METAMORPHIC ROCKS. 
441 
and are mostly quartz and granite ; but in the second class, the undoubted plutonic rocks 
abound, and consist of granite, sienite, greenstone, augite, serpentine, diallage, and intrusive 
metalliferous veins. 
I. METAMORPHIC ROCKS EAST OF THE HUDSON AND HIGHLANDS. 
These rocks range from Bennington and Shaftsbury in Vermont, in a direction about south 
through the -west part of Massachusetts and Connecticut, and the eastern part of New-York, 
in the counties of Dutchess, Putnam, Westchester and New-York, to Long^island sound and 
the Hudson river. 
Between the Taconic rocks as they have been described, and the Metamorphic rocks to the 
east of them, no well marked line of distinction can be drawn, as they blend into each other 
by insensible shades of difference. This is true as far as the Highlands, in and south of which, 
no trace of the Taconic rocks with such characters as have been described are visible in New- 
York.* 
The Metamorphic rocks intended to be described in the first class, do not fairly make their 
appearance in the State of New-York north of Dutchess county. There are a few localities 
in Lebanon, Canaan, Austerlitz, Hillsdale, Copake and Ancram, near the line of Massachu¬ 
setts, where the limestone might be referred to this class ; and some few localities have been 
mentioned where the limestone was white and highly crystalline, while describing the Taconic 
rocks. These rocks enter the State of New-York in the northeast corner of Dutchess county, 
from the south end of Mount Washington, and range thence in New-York to the city of New- 
York. 
The strata of these metamorphic rocks are very much broken, so that no stratum has been 
traced continuously for more than a few miles. 
The mica slate from Mount Washington crosses the valley of Oblong creek very obliquely; 
also the mountain which is called Chesnut ridge, south of Amenia, and Winchell’s mountain 
north of that place. The mica slate occupies about half the breadth of the mountain west of 
Amenia, on the turnpike from that place to Poughkeepsie ; and it forms most of the same 
mountain to the Highlands, as the western boundary of the Oblong and Dover valley. On 
the east of this range of mica slate (which blends off on the west into talcy and talcy argilla¬ 
ceous slate), the rocks are almost entirely of mica slate, crystalline white and grey dolomitic 
limestones, and quartz rock, eastward to the gneiss rocks near the Housatonic. In some 
places, garnets and crystals of staurotide are found in the mica slate, but they are not com¬ 
mon, and more frequently it shows a talco-argillaceous character, in New-York, indicative of 
its origin, except in the Highlands and farther south. • 
* It is necessary here to except the narrow strip of the Taconic rocks that passes through the Highlands, or just on the east 
■side of the mass of peculiar gneissoid and granitic rocks that forms the Highlands geologically, from near Shenandoah in Fishkil), 
to the mouth of Peekskill creek in Westchester county, and the extension of the same in Rockland county ; but in some parts of 
^his range, the rocks are so much altered, as would prevent their being recognized but for tracing them out. 
Geol. 1st Dist. 56 
