Prof. T. C. Chamberlin. 
45 
rupt terminal walls, which rise to heights of 50 to 150 feet.^ Not 
only are the ends of the glacial tongues vertical, but in most in- 
stances the sides are sc likewise. To some extent the edge of the 
ice-cap itself is vertical, though here a remarkable wind-drift 
border introduces a notable variation. The vertical walls face 
all points of the compass. It can scarcely be said that they do 
this indifferently, as only a few glaciers facing the north were 
visited; but these possessed a verticality altogether comparable 
to that of those which faced the east or west or south. There is 
little doubt that the cause of this is the low inclination of the 
sun’s rays, and the fact that these are directed against the ice 
from all points of the compass in turn. Rays of low slant strike 
the back of the glacier at a very acute angle, and hence glance 
away with great facility and little effect. On the edge of the 
glacier, however, they strike much more normally and effective- 
ly, while in low latitudes the opposite is true. In addition to 
this, the slanting rays of the sun striking the surrounding earth’s 
surface at low angles glance slightly upward and impinge upon 
the edge of the ice. In lower latitudes the rays strike the sur- 
rounding earth in a more nearly vertical direction and are thrown 
more directly back toward the sky. There are some instances 
in Inglefield Gulf where this verticality of margin does not ob- 
tain, but these are altogether subordinate in number and impor- 
tance to the mural habit. In the report of Lieutenant Greely these 
vertical faces are not inaptly likened to the Chinese Wall. 
The general phenomena observed in connection with the Disco 
glaciers and others of the southern type were in no way mark- 
edly different from the familiar phenomena of southern glaciers 
generally. There was little debris upon the surface. In the 
lower portion of the ice considerable rock material was embraced, 
and this to some extent appeared on the frontal slope at the ex- 
treme margin of the ice. It extended for a few rods back from 
the extreme edge, but did not in any notable way affect the upper 
surface of even the glacial tongues. No debris at all, except at- 
mospheric deposits, was seen upon the ice-caps proper, either 
4. It is scarcely necessary to say that I am here speaking of glaciers 
that end upon the land. Obviously those which reach the sea terminate 
in vertical walls through the breaking away of the ends. 
