PRE-WISCONSIN DRIFT IN FINGER LAKE REGION 581 
this warping,’ it is not likely that the plane would define a surface even 
parallel to its original attitude. Concerning the relation which this 
part of our continent bore to sea-level while the Wisconsin ice-sheet 
was active, we have insufficient data to warrant any but very general 
conclusions. 
It is evident, then, that so far as the north-south valleys are con- 
cerned, exposures of the old drift are more apt to be found in a belt 
skirting the zone of heavy drift in the southern parts of the valleys; 
northward from this hypothetical belt erosion may have been very 
active, tending to remove the earlier deposits; southward, aggraded 
glacial rubbish has probably covered these deposits. 
Few of the quite mature transverse valleys belonging to an inter- 
rupted but well-developed drainage cycle, above alluded to, have been 
described.?- The more nearly transverse to ice-movement such valleys 
lie, the less ice-erosion they are subject to. Subsequent invasions 
of ice presumably have not removed much of the residual rock waste 
that escaped the earliest glaciation; nor would an earlier deposit of 
drift suffer great erosion. Consequently, valleys of this type are best 
fitted for the preservation of pre-Wisconsin drift. In the area covered 
especially by this paper two segments of such valleys, one extending 
eastward from the vicinity of Branchport (Penn Yan Quadrangle), 
the other extending westward from Dresden (Ovid and Penn Yan 
Quadrangles), have been studied. 
LOCATION AND DESCRIPTION OF THE PRE-WISCONSIN 
DRIFT IN QUESTION 
First indication of such drijt——In the area from Skaneateles to 
Keuka Lake the writer has often noted the highly weathered condition 
of smaller bowlders both on the surface and in cuts in the drift. Later 
acquaintance with the older drift in Ohio has led him to give further 
attention to this observation. These scattered, rather rotten crystal- 
lines may or may not suggest drift of different ages. 
1G. K. Gilbert, U. S. Geological Survey, Eighteenth Annual Report (1896-97), 
pp. 603-6; H. L. Fairchild, Bulletin of the Geological Society of America, Vol. X (1899), 
pp. 66-68. 
2R.S. Tarr, American Geologist, Vol. XXXIII (1904), pp. 271-91; F. Carney, 
Journal of Geography, Vol. II (1903), pp. 115-24. 
