in the vicinity of Great Barrington, Mass. 451 
H is the position of the Housatonic river, and a little south 
of the line of the section is the village of Housatonic. Near 
q?(pon the map) passes the road, first northeastward, then 
northward, to Stockbridge. As shown, there are in Monument 
Mountain two strata of quartzite, q', g%, with two of schist, 
(mica schist and gneiss) s', s*, all dipping southeasterly, the 
average slope 25°. 
_ The thickness of the upper quartzite of Monument Mountain 
1s 200 or 250 feet; that of the schist under it at least 500 feet; 
and that of the lower quartzite about 250 feet. 
The schist (s*) over the interior of Monument Mountain varies 
much in strike and dip, as is common in beds that are little 
inclined. The dip is for the most part to the east of south- 
east 20° to 25°, the strike being about N. 25° K. Just west 
of the eastern quartzite the amount of dip varied from 15° to 
25°, and the direction was generally that just stated: yet in 
Some places the strike was N. 50° W. an 70° W. At the 
There is no good outcrop of the lower schist (s') at the west 
end of Monument Mountain east of the Housatonic river; but 
the smooth surface of the foot hills or slopes in that part, 
and the sudden transition from numberless quartzite : 
ments to occasional masses of gneiss which is found on the 
descent of this side of the mountain, are evidence of its 
existence. Besides this, the stratum of schist is well exhib- 
i 
as 
farther west there is a bold ridge of quartzite, which is 
evidently the western side of the fold of the quartzite (¢’). 
A narrow depression or valley intervenes between the schist 
and this quartzite, so that the actual superposition of the 
former was not visible; but the dip of the schist was not only 
_ toward the quartzite on the east (as shown in the section), but 
also on the west of it in the Williamsville valley; and hence 
the quartzite is the course of a shallow synclinal. The 
quartzite was of the hard jointed kind, indistinct in its bedding. 
At one place I observed a westward dip of 20°—the strike 
N. 20° W.—in diyisional planes which appeared to be those 
of the bedding. 
