SW. Ford— Western Limit of the Taconic System. 225 
Art. XXX.— On the Western Limits of the Taconic System ; 
by S. W. Forp. 
The Taconic System, asa system distinct from the Silurian, 
has appeared to me from my earliest knowledge of it, of ques- 
onable standing ; but the chances in favor of its~general ac- 
ceptance seemed to me quite as good so longas it rested within 
the limits originally assigned to it. In extending his system 
Westward, in 1846, from Petersburg, N. Y., to the Hu 
River, Dr. Emmons certainly had the remarkable uniformity of 
dip and conformability of the rocks over the region studied in 
his favor; but when he found himself under the necessity of 
assuming an inversion of the whole system in order to get the 
black slates of Bald Mountain (in which Trilobites had then 
Steater portion is still in doubt. How far the Primordial beds 
Which come up at Troy and Bald Mountain are continued east- 
ward as surface rocks, it is impossible at present to say. To 
