Pleistocene depositional history in a periglacial terrane: A 500 k.y. record from Kents Cavern, Devon, United Kingdom

Abstract

The signifi cance of the stratigraphic record in Kents Cavern, Devon, United Kingdom, to the interpretation of the British Quaternary is confi rmed on the basis of a thorough reexamination of the deposits in concert with 2 new Al-Be cosmogenic and 34 new thermal ionization mass spectrometry U-Th dates. The deposits show evidence of complex reworking in response to periglaciation, and the main fl owstone deposit is a multilayered complex spanning marine isotope stage (MIS) 11-3. The lowermost unit of fl uvial sands is Cromerian or older. The second deposit, a muddy breccia of surfi cial periglacial solifl uction material containing Acheulian artifacts, entered the cave during MIS 12 from highlevel openings to the west. Cave bears denned in the cave during MIS 11, the Hoxnian interglacial; their bones are capped by an MIS 11 calcite fl owstone layer. From MIS 11 onward, each interglacial period and the warmer interstadial periods (MIS 11, 10b, 9, 7, 6b, 5, and 3) produced calcite fl owstone deposition in the cave; MIS 9 was particularly active. Each glacial or stadial period (MIS 10c, 10a, 8, 6c, 6a, 4, and 2) caused periglacial activity in the cave, during which the thinner layers of calcite were fractured by frost heave and redistributed by solifl uction. This sequence was interrupted during MIS 3-2 with the introduction of sandy and stony clastic sediments from entrances to the east, and fi nally cemented by the uppermost layer of MIS 1 fl owstone. This is the fi rst publication of welldated and clearly documented evidence of frost heaving in interior cave passages. The Kents Cavern record of continuous, repeated sedimentation events followed by frost shattering and remobilization events over the past 500 k.y. is probably unique in the karst literature and establishes Kents Cavern as a site of international scientifi c interest.