278 J. D. Dana on the Quartzite, Limestone, ete. 
At the same time I inclined toward the views of Profs. Rogers 
and Prof. Hall because of my confidence in them as geological 
observers. When, thirteen years since, Sir Wm. Logan, after in- 
vestigations in the Green Mountains of Vermont and Massachu- 
setts, as well as in Canada, brought out his view that the Taconic 
rocks—those of Taconic mountains and the associated limestone 
—were identical with the Quebee group,* (an opinion then partici- 
pated in, I believe, by Prof. Hall,) I gave it acceptance and 
adopted it inmy Manual of Geology. Within the past halfa dozen 
years I have looked to the rocks themselves in order to obtain 
ground for an independent judgment; and the result is that 
above presented, It makes the Taconic rocks and the associated 
limestone one in formation, as held by Logan; and it differs from 
his view as to the age of the beds—on the basis partly of the 
older examination of fossils by Hall, and especially on the recent, 
by Billings ; and diverges also as regards the relations of the 
quartzite. 
The conclusion I have presented relates to the original Taconic 
as presented by Emmons in his New York Geological Report 
published (in quarto) in 1842, and not to the unfortunate addi- 
tions to it made in his later publications+—unfortunate because 
they drew off atsention from the real Taconic, and became the 
chief subjects of controversy and prolific sources of error. 
the quartzite contains no ches of gneiss or of any 0 the 
* The views of Logan are to be found in thi i ; and 
. na s Journal, Il, xxxi, 210, 1861; a0 
cers pages ace conclusions, by T. Sterry Hunt, at page 392 of the same 
an article entitled “On some points i i logy.” : 
+ See this Ja TIL, iii, 468. points in American Geology: 
