Page:Popular Science Monthly Volume 40.djvu/360

346 and representations of bowlders possess but little interest other than what pertains to peculiarities of size, shape, and location; while the agencies mainly concerned in the formation, movement, and distribution of the bowlder, as well as of the ordinary pebble, which is a miniature bowlder, have long ceased to be matters of controversy. With those not versed, however, in geological evidence and reasoning, the case is far different. To most of such, the attributing of the phenomena under consideration to the motor power of ice seems so fanciful and unnatural that the agency of the Indian (as has come within the experience of the writer) has appeared more reasonable. But if any one thus doubting will but acquaint himself with the present condition of Greenland, where we have a continental area covered with a sheet of ice of immense thickness—a mile or more, doubtless, in many places—continually accumulating through almost constant atmospheric precipitations, and moving, through the weight and pressure of such increments of snow and ice, with almost irresistible force from the center of such continent to its sea or coast line, and then in imagination transfer and reproduce such conditions (which are undoubted actualities) over the whole of the northern United States and Canada, he will be abundantly satisfied that the most striking of bowlder phenomena constitute but a very small measure of the forces that were concerned in their production and were concurrently exerted to modify the earth's surface—even to the extent of removing mountains.

It will also widen the sphere of interest in this subject to refer to the humbler but at the same time most instructive memorials of the Glacial period, which are, as it were, associated with the bowlders, and help to conceal the barrenness and desolation of the "drift"; namely, the pretty flowering plants like the "dandelion" and the "trailing arbutus," and others, which are believed to have come down in the Glacial period from their natural habitat in the far north to our present temperate zone, and to have remained, after the disappearance of the ice, with the bowlders as if to keep them company. Recent explorers of Greenland tell us that wherever in little sheltered nooks upon its dreary coast the ice and frost relax sufficiently in the brief summer to admit of any vegetation, these plants grow and flower most luxuriantly, while in their foreign homes they seem, as every one knows, to choose those times and temperatures for blooming and fruition—i. e., in the early spring—which are most in accordance with the conditions of their origin and primal existence; thus apparently reasserting their feræ naturæ, as did the old vikings when associated with the more delicate types of southern latitudes.