Davis.] 
490 
[May 18, 
that that is sufficient reason for believing that all eskers are of 
the same origin. 
As the esker is followed toward the sand plateau with which it 
becomes confluent, it commonly becomes broader and more irreg- 
ular in form ; and at the same time, its sides are somewhat pitted 
with smail hollows ; it sometimes gives out branches, excellently 
shown in the feeding esker of the Newtonville sand plateau, two 
miles east of Auburndale ; and at the same time, the adjacent low- 
land surface becomes more or less encumbered with sand mounds 
or kames. I interpret all these changes to mean that, in walking 
along the esker from its head to its junction with the sand pla- 
teau, we are advancing from the more solid and continuous mass 
of the ice towards its decayed margin, where it is dissected by 
numerous channels ; and that while the main stream flowing from 
the ice followed the course now marked by the chief esker, the 
side streams are indicated by its branches, and various sluggish 
currents are implied by the sand heaps or kames which filled the 
irregular spaces among the melted ice. All this is so generally 
recognized that we may turn at once to the more special question 
on which general agreement is not yet reached. Is the esker the 
deposit of a superglacial or of a subglacial stream ? 
The general absence of disturbance in the sands and gravels at 
the head of a sand plateau indicates that the ice-sheet, when the 
delta grew at its margin, was essentially stagnant. The curva- 
ture of the esker ridge and the inequality of jits crest line are 
inconsistent ivith a forward movement of the ice over it. The 
kames tell the same story, for at the front of an active glacier 
we should not expect to find the ice margin consisting of sepa- 
rated ice masses. The kettles in the sand plain confirm the con- 
clusion ; for they indicate ice blocks, whose presence held their 
space free from the sand which grew up around them, and whose 
subsequent melting left the kettles empty. If any motion was 
retained in the ice -sheet near the margin, it must have been very 
slow and sufficient only for the slight pushing of the beds seen at 
the cut by Lee’s Hotel. 
11 . RAPID DEPOSITION OF ESKERS AND SAND PLATEAUS. 
When one first views the extended surface of a large sand 
plateau or delta, it is assumed that a considerable lapse of time, 
