Author:

Publisher: Forgotten Books

Published: 2017-06-30

Total Pages: 538

ISBN-13: 9780282745196

Excerpt from Appalachia, Vol. 11: The Journal of the Appalachian Mountain Club, 1905-1908 Around the reservoirs of many glaciers we find steep clifis from which rocks are continually falling. They are covered up by the snow, follow their course along the lines of flow through the body of the ice, and are brought to the surface near the end of the glacier. It is an interesting observation that glaciers whose reservoirs are surrounded by rapidly weathering clifis have their lower ends thickly covered with moraine material; whereas glaciers originating on high plateaus have perfectly clean ends, a peculiar difference entirely explained by the dis position of the lines of flow. There is no necessity, therefore, to ascribe this material to ground moraines. The accumulation of snow in the reservoir increases from the neve line for some distance _up, and as the annual deposits accumulate they flow downward and forward; each tributary or, indeed, each recess in the surrounding mountains forms its own layers of strata, and as these flow into the general trough, they are compressed and folded so that their outcrops on the surface of the ice are usually long loops pointing down stream. It frequently occurs that this folding does not show itself near the neve line, but appears further down the dissipator, at the lower ends of the lines of flow, whose origin lies far up in the reservoir where the folding begins; so that we find reproduced in the dissipator certain characteristics of the upper reservoir. Glaciers which have no well differentiated tributaries may, nevertheless, have their dissipators divided longitudinally into different systems of loops, which represent the outcrops of the folded strata from the recesses above; and the lines separating these parts, hardly distinguishable in the upper part of the dis sipator, become stronger and stronger as they approach the end of the glacier. If this dividing line really separates two tribu taries which have united in the reservoir, it will probably develop into an internal moraine. This is beautifully illustrated in the great Aletsch glacier (plate IL). After the sun has set, the whole surface of this glacier, when seen from the summit of the Aggischhorn, shows most beautiful systems of loops resem bling the line of a fine engraving. These systems are separated by longitudinal lines, faint at first, but growing more and more marked, and one of them becomes the great median moraine, so prominently seen at the end of the glacier. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.