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Titel |
Unravelling Younger Dryas glaciation in the Tweedsmuir Hills, Southern Uplands, Scotland. |
VerfasserIn |
Danni Pearce, Brice Rea, Iestyn Barr, Jeremy Everest, Nick Primmer, Pete Langdon, Mary Edwards, Des McDougall |
Konferenz |
EGU General Assembly 2013
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 15 (2013) |
Datensatznummer |
250082955
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Zusammenfassung |
In Britain, the glacial geomorphological record has been widely utilised to infer
palaeo-glacier geometries and ice dynamics with much of this work focussing on the Scottish
Highlands during the Last Glacial Interglacial Transition (LGIT), in particular the Younger
Dryas (YD; c. 12.9 – 11.7 ka BP). The Southern Uplands represents the largest upland area
south of the Highlands but have received limited research attention over the last
century.
The Tweedsmuir Hills are located in the central Southern Uplands, which form an area of
dissected plateau approximately 320 km2. Early research in the 1800s identified a range of
glacial landforms thought to be associated with the YD. The majority of previous work has
focussed on isolated valleys and ignored the potential for plateau icefield glaciation, which
has significant implications for understanding of the dynamics and geometries of the YD ice
masses. Recent numerical modelling experiments covering the period 38 - 10.4 ka
BP (Hubbard et al., 2008 cf. E109B8 and E102b2) have predicted a significant
body of ice for the Southern Uplands at the onset of and throughout the YD, which
cannot be verified at present due to a lack of empirical data. This research aims to
provide the first systematic mapping and climate reconstruction for the Tweedsmuir
Hills.
The results of air-photo interpretation and field mapping, which utilised a
morphostratigraphic approach, has demonstrated a more extensive glaciation than previously
mapped. This consists of two separate icefields over the southern and northern Tweedsmuir
Hills which cover an area c. 45 km2 and 25 km2 respectively with Equilibrium Line Altitudes
(ELAs) calculated to have ranged from c. 419 m to 634 m. For both icefields ELAs of
individual outlets reflect topographic controls rather than steep precipitation gradients like
those derived for other icefields in Scotland (e.g., the Monadhliath Mountains and Beinn
Dearg). New radiocarbon dating of basal stratigraphies and Terrestrial Cosmogenic
Nuclide Analysis (TCNA) of in situ boulders data place the icefields within the
context of the YD. Landform evidence also indicates smaller valley glaciers occupied
some of the south-easterly catchments until the end of the YD. All of these results
differ significantly from the traditional paradigm which suggests that due to low
accumulation, only restricted ice masses developed in the Tweedsmuir Hills during this
time.
References: Hubbard, A. et al., (2009). Dynamic cycles, ice streams and their impact on
the extent, chronology and deglaciation of the British–Irish ice sheet. Quaternary Science
Reviews, (28), 7–8, 758-776 |
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