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Loch Lomond StadialDefinition: Cold period that occurred towards the end of the last (Devensian) glacial stage in Scotland, equivalent to the Younger Dryas of NW Europe. The event took place about 11000-10000 radiocarbon years BP. The period is named after the advance of ice from the SW Highlands to the southern shore of Loch Lomond. For more background see hereMany questions remain about environments on Shetland during this cold interval. In Scotland, the Loch Lomond Stadial is a key interval in shaping of the landscape. In the mountains, glaciers reformed and advanced rapidly. In the lowlands, permafrost returned. Intense frost weathering generated screes and solifluction, the soil flow generated by flow of the active layer in summer, led to sludging of considerable thicknesses of glacial deposits to the base of slopes.
In Shetland, there have been long-standing
suggestions that small glaciers developed at Burn of Mail, Sandness and north of
Ronas Hill but, whilst local glaciers certainly once existed at these locations,
their moraines remain undated. Records of organic sediments in lakes point to
one or more periods cooling at around this time, with increased erosion in
catchments and sediment supply to lakes, but the detailed record at Clettnadal
points to at least three intervals when organic deposition resumed (Whittington
et al, 2003; Robinson, 2004). Three incursions of warmer water to at least latitude
56ºN during the Loch
Lomond Stadial were also detected by Kroon et al. (1997), in the offshore
sedimentary sequence near north-west Scotland. It remains possible that a weak
maritime influence prevented the development of permafrost over large parts of
Shetland at this time. The relatively milder conditions might account for the
apparently limited development of scree and solifluction deposits on Shetland. |