The nature and maximum extent of glacial sediments off the west coast of Wales

Offshore drilling and coring together with high-resolution seismic surveys have established that the southern Irish Sea was extensively glaciated during the Devensian stage. Ice flowed southwards from Scotland and overran the western tip of the Lleyn peninsula, before competing with local Welsh ice in Cardigan Bay. It eventually terminated its advance at the southern entrance to St. Georges Channel. To date no glacial sediments have been found on the sea floor to the south of this limit.During deglaciation, the shallower regions of the Irish Sea area underwent a short but intensive period of erosion which produced numerous meltwater channels. These subsequently acted as traps for the deposition of estuarine sediments associated with the early stages of the Flandrian Sea Transgression. The reworking of glacial drifts by marine action occurred primarily during the passage of the Flandrian surf zone and in most areas has now ceased.