Foraminifera from the glacigenic deposits at Broughton Bay, south Wales: a further test of the glacimarine model of deglaciation of the Irish Sea

Late Devensian shelly diamicton at Broughton Bay, Gower, South Wales has previously been interpreted as the product of either a glacimarine or terrestrial ice-sheet, both involving movement southwards into a shallow coastal embayment. Analysis of well preserved foraminifera from the diamicton is used to test critically which of these two models is more appropriate. The dominantly temperate character of the foraminifera indicates that the glacimarine model is inapplicable and that marine incursion of the embayment only occurred during temperate conditions. The results support a range of previously published sedimentological and molluscan faunal evidence showing a terrestrial ice-sheet origin for the diamicton, and conflict with amino-acid ratios on which the glacimarine interpretation at this site hinges. The paper confirms previous work showing that foraminifera can help to distinguish whether a terrestrial or glacimarine model of deglaciation of the Irish Sea Basin is more appropriate and that a good state of preservation of the fauna does not necessarily indicate a glacimarine origin.