l8o The American Geologist. Septembur, isiw 
criminate here and restrict the word kame to the typical sub- 
aqueous deposits and find another term for the subaerial ac- 
cumulations. 
Kettles. — Perhaps less progress has been made in explana- 
tion of the hollows or bowls called "Kettles" than of any other 
glacial phenomenon. The explanation of their origin made 
by Edward Hitchcock in 1841, that they were produced by the 
melting of buried masses of ice, is still the common interpreta- 
tion of their genesis. In 1859 this idea was adopted by Whit- 
tlesey in his paper on the "Drift Cavities or Potash Kettles of 
Wisconsin." In 1877 professor Chamberlin mentioned four 
possible causes of Kettles: (i) irregularities of heaping; (2) the 
pushing of one drift ridge unconformably against a preceding 
one; (3) the incorporation of ice blocks; and (4) under-drain- 
age. In 1884 Dana thought the basins in the gravel terraces 
of the New Haven region were produced by eddies in the 
flowing water; but these have been examined by J. B. Wood- 
worth who pronounces them typical ice-block kettles. Those 
irregular depressions, sometimes of large size, which occur in 
water-laid drift, suggesting the name "pitted plains," have re- 
ceived no other acceptable explanation than that of ice-block 
genesis, although still regarded by many geologists as of un- 
certain origin. 
It seems probable that "kettles" may be of various origin. 
Some of those in moraine and kame deposits may be due to 
irregular piling of the drift, while others were most certainly 
occupied bv ice blocks during the deposition of the drift. 
Some of those in delta terraces are evidently due to deficient 
filling by the capricious action of shore and stream currents. 
The larger and deeper ones in river terraces or in deltas, giv- 
ing rise to the name "pitted plains" are most probably of ice 
block origin. 
The literature of the subject is scanty. Among later writ- 
ers are Mr. Upham and professor Woodworth. The latter 
has endeavored to estimate the size of the ice blocks from a 
study of the kettles. 
Valley Drift, Terraces. — The enormous quantity of water- 
laid drift in the stream valleys leading south from the glaciated 
areas, as well as within those areas, was the firmest basis for 
the diluvial hypothesis of the drift; and the early literature 
