A. Winchell on the Taconic Question. 353 
the Georgia group, by Walcott. On the west side of the state 
boundary, at Bald mountain, in Washington county, and near 
Saratoga, occur fossils belonging to sub-Silurian types, and 
therefore Taconic; but the latter are found in the upper por- 
tion of the Potsdam group, and hence carr})- that group into the 
Taconic, in spite of Dr. Emmons' early opinions. It may be 
added that fossils of the same significance have been found also 
by Marcou, at Keeseville in New York ; and if the red sand- 
rock of Vermont is in continuity with the granular quartz, 
which, according to Walcott, contains primordial fossils, the 
place of the Potsdam is fixed in the Taconic. 
The discovery of sub-Silurian remains in Massachusetts, New 
Brunswick, Newfoundland, Nevada, Colorado, Mount Stephens, 
Northwest Territory [recently, by Dr. Rominger], and other 
regions in America, require no more than the mention. 
I quote a single passage from Mr. C. D. Walcott, in one of 
those careful and elaborate memoirs which have so enriched the 
literature of American geology: "Of the presence of a well- 
defined geologic system beneath the strata characterized by the 
second fauna of Barrande, or the Trenton fauna [including the 
Chazy and most of the Calciferous] of North America, on the 
North American continent, there is no question. The geologic 
sections given in this paper show it to have a total thickness of 
over 18,000 feet." ' 
It will give a clearer conception of the justness of this verdict 
of Mr. Walcott to reproduce some of the results embodied in 
his last and very important memoir,^ a continuation of which 
is promised. He gives us a colored map of the original Taconic 
region through Vermont, Massachusetts and New York. The 
so-called Georgia group, which is sub-Potsdam, is represented 
by three colors. These collectively form a band beginning at 
the northern boundary of Vermont, and extending without a 
break, through western Massachusetts to Columbia county, 
New York, where information seems to be wanting. But be- 
1 Bull. U. S. Geol. Surv. No. 30, p. 11; also Am. Jour. Sci. (3), xxxiii, 
139, Aug., 1886. 
2 Am. Jour. Sci., (3), xxxv, pp. 229-242 and pp. 307-327, with a colored 
map and a section. To be followed by a memoir on Washington county, 
N. Y. 
