290 The American Geologist. May, 1895 
else evidence of any great reiidvance of the ice front, to the 
extent of lumdreds of miles which would be so required, at 
any time subsequent to the lowan stage. Only during the in- 
terval preceding that great renewal of ice accumulation have 
proofs of such extended oscillations of the ice border been as- 
certained, and these are areall}^ limited, if we except the lo- 
calities at and near Toronto, to the upper Mississippi basin 
from Ohio west to the Dakotas. From the Scioto river in 
central Ohio eastward 700 miles, to the Atlantic ocean south 
and east of New England, the moraines of the Wisconsin drift 
formation lie on or near the southern limit of glaciation. To- 
ronto lies far within this area which is almost wholly occupied 
by the late drift, and no other observations of allied intergla- 
cial deposits, like the plentiful and far spread notes of the 
forest beds farther west, are reported within the eastei'n area. 
Therefore it seems to me more probable that the ice-sheet was 
melted away from the region of the upper Laurentian lakes as 
far eastward as to Toronto, while 3'et it remained on the north- 
eastern part of the basin of lake Ontario, on northern New 
York, and the greater part of New England;* and that some 
species of the fauna so first coming into the region of Toronto 
were later compelled to retreat farther west when brought 
more fully into competition with the eastern fauna of the 
coastal region. The very rapid evolution now in progress 
producing the exceedingly' abundant species of insects is 
somewhat surprisingly shown by the changes, or less probably 
the extinction, of all the twenty nine species of beetles found 
in the Scarboro' delta deposits, whereas all of the numerous 
fresh-water mollusk species in the Toronto section are still 
living and unchanged. 
The evidence of two closely consecutive glacial recessions 
and reiidvances in Scarboro", and the thinning out of the 
thick deposits of till so formed within a few miles westward, 
imply that the ice border during that whole time was near, 
but seem quite inexplicable on the hypothesis that these till 
formations record great rejidvances of the ice, as either to the 
lowan stage or to the Wisconsin moraines. Furthermore, the 
*Am. Geologist, vol. xiv, pp. 63-G5, July, 1894. Am. Jour. 8ci., HI, 
vol. XLix, pp. 1-18, with map, Jan., 180.). 
