312 CD. Walcott — The Taconic System of Emmons. 



In 1359 the section is republished,* but the numbers are 

 omitted from all the formations except those of Gray lock Peak. 

 "Whether the omission was by design or accident is unknown. 



In the black slates, at the summit of the " Taconic System " of 

 1844-'47 and at the base of the "Upper Taconic" of 1856, 

 Dr. Asa Fitch found a few fossils which he gave to Dr. Em- 

 mons, who described two species in the memoir of 1844— '47, 

 under the names of Elliptocephala asaphoides and Atops tri- 

 lineatus. In 1859 Dr. Emmons compared these fossils with the 

 Primordial fauna of Barraude, and established their position in 

 the stratigraphic series on paleontologic evidence, f Their ref- 

 erence to a pre-Potsdam horizon, in 1844-'47 and 1856, was on 

 the supposed stratigraphic position of the beds in which they 

 occurred. 



Resume. — It is not necessary to repeat the full and accurate 

 lithologic descriptions of the five terranes (fig. 10) mentioned 

 by Dr. Emmons in 1844-'47 and 1856. They are grouped in 

 fig. 10 to represent his view of their succession within the 

 " Taconic System." 



2. Stratigraphic position of the " Taconic System" — Dr. 

 Emmons founded the " Taconic System " under the belief that 

 it was composed of older formations than those of the New 

 York Lower Silurian, the base of which was then the well- 

 known Potsdam sandstone. In the memoir of 1842, he says : 

 " But I have, at the head of this section, asserted that the 

 slates and masses of the Taconic System are not related to, or 

 connected with those of the Champlain group. By this I mean 

 that they are not the same rocks in another condition." \ 

 Again he says : " They are to be considered, however, as fur- 

 nishing us with a knowledge of that state which immediately 

 preceded the existence of organic beings." § After further field 

 study his views became more positive in regard to the relation 

 of the Taconic to the Lower Silurian rocks. He says : " I shall 

 take the broad and distinct ground that the Taconic System oc- 

 cupies a position inferior to the Champlain division of the 

 New York system, or the Lower division of the Silurian system 

 of Mr. Murchison." | 



" 1. Position. — It rests unconformably upon primary schists, 

 and passes beneath the New York system, the oldest and infe- 

 rior members of the latter being superimposed unconformably 

 upon the Taconic slate." f" These views were sustained in his 

 publications of 1856, 1859 and 1860. 



On the section, accompanying the memoir of 1844-'47, pi. 

 18, Section I, the strata of the " Taconic System " all dip con- 



* Manual of Geology, p. 85, fig. 60. f Manual of Geology, p. 87, 1859. 



{Geol. N. Y.,pt. 2, p. 138, 1842. § Loc. cit„ p. 164. 



|| Agric N. T., vol. i, p. 55, 1847. fLoc. cit., p. 108. 



