Pre-Glacial Topography 1

Abstract

THE beautifully illustrated memoir by Messrs. Wright o and Muff, recently issued by the Royal Dublin Society, directs attention to an ancient rock-platform on which Glacial deposits were laid down in southern Ireland. The importance of such observations is clear when we consider the possibility of the preservation of a pre-Glacial, and perhaps Pliocene, fauna in favoured localities beneath the drift. At Courtmacsherry Bay, for example, south-West of Cork Harbour, a well marked rock-shelf occurs about 5 feet above high-water mark. On this rests a raised beach, with ferruginous sand and rows of pebbles, succeeded by the blown sand that accumulated when the uplift first occurred. Blocks from the adjacent cliff slipped down over the sand, and the series was then preserved by the Boulder-clay of the Glacial epoch. The wide stretch of coast, from Carnsore Point in co. Wexford to Baltimore in the west of co. Cork, over which this raised platform has been traced, affords ample opportunities for comparing the modern with the ancient features. The authors show that the pre-Glacial sea worked against a cliff about 100 feet in height, and consequently advanced slowly, leaving a denuded surface remarkably free from stacks and irregularities. This surface commonly lies about 12 feet above the modern beach. Unfortunately, no trace of fossils has yet aooeared in the old beach-deposits, and the authors believe that even pebbles of limestone have been removed by percolating1 water. The Boulder-clay above contains the usual molluscs, including northern species.