A Manual Of Elementary Geology

The Ancient Changes of the Earth and its Inhabitants as Illustrated by Geological Monuments

Excerpt from A Manual of Elementary Geology: Or the Ancient Changes of the Earth and Its Inhabitants He was soon informed by Mr. Logan, at that time engaged in the geological survey of Canada, that the white sandstone above Montreal was really much older than the Old Red, or Devonian. It had in fact been ascertained many years before, by the State surveyors of New York (who called it the Potsdam to lie at the base of the whole Silurian series. As such it had been pointed out to me in 1841, in the valley of the Mohawk, by Mr. James Hall, * and its position was correctly described by Mr. Emmons, on the borders of Lake Champlain, where I examined it in 1842. It has there the character of a shallow water deposit, ripple-marked throughout a considerable thickness, and full of a species of Lingula. The flat valves of this shell, of a dark color, are so numerous, and so arranged in horizontal layers, as to play the part of mica, causing the rock to divide into laminae, as in some micaceous sandstones. 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.

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