reiry.] 352 [December 18, 



cliavactcrif^tic fossils are more carefully examined and minutely 

 stuilied, witiial more critically compared and thus better known, 

 especiiilly in the grand type-features by which tliey are resj^ectively 

 di.<tiaguishe(l. 



These fects accoi'dingly seem to indicate that the Potsdam Sand- 

 stone is not correctly described, and cannot be properly viewed, as 

 the lowest, or as a lower, member of the second great group of fos- 

 siliferous strata; that, of good right, it should be regarded as the 

 summit, or crowning portion, of the primordial sericK; and that thus 

 the Calciferous formation both presents itself in nature, and in conse- 

 quence imperatively claims recognition, as the base of the Champlain, 

 or Lower Silurian, system of rocks. Such a division between the 

 primordial life-period, and the great one that follows it, is certainly 

 suggested by what is thus far known of the formations; and, if facts 

 prove it to be what it ajDjJcars, it ought surely to be acknowledged 

 and adopted, both as tending to make our classification more simple 

 and exact, and as helping to render the relations of these two exten- 

 sive series of sedimentary beds — at once amongst themselves and to 

 each other — more distinct and easy of* comprehension. 



Having thus cursorily surveyed the Red Sandstone of Vermont, as 

 it is in itself and in its more general relations, I will close this paper 

 with a brief synopsis of the two great systems of rocks Avhich have' 

 been under revicAv. Reading from below upward, we have : — 



{3. Upper : — Bh-rlseye Limestone, Black River, and Trenton, 

 Utica Slate, and Lorraine Shale. 

 2. jMiddle: — Chazy Limestone, in its several divisions. 

 1. Lower: — Calciferous Sandrock, in its several divisions. 



(3. Upper: — Potsdam Sandstone, iu its several divisions, 

 j 2. Middle:— Black and Brown Slates, with Limestones and 

 L Taconic. -^ Sandstones. 



I 1. Lower: — Talcose and Talcoid Slates, with Limestones and 

 (_ Quartzites (or Conglomerates). 



The above is given, as the^ most satisfactory general view, that I 

 have been able, up to this time, to get of these rocks, after a long 

 study of them in the field. And it is presented, Avithout details, and 

 by no means as an ultimatum, but sim^jly as an essay toward the solu- 

 tion of some of the manifold difficulties involved in one of the most 

 intricate and jierplexing sections of the Geologic Record ; presented 

 with diffidence, and still with unwavering confidence in the truth of 

 nature; presented in the hope that new light maybe elicited; that 

 old errors, so far as they exist, may be discarded ; and that thus a 

 more consistent understanding of these formations may be at last 

 secured. 



In this summary, the terms "Taconic" and "Champlain" are used, 

 not as implying any theory, but because they are familiar and local. 



