Remarks on the Coal Formation of Pennsylvania. 345 



Shaver's mountain by day light, I am able to say that its structure re- 

 sembles that of the Savage to near its top. 



The location of the road reflects great credit on the engineers ; 

 the contour is admirable, and must be highly valued by geologists, 

 as it presents a profile section across the whole range, clinging on one 

 side to the mountains, that, in some places, seem to lower miles above 

 and so near loalls, formed by the cut, that the carriage wheels often 

 graze them ; and on the other, a precipice almost perpendicular, 

 leading to a gulf below that the eye cannot fathom. The sand- 

 stone strata which are almost constantly in sight from the base of 

 Shavers to near the greatest altitude of the Savage, inchne 15° or 

 20°, as well as I could judge in passing rapidly — the dip opposite the 

 setting sun in the middle of November. From thence it declines by 

 gradations hardly perceptible to near the western base, and there be- 

 comes horizontal, like all the strata far beyond the Ohio. 



There are several varieties of sandstone ; the most common has a 

 yellow or ferruginous tinge, — the layers are of sufficient thickness for 

 all the masonry on the whole line of road, and for this purpose it 

 has been used in the numerous bridges, culverts and embankments, 

 which are constructed with skill ; but the cement has entirely failed, 

 owing probably to substituting loam for sand, which appears to be rare 

 in these regions ; I have never been able to discover a pebble, or a 

 handful of silex except in the beds of water courses, or that which 

 is coherent in the sandstone, on any of these mountains, — the soil 

 being a fine friable loam. The parapet walls of all these construc- 

 tions exhibit a mortifying appearance of dilapidation, they are all fast 

 crumbling, some already even with the pavement, and fatal accidents 

 may soon be expected to follow.* 



In many cuts on the Savage, the sides next the mountains present 

 a mural front of sandstone, in layers resembling regular masonry ; 

 reminding one of those Vvfalls described by Lewis and Clarke on their 

 route to the Rocky Mountains, although upon a much smaller scale. 

 On the principal elevation, I observed extensive patches of the surface 



* Cannot the want of sand be supplied by heating the sandstone itself red hot, 

 by piles of brushwood, and then throwing the fragments into cold water, or sprink- 

 ling it upon them ? A few strokes of the stone hamner would then, probably reduce 

 them to grains or fragments, sufficiently fine for mortar ; this suggestion is made 

 upon the supposition that the sandstone is siliceous, of which the observations of Mr, 

 Pomeroy can leave no doubt ; as silex is indispensable in mortar, it would justify, in 

 this case, even a heavy expenditure in transporting sand and gravel, from a distance, 

 provided it can be obtained in no other way. — Ed. 



Vol. XXL— No. 2. 45 



