THE SLATES OF THE TACONIC MOUNTAINS, ETC. 709 
summit, called Mt. Everett, 2,634 feet in height above the sea, 
the limestone of the Sheffield plain was found to have, in- 
stead of the usual easterly dip, a westerly dip, and -this cbmuined 
up the slopes of the mountain as far as the limestone extended, 
about 120 feet above the plain and there the limestone was seen to 
pass directly beneath the slates of the mountain, these having the 
same dip and strike, the dip 20° to 25.° Thus the limestone was 
seen to descend under Mt. Washington and the slates to be the 
superior rock. Following along the base of the mountain north- 
ward, this dip of the Stockbridge limestone under the mountain 
was found to continue for nearly four miles, that is along the 
whole eastern front. 
These facts seem to prove that the limestone of Berkshire goes 
under Mt. Washington and comes up in the great limestone of 
Copake on the west side of the Taconic range. 
I might show that there are probably two close-pressed syn- 
clinals in the Mt. Washington plateau (which is four to five 
miles broad), with steep easterly inclined axes, and that these 
synclinals are synclinals of slate riding over a single broken syncli- 
nal of limestone; that, to the north of the mountain, where the 
mountain descends to the limestone plains of Egremont, these syn- 
clinals become separated and include an anticlinal of limestone, 
the limestone of the anticlinal appearing in the intermediate 
valley while the ridges (synclinals) are slate; and that the two 
synclinals have an eastwardly inclined axis, the dip being very 
steep to the eastward. But to explain fully would require 
diagrams, and I leave the details for another place. 
Graylock in northwestern Massachusetts, to the east of the line 
of the Taconic, and 3500 feet in height, whose rocks are much like 
those of Mt. Washington, is described by Emmons as a synclinal ; 
and, after a survey of the facts on the ground, observing the 
westerly dip of the limestones of the eastern slopes near South 
Adams, and the easterly dip on the western slopes near the en- 
trance to the “Hopper,” as the great central valley is called, I am 
satisfied that he was right. The dip at the summit and most other 
parts is very steep to the eastward. It appears then to be a result, 
like many other Berkshire Mountains, of a squeeze of the slates 
in a synclinal; and like Mt. Washington it is probably not a sim- 
ple synclinal. It may be ‘a double one, with the Hopper corre- 
sponding to the intermediate anticlinal, the beds of the whole 
