BITUMINOUS AND ANTIIRACITTC. 437 



argument, that a group of coal strata, somewhat lower in the for- 

 mation than the main series, does reach, at intervals, as far east- 

 ward as the margin of the great valley, in a number of localities 

 between the Potomac river and the Tennessee line. Restricting 

 our attention, at present, however, to those districts where the main 

 coal series is developed, we meet with the most ample proofs 

 that all the strata in the insulated basins are precisely on the 

 same geological horizon, as those of the gi'eat basin west of the 

 mountains. These coal rocks all repose conformably on the 

 same easily recognized formation, the great coal conglomerate, 

 with the upper beds of which the lower seams are very generally 

 intersti'atified. This fact, but more especially the circumstance 

 that I have traced many of the principal coal seams and beds of 

 fossiliferous limestone from basin to basin, fully demonstrates that 

 all these detached troughs, however insulated and remote from 

 the main mass at present, were, at the period of their deposition, 

 united in one continuous formation, which, previously to its 

 elevation and waste by denuding currents, extended from nearly 

 the eastern side of the Appalachian ch9,in, to a western margin, 

 at least as distant as the centres of the States of Ohio, Kentucky, 

 and Tennessee. 



Here then we have a coal formation, which, before its original 

 limits were reduced, measured, at a reasonable calculation, nine 

 hundred miles in length, and in some places more than two hun- 

 dred miles in breadth. I would ask, is it conceivable, that any 

 lake, bay, or estuary, could have been the receptacle of a deposit 

 so extended, or that any river or rivers could have possessed a 

 delta so vast ? The ancient Appalachian ocean grew deeper, as 

 I shall show, towards the west or northwest, and inasmuch as 

 rivers push their deltal deposits seawards, and not laterally, and 

 as the carboniferous sediments here to be described are traceable 

 coastwise, as respects this ancient sea, for a length of nine hun- 

 dred miles, it is inconceivable how any local fluviatilc cm-rents 

 could have assembled them. 



My chief object in the present memoir being to exhibit the 

 leading phenomena, which bear immediately on the discussions 

 connected with the origin of this and other coal formations, I 



