436 Section of the Alleghany Mountain, ^c. 



is fifty to one hundred feet thick. Large displaced fragments 

 cover the surface, and have even been transported several miles 

 in abundance, to the bottom of Bald Eagle valley, many hun- 

 dred feet below. We occasionally see this breccia disintegrated, 

 its pebbles occurring loosely, in the form of gravel, in extensive 

 beds. In its compact state, this rock is sought for the purpose 

 of fire or hearth-stone, for the neighbouring iron works. The 

 position occupied by the conglomerate, is sometimes conspicuous, 

 in its lofty site, at the distance of several miles ; and in those 

 cases, it appears as a bare and steep ledge, on the eastern slope 

 of the Alleghany mountain ; pursuing its course parallel with the 

 summit, and commonly from one hundred to three hundred feet 

 below the crest. In winter, when all other parts of the moun- 

 tain are enveloped in snow, this dark ledge of gritstone is singu- 

 larly discernible, forming the most striking exception to the 

 general remark I have previously made. Its presence is no 

 less distinguished by the change in vegetation, above the limits 

 of this parallel. From the valleys, (which are occupied by 

 hemlocks, white pines, and other dark evergreens,) white oaks, 

 and some other deciduous trees, ascend upwards, to the base of 

 the conglomerate, and are then succeeded by red, or pitch pines, 

 whose dark foliage, and stunted forms, arise amidst a thick 

 brushwood of chestnuts, forming those wild and w^orthless tracks, 

 called barrens.* These upper strata consist of sand and beds 

 of soft, white, porous, sandstone. The aggregate thickness of 

 the beds above the limestone, up to this point, can scarcely be 

 less than 1600 or 1800 feet. This estimate, of course, must be 

 received as an approximation, the accuracy of which, is mate- 

 rially influenced by the inclination of the lower members of the 

 series. 



Descending from the sterile region above the conglomerate, 

 we now perceive, in the sandstone which succeed, innumerable 

 proofs that we have entered the limits of the great central coal- 

 field. The first vein of bituminous coal is here discovered at an 

 elevation, only one hundred and fifty feet below the crest of the 



* It may be observed, that, in these mountainous regions, the season of winter and snow 

 is, in some respects, particularly favourable to the display of its broader and most charac- 

 teristic geological features, which are commonly obscured, at other times, by a luxuriant 

 forest vegetation. At no time or place have I seen geological changes more distinctly 

 indicated, or more influential on the character of the scenery, when viewed from great 

 distances. 



