A revision of the British Chronostratigraphy within the Last Glacial-Interglacial Cycle based on new evidence from Arclid, Cheshire UK

Of the 24 Greenland interstadials (GI) in the Last Glacial-interglacial cycle (LGIC) only five are formally recognised in Britain. This paper aims to improve understanding of the LGIC in Britain from a site at Arclid, Cheshire. Sediments were characterised and luminescence used to establish a chronology. This found that the Chelford Sand Formation spans 77-47 ka with sand deposited initially by aeolian but later by fluvial transportation. Coleoptera and Diptera from the basal peat lens provided a reconstruction for a heather rich heathland environments grazed by large herbivores, with summer temperatures between 13-18° C, and winter temperatures between -14 and 1°C. Flies included the earliest records of the blood-sucking horsefly Haematopota fluvialis, and the soldierfly Chloromyia formosa. The overlying Stockport Sand Formation was deposited fluvioglacially between 47-41 ka with the upper Stockport Till formed by the advance of the last British icesheet after ~33 ka. Stenothermic beetle analysis from Arclid indicate similarities with results from other British mid LGIC sites, some of which are at or beyond the limit of radiocarbon dating and may be of a similar age to Arclid. A revised British chronostratigraphy places the Chelford, Brimpton and Cassington Interstadials within GI22/23, GI 21 and GI 20/19. Basal organic sediments found at Arclid are assigned to GI 17/16 with the Arclid mid and upper peats tentatively assigned to GI 14 and GI 13. This removes the gap in interstadials between the Brimpton Interstadial and the Upton Warren Interstadial complex within the British chronostratigraphy.