Age assessment and implications of late Quaternary periglacial and paraglacial landforms on Muckish Mountain, northwest Ireland, based on Schmidt-hammer exposure-age dating (SHD)

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• 作者：Peter Wilson^a ; ^{P.Wilson@Ulster.ac.uk" class="auth_mail" title="E-mail the corresponding author} ; John A. Matthews^b ; ^{J.A.Matthews@Swansea.ac.uk" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Schmidt-hammer exposure-age dating (SHD) ; Periglacial and paraglacial landforms ; Holocene climate variability ; Maritime periglacial environment ; Northwest Ireland
• 刊名：Geomorphology
• 出版年：2016
• 出版时间：1 October 2016
• 年：2016
• 卷：270
• 期：Complete
• 页码：134-144
• 全文大小：1536 K

文摘

Schmidt-hammer exposure-age dating (SHD) was applied to a variety of late Quaternary periglacial and paraglacial landforms composed of coarse rock debris on Muckish Mountain, northwest Ireland. Landform ages were determined using a linear high-precision age-calibration curve, derived from young and old control surfaces of known age on the same rock type. The SHD ages represent maximum estimates of the time elapsed since the boulders stabilised and the landforms became inactive. Most ages are also minimum estimates for the start of landform development because older boulders are buried beneath the sampled surface boulders. Ages and 95% confidence intervals obtained for blockfield, boulder lobes and talus indicate these features were likely active during several of the early Holocene cold events evidenced in Greenland ice cores and North Atlantic sediment records. Activity ceased at different times ~ 9–7 ka BP. These landforms are the first indication of a geomorphological response to early Holocene cooling in the oceanic mountains of Ireland. Late Holocene ages, obtained for rock-slope failure run-out debris and debris cone boulders, overlap with shifts to cooler and/or wetter conditions, including the Little Ice Age. Geomorphological impacts associated with these changes in climate have not previously been recorded in the Irish uplands. The SHD results indicate that previously implied timings for the stabilisation of some accumulations of coarse rock debris on mountain slopes are in need of revision.