Excerpt from Memoirs of the Geological Survey of England and Wales: Explanation of Quarter Sheet 91 S. W. Of the One-Inch Geological Survey Map of England and Wales, Illustrating the Geology of the Country Around Blackpool, Poulton, and Fleetwood The district comprised within this quarter-sheet, may be physically divided into three areas. The central and largest consists of glacial drifts, rising to an elevation of 40 to. 130 feet above the sea, forming the western prolongation of the plain of Boulder Clay and sands upon which the towns of Preston and Kirkham are built, and which resting upon an ancient plane of marine denudation, composed of various rocks, stretches away from Grit hills of Chipping and Longridge, west ward towards and to the present sea-margin, at Blackpool and Bispham, where it abruptly terminates in a line of cliffs, from 50 to 75 feet in height. Both to the north and south this plain of Boulder Clay is bounded by a low escarpment sioping gradually down to a low-land plain, more or less covered with peat, which form the other two areas into which the district may be naturally divided. That to the north, is bisected by the River Wyre, which has spread its alluvium over the low-lying tract lying between it, and the coast at Rossall. That to the south though extremely small in the present sheet, is a portion of that great peat-covered lowland plain which has been described in the Memoirs and Explanations of 89 n.w., 90 n.e., and as sweeping round the entire coast of south-western Lancashire. It is worthy of note, that both in the lowland plain of the Fylde, and that of s.w. Lancashire, the peat (though often 20 and even 30 feet in thickness, and occurring at depths of 50 and 60 feet below the present sea-level) is generally underlaid by a marine, post-glacial deposit, which in quarter-sheets 90 s.e., and 89 n.w., consists of the Shirdley Hill Sand, and in the present quarter-sheet of the lpreesall Shingle proving that before the growth of the peat, and the obstruo tion of drainage during which the land was higher than at present, considerable denudation of the Boulder Clay plain took place, cliffs were formed, at the foot of which these marine sands and shingles were deposited. These cliffs, through the agency of sub-aerial agencies, have been gradually rounded so as to take the form now assumed by the lines of the Upper Boulder Clay escarpments, overlooking the peat covered tracts, one of which forms the boundary between the Boulder Clay, and the Peat, near the Blackpool Station of the Lytham and Southshore Railway. 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.