882 J. D. Dana—Hudson River Age of the Taconic Schists. 
I have been again over the Ancram region, but without finding 
other specimens—the limestone being much: more crystalline 
than it is toward Poughkeepsie. 
The fossils of Pleasant Valley and Rochdale, prove that the 
limestone of Wappinger Creek Valley contains a stratum of the 
age of the Trenton; and that of Ancram has the same bearing. 
The width of the part of the belt at the two former places 
is two-thirds to three-fourths of a mile; and since the be 
containing the fossils is, at each of these localities, within 200 
to 230 yards of the eastern margin of the limestone belt, it is 
probably one and the same bed. The lithological character 
of the rock sustains this. The western margin lies conformably 
against the Poughkeepsie ‘Hudson River” slate; and hence the 
a. western portion also must bé Trenton. 
It follows then: first, that the belt is an 
anticlinal of limestone (as represented in 
the figure, f, toward the east side, being 
_. the observed fossiliferous bed); and, sec- 
\ ondly, that the slate on the east of it is of 
\\Y Hudson River age, as well as that west. 
Further: these facts, and the concurring 
evidence from Ancram, where the lime- 
stone is essentially the Copake limestone, 
leave little doubt that Trenton beds continue northward to the 
very foot of the Taconic Mountains; and that the schists of the 
Taconic Mountains, like those of either side of the Wappinger 
Valley, including Winchell’s Mountain, are Hudson River in 
age. 
The Wappinger Valley belt may have at centre a Chazy or 
other subjacent limestone stratum; and if so, the fact would 
only make more complete the identity of the Poughkeepsie 
and Vermont formations. 
n the vicinity of Stissing Mountain there are quartzyte out- 
crops ; and, if the rock is of the age of the Potsdam sandstone, 
the portion of the limestone next adjoining may be Calciferous. 
The mountain consists of fine-grained, gray gneiss, along with 
slate on the west, and at the southern end the gneiss contains 
minute zircons; I reserve the discussion of the age of the 
gneiss for another paper—the first draught of which was made 
nearly eight years since. 
(4.) But this Wappinger Valley limestone is not the only south- 
extension of the e limestone. Another (see Map) 
extends from it southward by the western foot of the Taconic 
Mountains through Boston Corners and Millerton; and in the 
vicinity of the latter place it has its limonite beds. Thence it 
takes a south-by-west course through Western Amenia, and 
