26 
The American Geologist. 
January, 1896 
it be, as it seems to me, an expression of the physical con¬ 
ditions by virtue of which glaciers act as if they were viscous 
or plastic, ice after all has truly neither quality; nor is it 
fractured or bruised along innumerable infinitesimal planes 
throughout its mass, and again reunited by regelation. The 
heat of summer, and of unusually warm weeks or days, by 
quickening the interplay of the molecules forming the surface 
of the ice grains, so that one increases and another decreases 
more rapidly, is an important element to greatly augment the 
motion of the glacier; but in the coldest winter the reduction 
of the temperature is only a small fraction of the whole range 
downward to the absolute zero or absence of heat. The sug¬ 
gestive studies of Henry Moseley and James Croll, having 
special reference to temperature, are apparently superseded; 
but in their time they were needful contributions toward the 
attainment of this latest, and to my mind most intelligible, 
theory of physical processes which are clearly and unmistak¬ 
ably seen, but which have so long baffled the most learned 
and eager investigators. 
Lamination due to Differential Flow. 
After consideration of this Granulation Theory of the 
motion of glaciers and ice-sheets, I believe that the conspicu¬ 
ous stratification of the vast tabular icebergs discharged from 
the Antarctic ice-sheet, as observed by H. N. Moseley during 
the cruise of the Challenger,* the veined structure or lamina¬ 
tion reported by Russell in the still existing glaciers of the 
High Sierra ,\ the lamination, sigmoid folding, and faulting, 
seen by Hamberg in Loven’s glacier, Spitsbergen,| the very 
interesting similarly stratified, folded, and faulted ice layers, 
with much englacial drift, described by Chamberlin as form¬ 
ing the frontal cliffs of glaciers' and of the margin of the 
Greenland ice-sheet in the region of Inglefield gulf,§ and the 
tine lamination of the glacier ice seen by Deeley and Fletcher 
beneath the firn of Mont Blanc, all are due not to deposition 
of successive snowfalls, becoming so clearly defined in these 
*Notes by a Naturalist on H. M. S. Challenger, 1872-1876, chapter x. 
|U. S. Geol. Survey, Fifth Annual Rejjort, for 1883-81, pp. 318, 319. 
f Am. Geologist, vol. xvi, p. 200, Sept., 1895. 
^Bulletin of the Geol. Society of America, vol. vi, pp. 199-220, with 
eight plates, Feb., 1895: and a series of illustrated papers in the Jour¬ 
nal of Geology, vols. ii and .hi, for Oct.-Nov., 1894, and onward. 
