MOHAWK LAKE BEDS. 
393 
Some of the moraine material poorly exposed on the op¬ 
posite (west) side of Jamison Creek at the same elevation 
(about 5,000 feet) shows less evidence of stratification. 
In the bed of Jamison Creek just below the bridge at 
Jamison, a shaft was sunk some years ago to the depth of 
270 feet, all in gravel. This shaft is still to be seen. There 
must therefore be an enormous amount of detrital material 
here. 
The town of Johnsville rests on a terrace-like embank¬ 
ment, the upper part of which shows some stratification. A 
similar though narrower terrace exists on the east side of 
Jamison Creek opposite Johnsville. The stratified material 
could not have been deposited when the canon was filled 
with ice and may have been formed by a slight damming 
up of the waters of the creek after the retreat of the glacier. 
On the west side of Mohawk Valley, at an elevation of 
about 5,000 feet, is Bennett’s hydraulic mine. The upper 
part of the material washed is clay with scratched boulders, 
traces of a rough stratification being visible, which may have 
been due to water from melting ice. 
A little lower down, however, the material is more arena¬ 
ceous, shows bedding plainly, and is traversed by normal 
faults at two points, the down-throw of each being toward 
the valley at an angle of perhaps 30° from vertically, and 
the throw in each case being about one foot. This lower 
material is thought to represent the highest terrace of Mo¬ 
hawk Lake. The inclination of the stratification is toward 
the valley or easterly, and this may be explained by the 
steepness of the slope on which it was deposited rather than 
by any subsequent disturbance. The well-worn gravel at 
Bennett’s hydraulic mine is thought to have come from an 
old river channel that formerly existed higher up on the 
slope, remnants of which are still to be seen. 
There are frequent large boulders of diabase on the lake 
beds near the north end of the area, where the outlet of the 
lake presumably was, and these may have been brought to 
their present position by floating ice. There is no diabase 
50—Bull. Phil. Soc M Wash., Vol. 11. 
