The Tolsta Interstadial, Scotland: correlation with D–O cycles GI-8 to GI-5?

Abstract

Organic sediments, buried by till, at Tolsta Head, in north Lewis in the Scottish Outer Hebridean islands have been re-investigated. Radiocarbon dates of 32–26 kyr BP indicate correlation with the Denekamp Interstadial of The Netherlands and the Sandnes/Ålesund Interstadial of Norway. The organic sediments contain an unusually detailed record of the dominantly open grassland vegetation during the interstadial. Variations in palaeotemperature inferred from the pollen assemblages and sedimentology are provisionally matched with the δ 18O record of the GISP2 ice core and correlation with the Dansgaard–Oeschger cycles GI-8–GI-5 is proposed. The interstadial starts at 38.1k cal yr and 32.8k radiocarbon years. The termination of the interstadial and the build-up of the Late Devensian (Weichselian) ice sheets in Scotland and North West Europe dates from 32k cal yr and 28.7k radiocarbon years. Whether the Tolsta and other contemporaneous episodes are intervals or interstadials is also considered.