252 DR. THOMAS STERRY HUNT ON THE 
stratigraphical geology, not the breaks dividing groups from each other, so much as the 
beds of passage which serve to unite all these groups in one great system.” 
V.—TuHeE UPPER Taconic OR FIRST GRAYWACKE. 
§93. We now return to the history of the First Graywacke which, as has been shown, 
was, by Mather, in 1842, assigned, contrary to Eaton’s conclusion, to a horizon above the 
Trenton limestone, and to the position of the Second Graywacke of the latter. This view 
was for a time accepted by Emmons, but was, from the first, not satisfactory to him, and 
gave rise to doubts and perplexities which, as I have elsewhere shown, are reflected in 
portions of his report on the geology of the Northern district of New York, published at that 
date. Mather then regarded the Taconic quartzite, limestone and slates of Emmons as 
forming one continuous series with the succeeding First Graywacke of Eaton, and referred 
the whole to the various sub-divisions of the New York system from the Potsdam to the 
Medina, both included. 
$94. In 1846, in his report on The Agriculture of New York, Emmons returned to the 
view of his former master, Eaton, assiging the First Graywacke to a position below the 
Trenton limestone, and immediately above the Transition Argillite. He now proposed to 
regard it as an upper member of the Taconic, and included it under the general name 
of Taconic slates. The rocks to which the name of Taconic had been restricted in 1842, 
consisting of Haton’s three divisions of quartzite, limestone and argillite, were, however, 
still held by Emmons to be older than the base of the Champlain division ; while the suc- 
ceeding graywacke was itself regarded as belonging to the lower part of this division, and 
as a thickened and modified form of the Calciferous Sand-rock ; which, in its eastward 
extension, was said to include a great variety of rocks, and to be “ protean ” in its characters. 
The Potsdam sandstone was then supposed by Emmons to be wanting in this eastern 
region, but he was afterwards led to regard certain strata in western Vermont as its 
representative. 
§ 95. In 1855, returning to the subject in his treatise entitled American Geology, Emmons, 
while still adhering to the views of its age and relations announced by him in 1846, 
proposed to consider the Taconic system as consisting of two parts, between which, 
according to him, “ the line of demarkation is tolerably well defined.” Of these, the lower 
division, or Lower Taconic, corresponded to the Taconic series as first proposed in 1842; 
and the upper division, or Upper Taconic, to the First Graywacke. The same view is 
farther set forth in his Manual of Geology, in 1860, and in his subsequent reports on the 
geology of North Carolina. The action of Emmons, in thus uniting the First Graywacke 

recalling some sponges. These, like the tubes, were filled with calcite, agate or crystalline quartz, and sometimes 
in part with a greenish chloritic mineral, apparently delessite.” 
Whether the crystalline silicated rocks, which make up the larger part of this vast series, are of plutonic 
origin, as is generally assumed, or,as maintained by Rivot in 1856, have had a neptunian origin similar to that of 
the silicated rocks of the older series, is a question yet to be discussed. (Ann. des Mines [5] x., pp. 441-445.) As 
regards their geological horizon, it must be said that whether the Animikie, which we have compared with the 
Taconian (supra, 4 89) is, as supposed by Logan and Irving, older, or as conjectured by Macfarlane, newer than 
the Keweenian, it is evident that both of these are separated by a period of wide-spread disturbance, and great 
subsequent erosion, from the horizontal Lower Cambrian sandstones of the region, which overlie them both 
uncomformably. 

