J. D. Dana— Hudson River Age of the Taconic Schists. 377 
that the limestone along the eastern foot of the mountains 
(near or west of the nearest road to them) dips westward—the 
dip being found to be 45° to 60° to the west, with the strike 
between N. 3° E. and N. 8° W. (true). 
(2.) The recent discovery, by T. Nelson Dale, Jr., of fossils of 
the Hudson River group in the slates or argillaceous schists of 
Poughkeepsie, on the Hudson River, (sustaining the early 
views of the New York geologists, Professor W. W. Mather and 
Professor James Hall,) affords another line of approach to the 
Taconic Mountains of Massachusetts, and presents further evi- 
dence of their Hudson River age. In the first place, the lime- 
stone belt which lies, as above remarked, at the western foot of 
these mountains along through Hillsdale and Copake, and 
which is the western side of the mountain synclinal, branches 
off from Copake south-southwest through middle and western 
Ancram, and extends along the whole course of the valley of 
Wappinger Creek to'the Hudson River, which it reaches only 
four miles below Poughkeepsie, with a single interruption of 
less than three miles; and it is everywhere conformable to the 
argillaceous schists which border it on the east, including those 
of Poughkeepsie; and also with those on the west, except 
along a region of faulting near Bangall and Stissing Mountain 
(a range bordering the limestone area on the west between 
Stissingville and Pine Plains.) This continuation of the slates 
and limestone northeastward, from the Poughkeepsie region 
to the Copake, renders it highly probable that the same lime- 
‘stone formation which adjoins, and is con ormable to, the 
Hudson River slates or schists of Poughkeepsie, adjoins, is con- 
formable to, and underlies the schists of the Taconic Mountains. 
The limestone of Wappinger Valley is the Barnegat lime- 
stone of Mather—so named from a locality on the Hudson, 
river northeastward to Copake (not noting the break in it) ;* 
one mile of Newburgh, into the town of New Windsor, in 
Which it ends, not far from the Archean of the New Jersey 
Highlands, in a small body of water called Little Pond. ‘The 
Writer has examined the limestone at various points along the 
valley ; and he has found the conformability to the slates, stated 
by Mather, to be very generally true. The limestone area is 
’ d 437. In the h on p. 437 here 
daterred "Ma bias Ge aba we we die conrién Ul Go cane Duicbamn 
limestone areas, 
to, 
