J. D. Dana—Taconice Rocks and Stratigraphy. 441 
is less coarse than that directly south in Salisbury, near Lime- 
rock Station. 
5. East of Sheffield village, and of the Housatonic River—The 
schist is the same arenaceous mica schist that occurs to the 
south in Canaan, and, as there, it alternates with, and often 
graduates into a great formation of quartzyte. North of Shef- 
field village, west of the Housatonic, the same quartzyte, partly 
micaceous, constitutes the south end of a ridge that extends 
north into Great Barrington. 
C. Conclusion. 
The facts here reviewed relate, it should be remembered, to 
a single stratum, that overlying the limestone. Since the 
ington and its absence from the schist of ridges farther east; 
(@) in the increasing size of the garnets and staurolites on go- 
ing eastward over Salisbury. 
(2) The change in mineral constitution, beyond what has been 
Stated in the preceding paragraph, is as follows: 
_@ Biotite mica, which is very sparingly present in the 
Winchell slates, increases in amount in eastern Salisbury, and 
1S much the most common kind in the arenaceous schists to the 
eastward. 
6. Granular quartz, which is very sparingly present in the 
Winchell slates, gradually increases in amount eastward, is 
Tather abundant in the southern part of eastern Mt. Washing- 
ton, and still more so in eastern Salisbury; and east of the 
Housatonic for a breadth of two miles or more it is the pre- 
ponderating constituent in the mica schist and composes quartz- 
yte strata. : 
c. Tourmaline in minute erystals is sparingly present in the 
Western schists and much less sparingly in the quartzyte and 
quartzytic mica schist to the eastward. : 
d. Garnets, which are not present in the Winchell slates, 
Am. Jour. Scr.—Tairp Series, Vou. XXIX, No. 174.—Junz, 1885, 
30 
