448 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



group. They certainly appear to prove unity of time and action 

 throughout this great length of country, — the time being that of the 

 post-carboniferous uplift. I have collected them together for that 

 purpose. 



1st. The general conformation of the disturbed region across its 

 whole breadth is the same. The Appalachian ridges are long, 

 narrow, and steep, with even summits and remarkable parallelism. 

 Many of them are almost perfectly straight for more than fifty miles. 

 Some of their groups are curved ; but the outlines of all are marked 

 by gentle transitions and an astonishing degree of regularity (H. D. 

 Rogers, Trans. Assoc. Am. Geol. 1842, p. 475). 



2nd. The movement of elevation, folding, fracture, and metamor- 

 phism affected the Coal-measures equally with all the other strata in 

 and about the Appalachian ridges. The strikes and dips of all the 

 gneiss, slates, and marbles, and of all the unchanged fossiliferous rocks, 

 are clearly continuous into or from the coal, according to the end of 

 the series at which we begin. Professor Rogers (Trans, p. 522) 

 says, " Excepting in one or two localities, the Appalachian formations 

 constitute one unbroken succession of conforming strata, from the 

 lowest members of the system, which repose immediately on the 

 primary or metamorphic rocks, to the highest of the carboniferous 

 strata ; we must therefore conclude that the elevatory action could 

 not have begun, at least with any degree of intensity, until the 

 completion of the carboniferous formation," but immediately after- 

 wards. 



In proof of this I appeal to the most beautiful exhibition of geo- 

 logical arrangement on record, that of Pennsylvania, laid down by 

 the brothers Rogers, and, by their generous permission, placed on 

 the map before you little more than a year ago, 



It has been the enviable privilege of these distinguished observers 

 to indicate to their fellow-men the grand conceptions and exquisite 

 order that have hitherto lain hid in these mountain-recesses. 



The map shows that every individual stratum, throughout the long 

 palaeozoic succession, stands in its proper stratigraphical relation, 

 with its strike running north-east, or varying with the great central 

 axes of the crust-ruptures from Alabama to Canada : imperfectly 

 represented on my map by a broad white line. 



On a branch of the River Juniata, fifteen miles south of Hunting- 

 don, Pennsylvania, the high contours of the country expose a solitary 

 oblong mass of coal-measures (ten to twelve miles long), thirty miles 

 to the east of any of its carbonaceous contemporaries. It is curious 

 to remark its near parallelism to the central axes (thirty miles east), 

 and to notice how it is based upon, and surrounded by, the usual 

 suite of sedimentary rocks downwards. 



3rd. According to Rogers (Trans, p. 490), "Every section of the 

 Appalachian chain, whatever its direction or curvature, offers the same 

 remarkable and beautiful features and gradations in its axes ; imply- 

 ing that the cause of these phsenomena was some grand and simple 

 energy co-extensive with the whole margin of the Appalachian Sea 

 from Canada to Alabama." 



