444 



THE AZOIC SYSTEM AND ITS SUBDIVISIONS. 



The same year Dr. Hunt further stated that the Quebec group had 

 been proved, stratigraphically ancj palseontologically, to have been de- 

 posited between the Calciferous and Chazy, Also, that this group 

 formed that part of the Appalachian region of Canada and Vermont 

 occupied by the Green Mountains and their prolongation to the south. 

 (Bull. Soc. G^ol. de France, 1867, (2) XXIV., pp. 666, 6G7.) 



Again, the Taconic Mountains and the Green Mountains were said to 

 be portions of the Lower Silurian, which had escaped erosion ; while the 

 "White Mountains of New Hampshire were said to be a detached portion 

 of the Devonian formation, the Devonian sediments having been altered 

 to gneiss and crystalline schists. {I. c, p. 687.) 



In 1869 Dr. Hunt remarked : — 



" If we look at the North American continent, we fmd along its north-east- 

 em portion evidence of great subsidence, and an accumulation of not less than 

 40,000 feet of sediment along the line of the Appalachians from the Gulf of 

 St. Lawrence southwards, during the paleozoic period, and chiefly, it would 

 appear, during its earlier and later portions The region of Lake Supe- 

 rior, where we find the early portion of the paleozoic age marked by a great 

 accumulation of sediments, comparable to that occurrljig at the same time in 

 the region of New England, and followed or accompanied by similar plutonic 

 phenomena." (Canadian Naturalist, 1869, (2) IV., pp. 395, 396 ; Smithso- 

 nian Eeport, 1869, p. 206.) 



Still later Dr. Hunt made the following statement (Am. Jour. Sci., 

 1868, (2) XLVL, p. 229,) : 



" To sum up in a few words — all the evidence, paleontological and strati- 

 graphical, as yet brought forward, affords no proof of the existence in Vermont 

 of any strata (a small spur of Laurentian excepted) lower than the Potsdam 

 formation, which the present advocates of the Taconic system regard as form- 

 ing its summit. The supposed more ancient Middle and LoM'er Taconic 

 clearly consists in part of Potsdam, in part of Utica and Hudson lliver, and in 

 part of the Quebec group, which also constitutes the Lower Taconic. To the 

 upper portion of the Quebec group, the Geological Survey of Canada have 

 already referred the gneiss of the Green mountains, assigning to this chain a 

 synclinal structure, nor does there yet seem to be any reason to believe other- 

 wise. That strata still older than the Potsdam of New York and Vermont 

 were deposited in some portions of the oceanic area, is apparent from the exist- 

 ence in New Brunswick of the St. John's slates holding a primordial fauna 

 older than the Potsdam, and it is not impossible that their equivalents may 

 underlie the Potsdam of Vermont. No such rocks have, however, as yet, been 

 detected either in Vermont or Canada, and to preserve the name of the Taconic 

 system as the designation of a series of rocks older than the Potsdam and 



