J. D. Dana— Hudson River Age of the Taconic Schists. 387 
wrench in the mass. On the southern portion of the east side 
both north and south of Kent, and also along a large part o 
the west side, the rock adjoining the limestone is quartzyte ; 
and next follows gneiss; the quartzyle in several places is gneis- 
probably the Potsdam sandstone; and in that case the con- 
formable gneiss will correspond to inferior beds of the Primor- 
dial, and the adjoining portion of the limestone belts may be 
Calciferous; further, the strata make an anticlinal over the 
intervening area of gneiss. This area includes some uncon- 
formable ledges, both in the northern and southern half, in 
which occur chondroditic limestone, syenyte, beds of titan- 
iferous magnetite, and hard gneisses, which may be Archean ; 
and if so, they are outliers of the large Archzean area of the 
Highlands which exists to the southwest. : 
3. INFLUENCE OF THE LIMESTONE BELTS ON THE FEATURES OF 
THE SURFACE. 
Limestone being a brittle rock, the region of flexures, whatever 
the thickness of the overlying mass, would have been profoundly 
fractured, especially in anticlinals; and being also a soft rock, it 
would have been easily carried away by denuding agencies. 
The limestone belts are the chief courses, as Percival pointed 
4, CONCLUSIONS. 
1. The Taconic schists are, according to the evidence, of the 
_ age of the Hudson River group. 
_ _ 2. The conformability in the rocks between the eastern of the 
_ Connecticut belts and the Hudson, being established by obser- 
_ Vation, the five limestone belts are sop! as above sugg 
__ but five outcropping bands of the Lower Silurian limestone for- 
mations, brought to the surface by a series of flexures. 
8. The.disturbance which upturned and crystallized the lime- 
_ Stones and other conformable Eanations in the Green Mountain 
_ area, through Vermont and Massachusetts, extended south over 
