PRE-WISCONSIN DRIFT IN FINGER LAKE REGION 583 
Northward along this slope a similar arrangement of drifts was 
noted in three places. 
On these steep slopes heavy rains and spring thaws open new chan- 
nels cutting 1o feet to 15 feet in a few seasons. ‘The Wisconsin drift 
is easily channeled; the other resists erosion more effectively. After 
a few seasons, however, the surface horizon weathers and covers the 
blue till formerly exposed. 
As explained above, the direction of this valley is more nearly 
accordant with the direction of ice-movement; the older drift here 
was exposed, therefore, to more vigorous erosion. ‘The portion of this 
old drift which has survived ice-erosion is the lower, unweathered 
parts. Thus the old drift is commonly fresher than the new. 
The North Crosby exposure.—On the opposite shore of the lake, a 
few rods up the hill from the North Crosby Landing, a recent stream 
course discloses a hard bluish till, which shows no evidence of struc- 
ture, overlain by Wisconsin drift. This channel in places is 15 feet 
deep; the maximum showing of the basal drift is about 45 feet where 
it forms the bed of the cut, but it is not constant, the Wisconsin some- 
times forming the entire cross-section of the cut. The hardness of 
the blue. till here is evident from the overhanging of the bowlders 
(Fig. 3), which may be two-thirds disclosed before dropping from 
the face of the cut. We have not seen in this material bowlders 
more than a foot in diameter. The sharp angle of slope which this 
till maintains in comparison with that of the Wisconsin above is 
evidence also of the compressive force to which it has been subject. 
Mixed ex posures.—About a mile southeast of Branchport, near the 
point where the old valley joins the Branchport arm of the lake, a 
creek trenches the recent drift, which here contains scattered masses 
of blue till. We noted one area at the foot of the channel wall which 
may be in place. The Wisconsin drift here alluded to appears to be 
from a lateral tongue of ice which fed into the valley, thus disturbing 
the older deposits. 
Another area where old drift is incorporated with the new is at the 
end of Bluff Point (Fig. 1). Here is a quantity of débris, largely local, 
dragged around the slope of the bluff. 
Keuka Lake Outlet exposure-—The most pronounced section of the 
- bluish till may be seen along the outlet of the lake. A typical expo- 
