136 DE. THOMAS STEREY HUNT ON THE 



Cambrian G-raywackc of Eatou and the Upper Taconic of Emmons, as shown in the 

 table, § 18. (Eaton, Emmons, Perry, Marcou.) 



II. That, although lying beneath the greater part of this Graywacke series, they 

 are not distinct therefrom, but are the altered representative of the Levis limestone or 

 Sparry lime-rock, imagined by Logan to lie between the Red Saud-rock below and the chief 

 part of the Quebec group above. (Logan, in his geological map of 1866.) 



III. That they are the altered representatives of the whole of the limestones which, in 

 the New York system as seen in the Adirondack area, appear between the Potsdam sand- 

 stone and the Utica slate. (Mather, H. D. and W. B. Rogers, J. D. Dana.) 



IV. Allied to the last is the view expressed by Wing, in 18*75, that they include the 

 representatives of the limestones of the Potsdam and Quebec groups of Logan, together 

 with the Trenton and the Loraine or Hudson River group, or, in other words, the whole 

 of the Champlain division of the New York system, fi'om the Potsdam to the base of the 

 Oneida. 



V. That they belong to a horizon above the Champlain division, and are true Silurian 

 and Devonian. (C. B. Adams, Ed. Hitchcock, W. B. Rogers.) 



§ 163. We have already briefly set forth the arguments on which these various and 

 contradictory hypotheses have been based. While the fifth supposes the Lower Taconic 

 limestone to hold a position above the Oneida sandstone, and consequently superior to the 

 Second Graywacke, the third was devised at a time before the existence of the First Gray- 

 wacke, (maintained by Eaton and Emmons, but denied by Mather,) hadbeen again brought 

 into favor by the conversion of Logan to the teaching of Emmons, and by his farther admis- 

 sion that the Lower Taconic limestones in Vermont and Massachusetts are inferior to a 

 great mass of sandstones, conglomerates and shales many thousand feet in thickness, con- 

 stituting what he called the Lauzon and Sillery divisions of the Quebec group. 



§ 164. It was not until after his change of view as to the geological horizon of this 

 great sedimentary or Graywacke series, or in other words, after he had recognized the fact 

 that its place was below and not above the Trenton limestone, that Logan began to ex- 

 amine the Lower Taconic rocks in western New England. Having then, by a misconcep- 

 tion, placed the Levis or Sparry lime-rock at the base instead of the summit of the Gray- 

 wacke, and still holding to the notion of Mather that the crystalline rocks along the 

 eastern border of the great Appalachian valley were but a portion of the paleozoic strata 

 in a so-called metamorphic condition, Logan was led to look ujîon the Lower Taconic 

 limestone as an altered representative of the Levis limestone, and its underlying quartzite 

 as Potsdam ; the immediately overlying schists and the succeeding sandstones, con- 

 glomerates and shales of the Graywacke series being referred to the Lauzon and Sillery 

 divisions of his Quebec group. Hence the wide difference between the view of Logan, 

 given under II, and that of Mather and his followers, which we have numbered III. 

 While both would place the Lower Taconic limestones above the Potsdam and 

 below the Oneida, Mather imagined the plates and sandstones overlying them to be 

 Ordoviciau and Silurian (that is, TJtica, Loraine and Oneida) or the Second Graywacke of 

 Eaton. Logan, on the other hand, conceiA^ed the same overlying beds, as seen by him in 

 Vermont, Massachusetts and New York, to belong to the Cambrian or First Graywacke. 

 The error of Mather and of H. D. Rogers was that both failed to recognize this great series 

 of sandstones, conglomerates and slates, which are so conspicuous in the Appalachian 



