4 
Frank Carney 
New York state; but this supposition is hardly in harmony with 
accepted facts concerning the centers of ice^dispersion. Theo- 
retical consideration, therefore, leads to the conclusion that in the 
Finger Lake region of New York the late Wisconsin drift sheet 
covers at least the ice-erosion remnants of older drift. Students 
of glacial geology have already tentatively presumed earlier glacia- 
tion in this region.® 
That there has not already been reported some observed evi- 
dence of pre-Wisconsin drift in the Finger Lake region is doubt- 
less due to one of two causes: workers may have felt that such 
drift should be highly weathered; or that at this distance north of 
the ice-margin erosion was so vigorous as to have removed the 
earlier drift. In all probability ice-erosion has removed most 
of the weathered horizon of the old drift, mingling it so thoroughly 
with fresh debris that it is not easily identified. In walking over 
the fields of the lake country one notes the presence of small bowl- 
ders which are very much weathered, bowlders that remind him 
of the general condition of stones in the areas of old drift; this is 
the most pertinent suggestion of the earlier glaciation of this 
region. 
PRE-WISCONSIN DRIFT IN GENERAL. 
The older drift sheets have been studied more thoroughly in the 
Mississippi basin than elsewhere; their chronological sequence is 
generally established on the degree of weathering exhibited. In 
the case of the Sub-Aftonian® and the Iowan, ^ the lithological con- 
tent is made a discriminating feature; the absence of water-laid 
material is a feature usually emphasized in describing the Kansan 
drift,® whereas the blue or blue-gray color of the unweathered 
Illinoian is pointed out.^ Where the formations of different sheets 
® R. S. Tarr, Journal of Geology, vol. xiv (1906), pp. 18, 19; Bulletin of the Geo- 
logical Society of America, vol. xvi (1905), p. 2lJ; H. L. Fairchild, ibid., p. 66. 
“ W. J. McGee, U. S. Geological Survey, Eleventh Annual Report (1891), 
P- 497* 
Chamberlin and Salisbury, Geology, vol. iii (1906), p. 384. 
® Ibid., p. 389. 
® F. Leverett, Monograph XXXVIII , U. S. Geological Survey (1899), p. 28; 
Monograph XLI (1902), p. 272. 
