Man and the Glacial Period

by G. Frederick Wright

In other places I have witnessed the formation of a long ridge of gravel by the gradual falling in of the roof of a tunnel which had been occupied by a subglacial stream, and over which there was deposited a great amount of morainic material. As the roof gave way, this was constantly falling to the bottom, where, being exempt from further erosive agencies, it must remain as a gravel ridge or kame.

In other places, still, there were vast masses of ice covering many acres, and buried beneath a great depth of morainic material which had been swept down upon it while joined to the main glacier. In the retreat of the ice, however, these masses had become isolated, and the sand, gravel, and boulders were sliding down the wasting sides and forming long ridges of débris along the bottom, which, upon the final melting of the ice, will be left as a complicated network of ridges and knolls of gravel, enclosing an equally complicated nest of kettle-holes.

Beyond Cross Sound the Pacific coast is bounded for several hundred miles by the magnificent semicircle of mountains known as the St. Elias Alps, with Mount Crillon at the south, having an elevation of nearly sixteen thousand feet, and St. Elias in the centre, rising to a greater height. Everywhere along this coast, as far as the Alaskan Peninsula, vast glaciers come down from the mountain-sides, and in many cases their precipitous fronts form the shore-line for many miles at a time. Icy Bay, just to the south of Mount St, Elias, is fitly named, on account of the extent of the glaciers emptying into it and the number of icebergs cumbering its waters.

In the summer of 1890 a party, under the lead of Mr. I. C. Russell, of the United States Geological Survey, made an unsuccessful attempt to scale the heights of Mount St. Elias; but the information brought back by them concerning the glaciers of the region amply repaid them for their toil and expense, and consoled them for the failure of their immediate object.

Fig. 14.—By the courtesy of the National Geographical Society.

Leaving Yakutat Bay, and following the route indicated upon the accompanying map, they travelled on glacial ice almost the entire distance to the foot of Mount St. Elias. The numerous glaciers coming down from the summit of the mountain-ridge become confluent nearer the shore, and spread out over an area of about a thousand square miles. This is fitly named the Malaspina Glacier, after the Spanish explorer who discovered it in 1792.

It is not necessary to add further particulars concerning the results of this expedition, since they are so similar to those already detailed in connection with the Muir Glacier. A feature, however, of special interest, pertains to the glacial lakes which are held in place by the glacial ice at an elevation of thousands of feet above the sea. One of considerable size is indicated upon the map just south of what was called Blossom Island, which, however, is not an island, but simply a nunatak, the ice here surrounding a considerable area of fertile land, which is covered with dense forests and beautified by a brilliant assemblage of flowering plants. In other places considerable vegetation was found upon the surface of moraines, which were probably still in motion with the underlying ice.

Greenland.—The continental proportions of Greenland, and the extent to which its area is covered by glacial ice, make it by far the most important accessible field for glacial observations. The total area of Greenland can not be less than five hundred thousand square miles—equal in extent to the portion of the United States east of the Mississippi and north of the Ohio. It is now pretty evident that the whole of this area, except a narrow border about the southern end, is covered by one continuous sheet of moving ice, pressing outward on every side towards the open water of the surrounding seas.