Abstract
The results of detailed sedimentological work on Pleistocene deposits at Broughton Bay, west Gower, are presented. Ipswichian raised beach sediments are overlain by a sequence of Devensian glacial and periglacial deposits and by Holocene dune sand. Particle size, clast fabric, lithological and SEM microtextural evidence show that three types of Pleistocene glacigenic deposit are present: (1) a lower, ‘bedded’ till series characterized by fine-grained, shelly diamictons; (2) an upper, stony till; and (3) till re-deposited by solifluction. Facies variations within in situ till were caused by the vertical transfer of materials within the basal ice layers, as marine and estuarine sediments were entrained from the floor of Carmarthen Bay by southward-moving ice. These basal sediments, together with more far-travelled, englacially-transported material, were deposited contemporaneously on west Gower, at or near the maximum limit of the Late Devensian Welsh ice sheet. The sedimentological and dating evidence is best explained by a conventional model of ‘terrestrial’ Late Devensian ice moving southwards onto Gower with a regionally stable landmass and eustatically-lowered sea-level. Reasons for rejecting a glaciomarine origin for the sediments are discussed. Soliflucted till, colluvial sediments and frost cracks at the site reflect periglacial activity towards the end of the Devensian Stage.
Published Version
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