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OverviewExcerpt from Lake Agassiz: A Chapter in Glacial Geology The superficial material which'overlies the bed-rock with 111 this northern glaciated area has everywhere beeh ploughed up and worked over by the slowly moving ice-sheet, and at its disappearance was left in a deposit of, clay, sand, gravel and boulders, mixed in one confused mass, which 18 called till. Except in the valleys, as 'of the Mississippi at Minneapolis, where streams have assorted the'se materials and spread them in layers, the till forms the surface of nearly all of Minne sota, its thickness being from 50 to 250 feet. It is the Stony and gravelly clay, in which cellars and wells are dug; and it forms a sheet of such great extent and. Thickness that about half of the counties of western Minnesota contain no exposures of the underlying older rocks. 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. Full Product DetailsAuthor: Warren UphamPublisher: Forgotten Books Imprint: Forgotten Books Dimensions: Width: 15.20cm , Height: 0.20cm , Length: 22.90cm Weight: 0.059kg ISBN: 9781334497452ISBN 10: 1334497451 Pages: 34 Publication Date: 27 July 2018 Audience: General/trade , General Format: Paperback Publisher's Status: Unknown Availability: In stock Limited stock is available. It will be ordered for you and shipped pending supplier's limited stock. Table of ContentsReviewsAuthor InformationTab Content 6Author Website:Countries AvailableAll regions |