276 The American Geologist. April, 189-t 
investigations of the glacial drift, but long ago became entire- 
ly obsolete. * 
Another outcropping of nearly the same ancient opinions is 
found in the February number of the Nineteenth Century. 
Prince Kropotkin, who had written in the January number on 
the present lively interest and discussions concerning the the- 
ory of the formation of the drift by land ice, which lie ac- 
cepts and shows to be a full explanation for his own country 
( Russia), believing, too, that the Ice age was continuous, with- 
out definite interglacial epochs, is criticised in the ensuing 
number by the Duke of Argyll, who takes this occasion to 
place himself on the side of submergence and floating ice, or 
even the debacles of Sir Henry Howorth, rather than in alliance 
with his illustrious countrymen, Prof. .lames Geikie, the late 
Dr. James Croll, and Mr. T. F. Jamieson, who are in the first 
rank of glacialists. 
Doubtless one chief element in the current of present thought 
and studies on this subject, which especially gives countenance 
and encouragement to this extravagant early doctrine, now 
revived and again vigorously advocated, is the view recently 
advanced by the venerable and honored Prof. Joseph Prest- 
wich. who holds the place of Nestor among British geologists, 
accounting for the formation known as "rubble drift'' or 
"head," which has long been a puzzling problem in southern 
England, by the hypothesis of somewhat similar violent 
rushes of water, while the sea is supposed to have been flow- 
ing off from the land when it was being rapidly uplifted from 
a very brief submergence. This view is published in two 
most valuable articles, the earliest treating of the British rub- 
ble drift in pages 268-348, with a map and sections, in the 
Quarterly .Journal of the Geological Society, vol. xi.vin. for 
-Sit Pint'. J. Geikie's "Great Ice Age," chapter in. and LyelPs "Prin- 
ciples of Geology," eleventh ed., 1872, chapter \ i. In America the the- 
ory of the formation of the boulder-clay or (ill l>_\ icebergs or floes, 
during a period of submergence, appears to have been first proposed by 
Peter Dobson, of Vernon, Conn., from his observations of striated bould- 
ers found on tin' surface and at considerable depths in excavations (Am. 
.lour. Sci., first series, vol. x. Feb. 1826, pp. 'il?. 218). This was better 
than the theory of debacles or violent waves of water, as produced bj 
earthquakes, which were thought to carry the drift without the aid of 
floating ice. The chronologic order of the successive debacle, meteoric, 
denudation, iceberg, and land ice theories of origin of the drift, and 
their advocates, are fully set forth bv Prof. X. H. Winched in the Pop- 
ular Science Monthly, vol. in. pp. 286 289, July, is?:;. 
