494 
Davis, j 
[May 18, 
beneath the ice to flow over the delta as the accumulation of sand 
and gravel increased. It is manifest that a clear and fresh sec- 
tion of the junction of an esker with a sand plateau would do 
much to settle this debated question ; and I have looked far and 
wide for so desirable an exposure ; but at present, it is not to 
be found. In its absence we are left largely to inference. 
The only objections that have been urged against the subglacial 
course of the streams that built feeding eskers and sand deltas in 
front of them is. first, that they must have flowed up-hill from 
beneath the ice to the delta level, and while thus flowing against 
gravity they must have carried up not only sand and gravel, but 
stones even a foot or more in diameter; and, second, that the 
surface of the esker is not covered with so many boulders as it is 
thought should be deposited there if the ice once lay above it. 
In answer to the second of these objections, I have supposed 
that the melting of the ice chiefly on the upper surface would 
release most of the drift that it contained, and that the greater 
part of the stones and gravel would be washed away to the mar- 
gin before and during the growth of the sand plateau ; for it is 
not necessary to suppose that the ice margin retained any great 
thickness at that time. The subsequent melting of the re- 
maining ice cover over the esker need not of necessity provide 
a sufficient supply of upper till to cover the surface of the esker. 
There is undeniably, however, some force in this argument. 
The up-hill transportation of the cobbles and gravel with the 
sand of the plateau along the subglacial esker channel to the level 
of the delta surface does not appear to me to present notable 
difficulties in its explanation. While the delta was growing at 
Auburndale, the back country was mostly covered with ice. The 
water flowing from the surface down the crevasses on the high- 
land area several miles north would afford a strong head to urge 
a plunging current under the ice mass still lying in the lowland ; 
and as such a current emerged at one place and another, it may 
easily have borne stones as well as sand along with it. 
16 . ANALOGY WITH ALASKAN GLACIAL STREAMS. 
Russell’s account of the streams issuing forth from the Malas- 
pina glacier in Alaska, bearing sand, gravel and stones, gushing 
upwards at the outlet like a fountain and building a stony flood- 
