The Geological Magazine, Vol. 9

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Excerpt from The Geological Magazine, Vol. 9: January-December, 1872But when we come to seek an explanation of the shape of the cirque, the case is not so clear. If they were always in places where many streams from above converge, this might, as Mr. Bonney suggests, cause a more rapid destruction of the rock at that locality, chie¿y, however, I should suspect, by atmospheric action on the wet surface. A quaquaversal dip would also be favourable to the production of a cirque, the reason being, because the maximum resistance to destruction is not attained until the exposed face is perpendicular to the plane in which the dip lies, or, in other words, is parallel to the strike. The exposed lines of bedding would in that case appear horizontal.In a homogeneous rock a hollow once formed would become enlarged by disintegration in all directions equally, so that a vertical chasm would in time become a cirque. Such may be the principle on which cirques in Syenitic rocks may have been formed.About the PublisherForgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.comThis 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.