J. D. Dana—Hudson River Age of the Taconic Schists. 385 
character diminishes from these mountains westward toward the 
udson, just as it diminishes along their line northward toward 
Central Vermont. The rocks are mica schist and hydromica 
schist, and to the south micaceous gneiss, over the eastern part 
of Dutchess County; but, approaching Poughkeepsie, the schist 
in part fails even of the glossy luster, and becomes dull argil- 
laceous and partly carbonaceous schist. orth of Dutchess 
its extremity, south of Towner's, where, in a dry portion of a 
large marsh, north of Croton Lake, the limestone is ex 
view, alternating with coarse oneiss. In the slate ridge next 
est, the northern extremity of which is called Winchell’s 
Mou stad (west of Boston Corners and Millerton), the rock is 
argillyte, and hydromica schist, partly chloritic; but to the 
south, it becomes gradually coarser, being a mica schist on its 
eastern or more crystalline side, at Wassaic ; and ten miles farther 
south, a decided mica schist on its western side and still coarser 
on the east; and even gneissoid south of this.* Mather recog- 
nized the same changes, in this range of alata, stating it thus 
(Rep. N. Y. Geol., p. 433) : “in its northern part, of slate and 
talcose and chloritic slates; the middle part, of mica slate; and 
the southern portion, of gneiss.” The extremity of the “Great 
ntral” limestone belt is in the area of Croton lake.+ 
‘Taconian,” are here of one and the same age, a and they leave 
udson River Group. 
Quartzyte occurs adjoiaing the mea cea southwest of Mat- 
Satan, three miles from the Hudson River—a locality pointed 
out tome ie Mr. vege M. Woleott. of Pishkill The quartzyte 
* Acco section by Prof. N > Nalco (received by the author from 
him in eva) hes the top a yWinchell’s eg re n eastward to Lakeville, seven 
miles, along a ie is m. north of Millerton, the sk of Winchell’s Mountain west 
of the summit yte, and east of it mica schist; next east is the Millerton 
limestone aceite pei miles wide; next, mica schist, of the same width, having, 
on the West a thin stratum of “ beep. 29, brows hornblende schist, some cps mica- 
ceous” (as seen in a section on the Connecticut R. og egpe en, the 
Ramstons of Lakeville. tee ap is stated to obs north of east, cons age : Lakeville 
where there is a low anticlin 
_t It is rather peabable, that an anoles £33 exists two miles er south, in the 
Site of another pond south of Dykeman’s, though none is in a There is here 
a final termination of Se tlhe oe heh Archzean hills. 
