1887. | NEW YORK ACADEMY OF SCIENCES. a7 
the fact that Tom Ball is itself the course of a synclinal, sustains 
the above conclusion. Hence I now believe that there is in the 
region no second or upper limestone stratum.” 
Immediately after this, Prof. Dana describes the section at 
the south end of Beartown Mountain, four miles east of Great 
Barrington, in which the following succession occurs, com- 
mencing below : 
‘¢ 1, White granular limestone, that of the valley. 
. Mica-schist, a thin bed. 
. Hard jointed quartzyte, 30 feet. 
. Some limestone, 60 feet. 
. Quartzyte, like the lower, 20 feet. 
. Gheiss, 30 feet. 
. (North of the road) Bluish granular limestone, crum- 
bling. 
. Mica-schist, 6 to 8 feet. 
. Quartzyte, 100 feet (Devany’s quarry). 
“©10. Gneiss (overlying the quartzyte at the quarry).” 
Having had the opportunity to give special study in this region 
to the dolomyte tracts in the immediate vicinity of Great Bar- 
rington, on both sides of the river, I have worked out several 
facts in supplement or correction of the general section of Dana 
across the valfey at that point ; this I offer in modified form as 
Fig. 1. 
In the former section, the dolomyte of the little elevation of 
Mt. Peter, rising on the west part of the valley, was represented 
as lying in a stratum dipping steeply to the east. However, 
there are here many slight but significant variations in the dip, 
both in degree and direction, which seem to me to indicate the 
presence of one or more sharp folds, though with a general east- 
erly inclination. 
No rock was shown in the low ground between Mount Peter 
(P) and the Housatonic River (7); but I have found that the 
gneiss occupies at least part of this space near the river, in a 
highly tilted bed, dipping 60° to the west. 
Again, in the place of the hiatus between the river (H) and 
the east outcrop of the dolomyte on the right (Z), a coutinuous 
outcrop of the dolomyte occurs, down to the river and even in 
its very bed. Within the dolomyte tract itself, especially where 
freshly uncovered in quarries, many variations of the dip occur, 
which plainly indicate a series of five sharp and partly reversed 
folds, traversed by two faults. This conclusion has been reached 
from the following observations of the dip of the beds of dolo- 
myte, ona line passing eastward from the river to the base of 
East Mountain. 
Lay 
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