1887] The Taconic Question Restated. 241 
that in this Taconic slate group—described in 1842 as “ often 
becoming a coarse graywacke” and now called “ protean”—are 
numerous subordinate divisions, among which he mentions coarse 
greenish sandstones, gray sandstones, red and chocolate-colored 
shales, roofing-slates, green and black flinty slates, blue compact 
limestones, and gray silicious limestones, all of which are in- 
cluded in this great disturbed and faulted belt of uncrystalline 
strata. One of these subdivisions he described as a black slate 
with trilobites, and noticed another containing impressions re- 
sembling graptolites. In further proof of the fossiliferous char- 
acter of this great Taconic slate group, which he had already, in 
` 1842, referred to “the lower part of the Silurian system,” he de- 
clared that besides these in the black slates just mentioned he 
had found fossils in the green sandstones and the green slates; 
while with regard to the Sparry limestones he remarks that “ no 
fossils have yet been discovered in this rock, though it must be 
confessed sufficient examination has not yet been made for mi- 
croscopic bivalves.” 
§ 18, It is here important to remark that the term “ Taconic 
slate” applied to this upper and notably fossiliferous portion of 
the Taconic system of Emmons has led to the erroneous opinion 
that it is in some special sense the representative of the system, 
and to look upon the lower members as of less significance; a 
view which, it is unnecessary to say, finds no countenance in 
the publications of Emmons. Eaton, as we have seen, asserted 
the existence of a stratigraphical break between the Taconic slate, 
his First Graywacke, and the underlying Transition Argillite. 
This upper unconformable portion was afterwards separated by 
Emmons from the inferior members of the system, and designated 
Upper Taconic. In his “ American Geology,” in 1855, he in fact 
proposed to consider the Taconic system as consisting of two 
parts, between which, according to him, “the line of demarcation 
is tolerably well defined.” Of these, the lower part, henceforth 
called by him Lower Taconic, included (1) the Primitive Quartz- 
rock, (2) the Primitive Lime-rock, or Stockbridge limestone, and 
(3) the Transition Argillite, or Magnesian slate, with the lower 
roofing-slates. The Upper Taconic included the great group of 
the First Graywacke, called by Emmons, in 1842 and 1844, the 
Taconic slates, with the Sparry Lime-rock, called by him the 
Sparry limestone. This same view is again set forth by Emmons, 
