138 DR THOMAS STEEEY ÏÏUIST ON THE 



devised at a time wheu the progress of geology in New York had made known, in the 

 northern district of that state, a great series of nearly horizontal fossiliferous strata resting 

 upon the upturned granitoid gneiss of the Adirondacks and including the now well- 

 known subdivisions of the paleozoic, from the Potsdam sandstone upwards. The relations 

 tions and succession of these various rocks were simple and evident. To the east and south- 

 east of this region, however, beyond Lake Champlain and the. Hudson Eiver, there were 

 found other crystalline rocks unlike the ancient gneiss, and other uncrystalline sediments 

 very different in physical character and in stratigraphical attitude from the paleozoic strata 

 of the northern district of New York. The question then arose as to the correlation of 

 these unlike rocks in the two regions. Amos Eaton, by a grand generalization, had al- 

 ready arrived at a system of classification in which he recognized the existence in the 

 eastern or Appalachian region, of types of Primitive crystalline rocks other than the granit- 

 oid gneiss, and of gi-eat masses of sedimentary strata to which nothing similar was found 

 in the contemporary series in the Adirondack region. 



§ 169. Rejecting the teachings of Eaton, and falling back on the metamorphic doctrine 

 which was then so generally received, Mather maintained, in 1843, that whatever to the 

 east of the Hudson differed lithologically from the ancient gneiss on the one hand, and 

 from the paleozoic rocks of New York system, as seen in the Adirondack region, on the 

 other, could be nothing else than these same paleozoic rocks folded and subjected to 

 successive stages of so-called metamorphism, as seen in the Lower Taconic c[uartzites and 

 marbles and the crystalline schists which accompany them, as well as those others that 

 succeed them farther to the east. All of these were, according to Mather, nothing but 

 the more or less altered equivalents of the members of the New York system, from the 

 Potsdam sandstone to the Loraine shales, both inclusive ; while the great Gray wacke belt, 

 extending along the east side of the Hudson from Duchess County northward through 

 Vermont, was not, as maintained by Eaton, older than the Trenton limestone, but newer 

 than the Loraine shales. 



§ 1*70. The considerations which lent probability to this scheme were, first, the gen- 

 eral resemblance of this Grraywacke series to the Oneida, Clinton, and Medina subdivisions 

 of the New York system, to which it was by Mather referred ; and secondly, the fact that 

 the argillites with unctuous schists, granular limestones and granular quartzite, which he 

 agreed with Eaton and Emmons in placing below the adjacent Gray wacke, presented a 

 certain resemblance to the Loraine and Utica shales, the Trenton and Chazy limestones, 

 the so-called Calciferous sand-rock, and the underlying Potsdam sandstone. This general 

 parallelism from the top of the Graywacke downward, which suggested to the mind of 

 Eaton only the great law of cycles in sedimentation (since generally recognized), was 

 accepted by H. D. Rogers and by Mather as a proof of identify. In fact the Lower Taconic, 

 as seen along the Appalachian region, in its regular succession of granular quartzites, 

 with granular limestones and intervening and overlying soft schists and argillites, presents, 

 notwithstanding its many mineralogical differences, its crystalline character, and its great 

 thickness, that general parallelism to the Champlain division which is so often remarked 

 in groups of sedimentary strata at A^ery various geological horizons. It is thus, in certain 

 respects, more like the Adirondack Cambrian and Ordovician, with which it has been 

 confounded, than their Appalachian representatives. These resemblances were coupled 

 with the fact that along the base of the South Mountain, in Pennsylvania, this succession 



