Late pleistocene (Devensian) glaciofluvial outwash at Banc‐y‐Warren, near Cardigan (west Wales)

Abstract

AbstractOn the southwest‐facing slopes of a bedrock ridge lying between Cardigan Bay to the north and the Afon Teifi to the south stands a group of hills in which 30‐35 m of cross‐laminated and parallel‐laminated sands with lenticular upward‐fining gravel sequences are overlain by 10‐12 m of gravel in a single foreset bed. The sediments mantle a surface of till sloping gently toward the southwest, were transported toward the southwest (across one margin of the Afon Teifi valley), and were cut by a system of densely arranged conjugate normal faults striking northwest‐southeast.The lenticular gravels and fault system suggest that the deposits accumulated as a glaciofluvial outwash spread, and on top of an ice‐lobe that became isolated in the Teifi valley during the downwasting of a glacier which had occupied Cardigan Bay and much of the country to the south. The large gravel foresets capping the succession are the only indication at Banc‐y‐Warren of the former existence of a lake, but neither a large nor deep body of water need be envisaged.