412 J. D. Dana — Brief history of Taconic ideas. 



As late, then, as February, 1841; there was no indication 

 that the Taconic system had taken shape in the mind of Prof. 

 Emmons, although pretty well stored with Taconic facts. In 

 opposition to the ideas of the Taconic system of 1842, the 

 quartzyte is spoken of as the " Potsdam sandstone " in a meta- 

 morphic state, and the associated granular limestone as of " the 

 same geological epoch." 



In 1842, the quarto Eeport on New York G-eology by Prof. 

 Emmons appeared, with its letter of transmittal dated January 

 1, 1842 ; and in this volume the account of the Taconic system 

 as a new system of rocks in American geology covers pages 

 135 to 164, thirty quarto pages. The germinant period was, 

 consequently, between February 1, 1841, and January 1, 1842. 



Another fact brings us closer to the time of first announce- 

 ment. The system became a subject of special discussion, as I 

 am told by Prof. James Hall, at the meeting of the American 

 Association of Geologists and Naturalists held early in April, 

 1841, at Philadelphia. This narrows down the germinating 

 period to the two months between February 1 and April 10 of 

 1841. 



Those who took a prominent part in this first discussion 

 were Professors Henry D. Rogers, Edward Hitchcock, Vm. 

 W. Mather, Mr. James Hall and Mr. Lardner Yanuxem. Prof. 

 Rogers was interested in the subject because of his elaborate 

 geological study of the Appalachian Mountain system on which 

 he reported at length to the Association the following year ; 

 Prof. Hitchcock, because the heart of the Taconic region was 

 within his own field of study — the state of Massachusetts, — his 

 final report on which he already had in the press ; Prof. 

 Mather, because part of the Taconic rocks west of Massachu- 

 setts were very largely within his section- of the survey of the 

 State of New York ; Prof. Hall, because of the bearing of the 

 facts on the system of New York rocks. Prof. Yanuxem, also 

 one of the New York State geologists, had under his charge 

 only southern New York west of the Taconic area and had 

 given the rocks no study. 



Although we have no report of the discussions,* we learn 

 from later publications that Professors Hitchcock, Rogers, 

 Hall and Mather objected to the views of Prof. Emmons, and 

 Mr. Yanuxem f favored them. 



* The Proceedings of the meeting in this Journal, xli, 158, 1841, and in the 

 Trans. Assoc. Am, Geol. and Nat., 1840-42, contain no allusion to the discussion, 

 discussions being, as the Preface of the Transactions states, " imperfectly reported 

 in these pages." The only fact of any Taconic interest meutioned in the Proceed- 

 ings of the meeting for 1841 (Proc. Assoc, 1883, p. 16, and this J., xli, 163), is that 

 of the occurrence of impressions of Annelids in the slate of Waterville, Me., by 

 Prof. 0. P. Hubbard — the fossils and slates being afterward (1844) claimed for the 

 Taconic by Emmons. Prof. Wm. B. Rogers did not become a member until 1842. 



f Mr. Vanuxem has a page on the subject in his N. Y. Geological Report, p. 22. 



