Abstract
We present 17 cosmogenic 10Be ages of glacial deposits in Coire an Lochain (Cairngorm Mountains), which demonstrate that glacial and nival deposits cover a longer timescale than previously recognised. Five ages provide the first evidence of a late-Holocene glacier in the British Isles. A previously unidentified moraine ridge was deposited after c. 2.8 kyr and defines a small slab-like glacier with an equilibrium line altitude (ELA) at c. 1047 m. The late-Holocene glacier was characterised by rapid firnification and a dominance of sliding, enabling the glacier to construct moraine ridges in a relatively short period. Isotopic inheritance means that the glacier may have existed as recently as the ‘Little Ice Age’ (LIA) of the 17th or 18th century ad, a view supported by glacier-climate modelling. Nine 10Be ages confirm a Younger Dryas Stadial (YDS) age for a cirque-floor boulder till, and date the glacier maximum to c. 12.3 kyr when the ELA was at c. 963 m altitude. Both glaciers existed because of enhanced accumulation from wind-blown snow, but the difference in ELA of only c. 84 m belies the YDS–LIA temperature difference of c. 7°C and emphasises the glacioclimatic contrast between the two periods. Three 10Be ages from till boulders originally deposited in the YDS yield ages <5.5 kyr and indicate snow-avalanche disturbance of older debris since the mid-Holocene, as climate deteriorated towards marginal glaciation.
Original language | English |
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Pages (from-to) | 141-148 |
Number of pages | 8 |
Journal | The Holocene |
Volume | 24 |
Issue number | 2 |
Early online date | 18 Dec 2013 |
DOIs | |
Publication status | Published - Feb 2014 |
Keywords
- beryllium 10
- Cairngorm Mountains
- cosmogenic dating
- glacier reconstruction
- 'Little Ice Age'
- Younger Dryas
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Kirkbride, Martin
- Energy Environment and Society - Honorary Senior Research Fellow (Geography)
Person: Honorary