Page:Popular Science Monthly Volume 46.djvu/24

14 areas of continuous drift. How vast, manifestly, have been the changes which marked the landscape during and since the period of greatest ice! The period of recession seemingly still continues, but how far the results of this recession will extend can not be told.

The insignificant development of the ice cap, in its relation to the large glacial streams which radiate off from it, is so striking a peculiarity in some parts of Greenland as to have suggested the suspicion that many of the existing glaciers are merely relics of the great Ice age. Bessels, the accomplished scientist of the Polaris Expedition, indeed, gives voice to this feeling in explanation of the by no means insignificant glaciers of Herbert and Northumberland Islands, lying somewhat north of the seventy-seventh parallel of latitude, which descend from an ice cap of eighteen hundred to two thousand five hundred feet elevation. It did not appear to him probable, or even possible, that the comparatively feeble accumulation of snow which is found at this elevation could originate ice streams of the dimensions which are there found. The facts, however, show that there is no real basis for this interpretation. The snow covering of these islands belongs to themselves, and, feeble though it be, it is quite competent to explain the associated phenomena. Many of the "hanging glaciers" of Herbert Island, which descend over slopes of some thirty to thirty-five degrees, are so attenuated in their upper parts as to be almost extinguished before reaching the summer ice cap; yet basally they rapidly increase in dimensions, so that before they finally terminate they measure not less than forty to fifty feet in thickness. The slowly accumulating snows descend over the first-formed layers, whether by sliding or otherwise, and help to build up the base while they thin out the top. In all essential respects these hanging glaciers are identical in structure with the larger streams, and it is only in their narrow connection with the ice cap that they at all differ. I am indeed convinced that some of the minor glaciers have been formed without the assistance of any ice cap or of the accumulated snows of a névé basin; for such streams, which are seemingly not very numerous, the designation of ravine or couloir glaciers might, perhaps, be advantageously used.

Briefly recapitulated, the glacial phenomena of Greenland are the phenomena of all other glacial regions; they are not illustrative of new forces and involve no explanations that have not already been made familiar through the teachings of other countries.