592 
THE NATIONAL GEOGRAPHIC MAGAZINE 
At one's very feet, to the east, repose 
Hayden and Diller glaciers, their ghsten- 
ing white not out of harmony with the 
verdant forest fringe, which in this di- 
rection is of less importance than to the 
west. Farther out, the geometric out- 
lines of cultivated fields in the fertile 
valley of the Deschutes River are faintly 
discernible. 
At the north. North Sister, Collier 
Glacier, and a deployed series of lesser 
volcanic craters are for the moment quite 
overshadowed by the transcendent array 
of magnificence against the northern 
horizon. In all the splendor of their 
frigid though summer garb appear Mount 
Washington, Three Fingered Jack, the 
glacier-scored snow pyramid of splendid 
Mount Jefiferson, Mount Hood, lOO miles 
distant, and, in a favorably clear atmos- 
phere, Mount Adams, 50 miles beyond 
Hood, in the State of Washington. 
Fed by the snows which accumulate in 
a well-developed cirque at the northwest 
foot of Middle Sister, the Collier, in its 
mile and one-half of length, exhibits all 
the characteristics of a full-fledged Al- 
pine glacier. 
The Hayden and Diller glaciers at the 
east side likewise afford the student of 
glaciology most excellent opportunities 
to observe many features of glacial 
movement. Progress over their surfaces 
is easy or difficult, depending upon the 
slope of the different parts and the ex- 
tent to which the ice has been fractured 
and crevassed by irregularities in the bed 
over which it flows. 
As a rule the snow-fields at the head 
are comparatively level and passable. In 
the lower portions, where the deep s.i'^w 
has been largely compacted into solid icc, 
however, the variations in the rocky sur- 
face on which they lie often produce 
breaks that appear at the surface as par- 
tially covered ice-bound clefts or wide- 
open fissures, travel across which is 
either dangerous cr impossible. 
On steep inclines the climbing rope 
and ice-ax are essential to a reasonable 
degree of safety. Where the glacier 
proper starts down the steeper slope of 
the mountain, giant open cracks, called 
crevasses, are formed. 
As the ice-stream slowly settles down 
the slope, the crevasses continuously ,. 
formed above are in large part sealed 
again into firm ice. On the lower part 
of the glacier, however, where the bare 
ice is exposed free from snow, the sur- 
face is often deeply corrugated by what 
appear to be the accumulated remains of 
former open fissures. These are wide at 
times and their edges rounded by melting. 
Travel is difficult across such a surface, 
and possible only when footwear is prop- 
erly equipped with ice-calks to prevent 
dangerous slipping. 
The movement of a stream of glacial 
ice conforms in general to the laws of 
liquid flow. Contact with the sides and 
bottom of the channel retards movement, 
but ice, being- a brittle solid where not 
under heavy pressure, gives evidence of 
this drag by the appearance on the gla- 
cier surface, and especially near its bor- 
ders, of a network of joints or joint 
planes. 
The motion of the ice and its exposure 
to active melting so exaggerates the 
presence of these intersecting lines of 
weakness as to develop exceedingly 
roughened surfaces impossible of travel. 
The roughly angular blocks that are thus 
marked out in the ice-mass are termed 
"seracs," and to the resulting pinnacled 
surface the same name is applied. 
During the day the effect of insolation 
is seen in the many streams of water, in 
size from the trickling rill to the torrent, 
running on the t<~.p of the glacier. Few 
of these streams -proceed far before they 
drop into a cre-asse or other opening in 
the ice. The repeated daily work of such 
a stream often forms an "ice-well," a 
circular opening into which the water 
plunges to unknown depths, with a 
muffled ominous roar, to add its volume 
no doubt to the main stream that issues 
from the ice-cave beneath the snout of 
the glacier. 
The Three Sisters' region is not diffi- 
cultly accessible, and affords on the 
whole unexcelled opportunities for the 
study of varied phases of volcanic action 
and of the movements, character, and 
work of glaciers. With it all, the chance 
to exercise one's mountain-climbing pro- 
pensities is an item to be regarded as of 
first importance. 
