4 The American Geologist. •^"^^'' ^''''-- 
charged bv the slow process of ablation from the frontal slope 
of the ice, the conditions thus favoring the aggrading or build- 
ing up of the beds of the subglacial streams by still coarser detri- 
tus which the deepening water cannot urge to the outlet. In 
short, we appear to find here all the machinery usually regarded 
as essential to the subglacial origin of eskers. 
But eskers are not a conspicuous feature of the land between 
the Malaspina glacier and the shore, across which the margin 
of the ice has recently receded — a tract which, though divided by 
the Sitkagi blufifs, aggregates nearly seventy miles in length. 
It is natural that it should be so, since, granting, for the sake 
of the argument, that ridge-like deposits of gravel may be 
formed in the earth-bottomed ice tunnels occupied by these 
impetuous subglacial streams, they must also inevitably be ob- 
literated or buried by the agency of the same streams, as fast 
as thev are exposed by the recession of the retaining w^alls of 
ice and brought within the zone of extremely rapid fluvial 
deposition, where the overloaded streams are building their 
detrital cones. In fact, although scores of subglacial streams, 
are escaping from the southern margin of the Malaspina gla- 
cier, Russell has noted on this marginal plain, several hundred 
square miles in area, but one esker, or distinct ridge of gravel,, 
which is clearly the product of deposition and not of erosion. 
This is on the north side of and parallel with Kame stream ; 
and is described as a sharp ridge of well-rounded gravel which 
is seen in places to rest on an icy bed and was evidently depos- 
ited by a 'Stream which flowed fully one hundred feet higher.* 
Again, it is said to date from a former stage when the waters 
flowed about one hundred feet higher than now and deposited 
a long ridge of gravel on the ice.f Having been formed on the 
ice, it is probably to be regarded as the product of a supergla- 
cial or englacial stream, and not of a subglacial stream, such as 
Kame stream is today. 
It appears probable that the principal subglacial streams of 
the Alalaspina glacier are but little constrained by the ice, or 
at least that their courses are conformable to the ground topog- 
raphy to the extent that they nowhere flow uphill ; and quite 
certainly we may assume that they do not show the utter dis- 
* Am. Jour. Sci. 143, p. 180. 
':Jour. Geol. 1, p. 240. 
