46 J. D. Dana— Geology of Vermont and Berkshire. 
Fig. 16 exhibits the stratification in Three-mile Ridge,—a 
ridge on the opposite side of Konkaput valley from Devany’s 
bluff, and shows the same succession essentially as on the 
Devany side—namely, limestone (that of the Konkaput valley) 
below ; next gee ti next a ere thickness of gneiss—not 
re than 800 feet. Three-mile Rid ge extends southwa 
5.S.E.), with rather an abrupt front, a shows in a distant 
view nearly horizontal lines of stratification. The dip is mostly 
25° to the northwest; but at base, toward the notch passed 
through by the road to Great Barrington, it is diminished to 
8°. The gneiss (as may be seen three or four hundred yards 
south of the notch) rests on a stratum of Berit yte. It is hard 
distinction between quartzyte and gneiss in Berkshire proves 
be of no more importance than that of quartzyte and hy 
mica slate in the quartzyte formation of Vermont. The soil 
conceals at this place the lower part of the quartzyte stratum, 
and the underlying rock or rocks; but, half a mile southeast- 
ward, along a road which runs nearly parallel with the moun- 
tain and not far from its base, and also between this road and 
the mountain, the limestone of the Konkaput valley outcrops 
with a small northwestward dip (15°-20°), conformable to the 
schist of the mountain ; ae these outcrops continue numerous 
for more than a mile. In o e knoll, toward the mountain, the 
beds were found to dip eueuesd, but this seg an exceptional 
ease. Elsewhere the dip was northwestwar d, and at one spot 
the limestone was seen directly overlaid conformably by the 
schist. 
I have above given the facts of my own observation. The same 
general conclusion with regard to the interstratification of these 
formations was long ago reached by Professor Edward Hitchcock, 
and announced in his Report on the Geology of Massachusetts. 
Bs Feat of the Leb pee ae he says (Report of 1841, p. 590) : “it 
ternates with and passes impercept ais His into gneiss and mica 
slate ; and in fact it Lok y very mperly be regarded as a mem- 
ber of the gneiss and mica slate form ” in Berkshire “it is 
frequently interstratified with gneiss Re, mica slate, especially 
along the eastern side of the valleys, as in Tyringham, Great 
on and Sheffield.” 
He also states (p. 573 and ea nd) that in Berkshire, the lime- 
stone occurs ae oe with the gneiss, mica slate, talcose 
slate and quartz rock of the region; that in New Malborough and 
SO Bg tee it is found in als between the strata of gneiss, as at 
adsell’s lime quarry ; and that its interstratification with woke 
