Upham.] 
228 
[April 17, 
glacial epoch. This was true of the “ Giant’s Kettles” near Chris- 
tiania, Norway, the largest of which, cleared from its drift under the 
direction of Professor Kjerulf, has a depth of about forty feet and 
diameter of eight to twelve feet ; also of the two much larger pot- 
holes near Archbald, Pa., described in the Annual Report of the 
Geological Survey of Pennsylvania for 1885. The Archbald pot- 
holes are one thousand feet apart and were both discovered in coal 
mining, their bottoms being in the coal bed. When the drift filling 
them was cleared out, one was found to be thirty-eight feet deep, 
with a diameter of about fifteen feet at the bottom, increasing to a 
maximum of forty-two feet and a minimum of twenty-four feet across 
its top ; and the second, the diameter of which is not definitely not- 
ed, was about fifty feet deep in rock, with a covering of fifteen feet 
of drift above. 
Further evidence relating to the time of formation of the “ Gi- 
ant’s Kettles” is supplied in Norway by their occurrence near the 
present sea level, where it is known, by fossiliferous marine beds 
overlying the glacial drift, that the land was submerged to a depth 
of several hundred feet beneath the sea when the ice-sheet was be- 
ing finally melted. During the departure of the ice, therefore, no 
water-fall through a moulin could wear these caldrons, because they 
were then below the sea level ; but, on the other hand, they were 
probably formed in this way when the ice-slieet was beginning to be 
accumulated. They may be accepted as proof that the land in pre- 
glacial or interglacial time had at least as great elevation as now, 
while the fiords indeed indicate that it was much higher. 
THE STRUCTURE OF DRUMLINS. 
BY WARREN UPHAM. 
The purpose of this paper is to record notes of several interest- 
ing sections of drumlins, and therefrom to gain whatever they may 
teach concerning the manner and time of the deposition of these 
remarkable hills of glacial drift. In this study, the literature of 
the subject has been collated, so far as it is known to me, including 
the following authors. One of these, Prof. William M. Davis, to 
