TACONIC QUESTION INIGEOLOGY. 1S9 



is found lying between the ancient granitoid gneiss beneath, and the Oneida sandstone 

 above, precisely as the Potsdam-Loraine succession in northern New York intervenes bet- 

 ween the same gneiss and the same sandstone. 



§ 1*71. It was not, therefore, surprising, that the geologists then engaged in the study 

 of Pennsylvania, New Jersey, and southern New York, should have accepted this plausible 

 and, at first sight, natural explanation of the apparent lithological parallelism presented 

 between these regions and northern New York, or that Mather endeavored to extend it to 

 the rocks east of the Hudson. This attempt led him to assign to the great Graywacke 

 series, which we now know to be of Cambrian age, a position above the Loraine shales, 

 or, in other words, to confound it with the Oneida, Medina and Clinton subdivisions of 

 northern New York and of Pennsylvania, and thus to mistake the First for the Second 

 Graywacke of Eaton, and, in fact, to deny the existence of the former as a great series 

 lying above the Lower Taconic and below the horizon of the Trenton limestone. The 

 brothers Rogers and Mather, forty years since, reasoning from the paleozoic succession as 

 displayed in the Adirondack area, were not prepared to admit that, in a region so near as the 

 great Appalachian valley, the paleozoic sediments beneath the Trenton horizon could as- 

 sume a type so unlike the well-known Potsdam and Calciferous subdivisions of the north- 

 ern district of New York, or that these subdivisions could be represented in the Appa- 

 lachian area by the vast and lithologically unlike series of the First Graywacke, which 

 Eaton had already, ten years before, assigned to its true position below the horizon of the 

 Trenton limestone. Hence came the great mistake in American stratigraphy, the denial 

 by Mather and his followers of the distinctness of the First Graywacke of Eaton, and the 

 assertion of its identity with the Second Graywacke of the same author. So long as this 

 false position was maintained, there was a plausible argument to be made for the original 

 hypothesis of the brothers Rogers and Mather as to the age of the Lower Taconic series ; 

 but with the recognition of the correctness of Eaton's view of the First Graywacke, the 

 fallacy of this hypothesis became obvious, and those who would still advocate it can only 

 do so by ignoring alike the results of stratigraphical and paleontological study for the last 

 generation. 



§ 1*72. The absence from the granular quartz-rock, the granular marbles and their in- 

 tercalated and conformably overlying schists and argillites of the Lower Taconic series, of 

 the organic remains of the various members of the Champlain division, or, indeed, of any 

 organic form save the peculiar Scolithus of the granular quartz-rock already noticed, 

 (§ 23) was explained by those who maintained the i)aleozoic age of the series by the con- 

 venient hypothesis of a chemical change, attended by crystallization or so-called meta- 

 morphism, which was supposed to have effaced the original characters of the sediments 

 and obliterated their organic remains. In accordance with this hypothesis, it was believed 

 that great series of strata might, within short distances, assume a new aspect, not 

 through any original differences in the sediments, but from transformations wrought in 

 these after deposition, in virtue of which, fossiliferous and earthy limestones, losing all 

 traces of their organic remains, could be converted into granular limestones containing, 

 instead, only crystalline silicates, while ordinary sandstones and argillites might become 

 micaceous, chloritic, or hornblendic schists, and even gneisses and granite-like rocks. 



§ 173. These views, a development of the Huttonian school in geology, were, as is 

 well known to students, accepted a generation since by a large number of geologists, both 



