JACKSON GLACIER IS VISIBLE FROM GOING-TO-THE-SUN ROAD (BEATTY PHOTO)
Other important Park glaciers, although much smaller than the first two mentioned, are Harrison, Chaney, Sexton, Jackson, Blackfoot, Siyeh, and Ahern. Several others approach some of these in size, but because of isolated locations they are seldom seen. As a matter of fact, there are persons who visit Glacier National Park without seeing a single glacier, while others, although they actually see glaciers, leave the park without realizing they have seen them. This is because the highways afford only distant views of the glaciers, which from a distance appear much like mere accumulations of snow. A notable example is Grinnell as seen from the highway along the shore of Sherburne Lake and from the vicinity of the Many Glacier Entrance Station. The glacier, despite its length of almost a mile, appears merely as a conspicuous white patch high up on the Garden Wall at the head of the valley.
Several of the glaciers, however, are accessible by trail and are annually visited by many hundreds of people, either on foot or by horse. Most accessible of all Park glaciers is Grinnell. It can be reached by a six-mile trip over an excellent trail from Many Glacier Hotel or Swiftcurrent Camp. Sperry, likewise, can be reached by trail, although the distance is several miles greater than in the case of Grinnell. The trip, however, can be broken and possibly made more interesting by an overnight stop at Sperry Chalet, which is located about three miles from the glacier. Siyeh is the only other regularly visited Park glacier. It lies about half a mile beyond the end of the Cracker Lake trail, and can be reached from that point by an easy walk through grassy meadows and a short climb over a moraine. Siyeh, however, is less spectacular than either Grinnell or Sperry, being much smaller and lacking crevasses, so common on the other two. Few people make the spectacular trail trip over Siyeh Pass but those who do may visit Sexton Glacier by making a short detour of less than half a mile where the trail crosses the bench on which the glacier lies. Sexton is a small glacier, but late in the summer after its snow cover has melted off it exhibits many of the features seen on much larger bodies of ice.
Interesting surface features which can be seen at times on any of these glaciers include crevasses, moulins (glacier wells), debris cones, and glacier tables. Crevasses are cracks which occur in the ice of all glaciers. They are especially numerous on Sperry and Grinnell. Moulins, or glacier wells, are deep vertical holes which have been formed by a stream of water which originally plunged into a narrow crevasse. Continual flow of the stream enlarges that part of the crevasse, creating a well. Several such features on Sperry Glacier have penetrated to depths of more than 200 feet, and are 20 or more feet wide at the top.
No one can walk over the surface of Grinnell Glacier without noticing a number of conical mounds of fine rock debris. Actually these are cones of ice covered with a veneer, seldom more than two inches thick, of rock debris, so their name, debris cone is somewhat misleading.
CREVASSE IN SPERRY GLACIER
This rock material, usually deposited by a stream, protects the ice underneath from the sun’s rays. As the surface of the glacier, except that insulated by the debris, is lowered by melting, the mounds form and grow gradually higher until the debris slides from them, after which they are speedily reduced to the level of the rest of the surface. They are seldom higher than 3 or 4 feet.
A glacier table is a mound of ice capped, and therefore protected from melting, by a large boulder. Its history is similar to that of the debris cone. After a time the boulder slides off its perch, and then the mound of ice melts away.