohio, the distance in a direct line 

 is about one hundred and eighty miles, and from Athens to Mulford's, 

 in western Kentucky, three hundred and fifty miles. If the grada- 

 tion in the decreasing thickness of the vein had continued, without 

 change, the great Pittsburg vein would have been reduced to nothing 

 long before reaching the Kentucky coal-fields. 



•See Lesley's Manual of the coil, p. 81. 



