296 The American Geologist. November, i898 
are the predominant or the only form of water erosion in their 
vicinity; but at the falls of ordinary streams, pot-holes are ex- 
ceptional, or a subordinate feature, among more extensive 
grooving and other fantastically waterworn sculpture. It 
is evident, too, that glacial planation, ensuing after the moulin 
origin of the giants' kettles, although probably in many places 
effective to intensify this contrast, cannot generally be its chief 
explanation, which is rather to be found in the protection af- 
forded by the ice covering the rock contiguous to the base 
of the moulin. The rebounding water, indeed, welling up 
from one side of the rock kettle, may perhaps have usually 
flowed away, for its immediate exit, in an englacial tunnel, or 
at least with some drift between it and the rock. The condi- 
tions of erosion of the giants' kettles prevented or minimized 
contiguous waterwearing, which, on the other hand, is favored 
and predominant wherever pot-holes are made l)y subaerial 
streams. 
In Vermont and New Hampshire pot-holes have been ob- 
served by Profs. Edward and Charles H. Hitchcock, and by 
the present writer, in localities where they must be referred 
to the Glacial period. Sometimes, on hills and mountains and 
on lake shores, they were undoubtedly due to moulins ; but in 
several instances they occur at cols over which the outlets 
of ice-dammed lakes appear to have passed.* On the sea- 
shore in Cohasset, Massachusetts, subglacial pot-holes have 
been described and figured by Mr. T. T. Bouve;t and nu- 
merous others of similar origin are known in that state, but 
await publication. Indeed, they are of frequent occurrence, 
but mostly remain undescribed, throughout the entire glaci- 
ated region of the United States and Canada. 
The most remarkable known of these giants' kettles, wheth- 
er we consider their size or the manner of their occurrence 
and discovery, are two found in 1884 and 1885 in Lackawanna 
county, Pennsylvania, about three miles northwest of Arch- 
bald. As described by Mr. C. A. Ashburner, the x\rchbald 
pot-holes are 1,000 feet apart and were both discovered in 
*Geology of Vermont, 1861, pp. 216, 930; Geol. of N. H., vol. Ill, 
1878, pp. 64-66, 249. 
f'lndian Pot Holes, or Giants' Kettles of Foreign Writers," Proc. 
Boston Soc. Nat. Hist., XXIV, 1889, pp. 219-226; with discussion by 
Warren Upham, pp. 226-228. 
