Late-glacial mean July air temperature inferred from midge species (a) at Whitrig Bog, southeast Scotland (from Brooks & Birks, 2000a) compared to the GRIP oxygen isotope data (b).
Diagram from CICERO - the Centre for International Climate and Environmental Research in Oslo
The late-glacial stratigraphy of northwest Europe (after Roberts, 1998)
Definition: the period between deglaciation and the start of the Holocene.
Marine sediments show that a weak North Atlantic Drift became established off Western Scotland and in the Norwegian and North Sea by 12,800 radiocarbon years BP. On Shetland the oldest radiocarbon dates from lake basins lie at around this date. If these radiocarbon dates are correct and not affected by hard water errors then Shetland must have been largely free of glacier ice by 15.8–14.4 cal ka. The Greenland ice core data indicate that the amelioration was remarkably rapid, possibly occurring within 50 years.
The timing of deglaciation probably varied across Shetland. The outlying islands were probably first to emerge and then ice progressively disappeared from the hills of Mainland. Various ice marginal positions have been identified, including moraines and ice-dammed lakes on Unst (Flinn, 1983, 1991) and Papa Stour (Mykura and Phemister, 1976). Lake sediments containing organic materials at Aith Voe, Lang Lochs and Clettnadal have been dated to 12.8-13 radiocarbon ka and indicate that low ground was ice-free and vegetated prior to this. Temperatures rose close to present values and a complex mosaic of vegetation communities developed.
After 11.5 ka the warm phase started to deteriorate and there was a return to arctic conditions around 11 ka radiocarbon years BP. The Loch Lomond Stadial was a highly significant interval in the development of the scenery of Scotland. Small glaciers may have returned to Shetland for the final time, although firm evidence from the dating of moraines is still awaited. Permafrost could have become established on both high and low ground but, again, there is little firm evidence of former permafrost ob Shetland during this interval. This intensely cold phases terminated around 10,000 years ago with the onset of Holocene warming.