226 DR. THOMAS STERRY HUNT ON THE 
§ 22. By Prof. H. D. Rogers, and his assistants on the first geological survey of Penn- 
sylvania, the series of rocks found in the two regions just mentioned underlying the sand- 
stone, No. IV., were regarded as stratigraphically equivalent. He rightly identified the 
fossiliferous shales and limestones which, in the central valleys, immediately underlie this 
sandstone, with the Loraine, Utica and Trenton divisions of the Champlain series of New 
York, which in his nomenclature included three great divisions: I. Primal; II. Auroral; 
III. Matinal ; the first. or silicious corresponding to the Potsdam; the second or calcareous 
to the Calciferous, Chazy and Trenton ; and the third or argillaceous to the Utica and Loraine. 
This correlation, for the Trenton, Utica and Loraine, was established by Rogers, alike on 
stratigraphical and paleontological grounds, for the central valleys. The rocks of the great 
south-eastern or Appalachian valley, which were seen to be in many respects unlike the 
preceding, were spoken of by Rogers as belonging to a distinct or “south-eastern type” of 
the same Primal, Auroral and Matinal series. Herein, Rogers adopted the view of 
Mather, who, as we have seen, (§ 11) had already declared these same rocks, in their exten- 
sion to the north-eastward, to be nothing more nor less than modified representatives of 
the members of the Champlain series. In accordance with this view, Rogers called the 
quartzites and schists of the great valley, Primal, the granular limestones or marbles 
Auroral, and the overlying schists and argillites, Matinal. Very great differences both in 
thickness and in lithological characters, exist between this series and the Champlain 
division in northern New York and central Canada; but the rocks in question lie, in both 
cases, between two well-defined geological horizons, having the ancient gneiss below, and 
the Oneida, called by Rogers the Levant sandstone (which was No. IV in his notation) 
above ; and in both cases they present the same three-fold division of silicious, calcareous 
and argillaceous strata. 
§ 23. In support of the parallelism thus suggested, it was said that the peculiar 
markings to which the name of Scolithus linearis had been given—and which are character- 
istic of the basal or Taconic quartzite alike in Pennsylvania and in Massachusetts—were _ 
identical with a form found in the typical Potsdam sandstone of New York and Canada. 
The Potsdam form of Scolithus, however, as I have elsewhere shown, is very distinct, 
and does not resemble the Scolithus of the Taconic quartzite so much as it does the similar 
form found in the Medina sandstone.* 
§ 24. There is, in fact, up to this time, no evidence that the typical Potsdam sandstone 
and Calciferous sandrock of northern New York exist in eastern Pennsylvania ; but on the 

contrary there are many reasons for supposing that in this region, as in eastern Canada, 
and along the eastern side of the Champlain and Hudson-River valleys, the period of 
these two sub-divisions of the New York system is represented by the First Graywacke of 
Eaton, the Upper Taconic of Emmons; which, as will be shown farther on, is now recog- 
nized as contemporaneous with the typical Potsdam and Calciferous sub-divisions. Rocks 
supposed to represent this graywacke-series are found in the great valley of Pennsyl- … 
vania, and these, together with the divisions immediately preceeding them ; namely, the 
Primitive Quartz-rock, the Primitive Lime-rock, and the Transition Argillite ;—which 
constitute the Lower Taconic of Emmons,—are, as we shall endeayor to show, represented 
by the Primal, Auroral and Matinal of the south-eastern area. : 


* Azoic Rocks, pp. 135-139. 

