Equivalence and Age of the Formations. 208 
York. In Vermont the Taconic slates (those of the central 
slate-belt) overlie the adjoining rear in one or more syn- 
clinals, as plainly shown in Mount Dorset, Danby ee 
Equinox Mountain, Spruce Peak. in Arlington, and Mou 
Anthony in Bennington ; ; and in Berkshire they have the same 
position, as observed in Graylock and Mount Washington. 
Hence in both States the Taconic slates overlie, or are younger 
than, the adjoining limestone. 
In Vermont, as Mr. Wing has shown, the limestone nearest 
the slate contains, in several places, Trenton fossils (Trinucleus, 
etc.), and at West Rutland, Chazy fossils (Maclurea, etc.) if n ot 
Trenton; and the slates are, therefore, as has been ‘already 
tated, younger than the Trenton limestone of that region and 
rise probably to the Hudson River or Cincinnati group. If 
this be true in Vermont, the Taconic range in Berkshire, since 
it is part of the same slate- belt, consists of rocks younger than 
the Trenton, and is therefore ee of the Upper Trenton or of 
the sro River or Cincinnati gro : 
may be questioned whether the Graylock Spur should be 
ptchides with the Taconic range, since it stands to the east of 
oat as first observed by Emmons. 
The Berkshire niinols of the band adjoining the Taconic 
range is mostly, if not wholly, non-magnesian, like that of 
Vermont. Hence its constitution, as well as its position, makes 
it altogether probable, that it is Trenton or Chazy, as in Ver- 
mont. The limestone west of the Taconic range in Hillsdale, 
Copake and farther south, must also be Trenton or Chazy since 
this is true for that similarly situated in Vermont; and, more- 
over, it is the west side of one and the same synclinal hexiie 
the Himéstone on the east side of the Taconic range passing 
beneath and coming up again on the west side. 
8. The Limestones and Schists of the Buen half of the limestone 
area.—Like the Taconic slates to the westward, these more 
eastern rocks in Berkshire are a continuation of those north of 
them in Vermont. The quartzyte is not all in one range. in 
either State; but, whether i in one or several mene it 168 alike 
