C. D. Walcott — The Taconic System of Emmons. 395 



4th. — It is only a fortunate happening, and not a scientific 

 induction based on accurate stratigraphic or paleontologic 

 work, that any portion of the " Taconic System " is found to 

 be where Dr. Emmons placed it. 



5th. — The application of the principles stated at the begin- 

 ning of this paper rules out the name Taconic from geologic 

 nomenclature. 



6th. — The term Cambrian antedates Taconic for a strati- 

 graphic system and, also, as a correctly-defined faunal defini- 

 tion. 



It was stated under " Discussion " that Professor Dana held 

 the opinion that the " Lower Taconic " was the typical " Ta- 

 conic System," as first defined in 1842, but as that was proven 

 to be Lower Silurian in age, the " Taconic System " could not 

 longer be recognized.* For a time I was inclined to disagree 

 with this view, but as I approach the end of this investigation 

 I am convinced, after a full consideration of all the circum- 

 stances, that the position taken by Professor Dana is the cor- 

 rect one. 



The first published section of the " Taconic System " gives 

 all the rocks included within it in 1842.f The gneiss is rep- 

 resented on the extreme east and the u Taconic slate " on the 

 extreme west and the " shales of the Champlain group " as 

 resting unconformably on the " Taconic slate." This section 

 includes all the strata of the " Taconic System," as then known 

 to Dr. Emmons, and agrees with the description, in the accom- 

 panying text, of the rocks of the System.;}: 



Five additional sections are given on Plate XI, four of which 

 are in the typical area and agree with the section in the text 

 (loc. cit., p. 145, fig. 46). The latter section and the first four 

 sections of Plate XI do not extend west of the area of Hudson 

 slate on the line of Hoosick Falls in Rensselaer Co., N. Y. 

 (see map). They all limit the " Taconic System " at this belt 

 of the Hudson Terrane, and the accompanying text corrobo- 

 rates the view expressed in the sections. A glance at the map 

 shows that not one single outcrop of rock of the " Upper 

 Taconic " was included in the " Taconic System," as originally 

 proposed, with the exception to be noted of Section 5, Plate 

 XI, and not until 1887 was it proven that any portion of the 

 original Taconic System was older or subjacent to the horizon 

 of the Potsdam sandstone. As is mentioned in the 1st reason 

 given for rejecting the name Taconic, there is not a known 

 stratum of rock in the Taconic range that is of the geologic 



* This Journal, TIT, vol. xxxi, pp. 241-244, 1886. 

 f Geol. N. Y., pt. 2, p. 145, fig. 46, 1842. 

 % Loc. cit, pp. 144, 145. 



Am. Jour. Sci.— Third Series, Vol. XXXV, No. 209.— May, 1888. 

 24 



