<scp>BRITICE</scp> Glacial Map, version 2: a map and <scp>GIS</scp> database of glacial landforms of the last British–Irish Ice Sheet

Clark, Chris D.; Ely, Jeremy C.; Greenwood, Sarah L.; Hughes, Anna L.C.; Meehan, Robert; Barr, Iestyn D.; Bateman, Mark D.; Bradwell, Tom; Doole, Jenny; Evans, David J. A.; Jordan, Colm; Monteys, Xavier; Pellicer, Xavier M.; Sheehy, Michael

doi:10.1111/bor.12273

Cited by 117 publications

(121 citation statements)

References 264 publications

(313 reference statements)

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“…Both modelling studies and observations show that the last British–Irish Ice Sheet (BIIS) was a dynamic and rapidly changing ice mass (Hubbard et al ., ; Chiverrell et al ., ; Patton et al ., ,,; Clark et al ., ). Scourse et al .…”

Section: Introductionmentioning

confidence: 99%

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Late Devensian deglaciation of south‐west Wales from luminescence and cosmogenic isotope dating

Glasser

Davies

Hambrey

et al. 2018

J Quaternary Science

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The Welsh Ice Cap was a dynamic component of the last British–Irish Ice Sheet at the Last Glacial Maximum, but there are few chronological constraints on the pace and timing of deglaciation. This paper presents new geomorphological and geochronological evidence that constrains the timing of the separation of the Welsh Ice Cap from the Irish Sea Ice Stream and the subsequent deglaciation of south‐west Wales; and allow these to be assessed in the context of late Pleistocene climatic events. Luminescence ages from glacial outwash sediments south of Cardigan demonstrate that the Irish Sea Ice Stream was receding by ∼26.7 ka. The subsequent recession of the Welsh Ice Cap is documented by cosmogenic ages from landforms and sediments in the Aeron and Teifi valleys and upland areas. Deglaciation of the Cambrian Mountains was underway by ∼19.6 ka. Cross‐valley moraines and associated deglaciation deposits show that minor re‐advances interrupted the recession of the Aeron Glacier twice, and the Teifi Glacier on at least 12 occasions. By ∼14.9 ka, the Aeron valley was probably ice‐free, but the northwards withdrawal of the Teifi glacier had halted in the Tregaron area. The final rapid recession of this glacier into the uplands of central Wales was completed during the Windermere Interstadial (13.5 cal ka BP) when, in common with much of the UK, the whole of Wales is believed to have become ice‐free. There is no evidence that the Cambrian Mountains contained ice‐free enclaves at the Last Glacial Maximum, as has been previously suggested. The new ages presented here support suggestions that there was rapid change in the configuration of the Welsh Ice Cap between 20 and 17 ka as upland areas became exposed and there was increasing topographic control on patterns of ice discharge.

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Section: Introductionmentioning

confidence: 99%

“…Clark et al (, ) and Hughes et al . (, ) provided comprehensive reviews of the geochronological evidence for the glaciation in the British Isles and concluded that the BIIS reached its maximum extent at different times in different sectors.…”

Section: Introductionmentioning

confidence: 99%

Late Devensian deglaciation of south‐west Wales from luminescence and cosmogenic isotope dating

Glasser

Davies

Hambrey

et al. 2018

J Quaternary Science

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“…This work focuses on all recognizable ( n = 2208) cirques in Britain and Ireland that were mapped from remotely sensed data (Barr et al, ; Clark et al, ). For each cirque, length ( L ), width ( W ) and depth ( H ) are calculated using ACME, a dedicated GIS tool (Spagnolo et al, ) (Figure ).…”

Section: Methodsmentioning

confidence: 99%

The dynamics of mountain erosion: Cirque growth slows as landscapes age

Barr

Ely

Spagnolo

et al. 2019

Earth Surf Processes Landf

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Glacial cirques are widely used palaeoenvironmental indicators, and are key to understanding the role of glaciers in shaping mountain topography. However, notable uncertainty persists regarding the rate and timing of cirque erosion. In order to address this uncertainty, we analyse the dimensions of 2208 cirques in Britain and Ireland and model ice accumulation to investigate the degree of coupling between glacier occupation times and cirque growth. Results indicate that during the last ~120 ka, cirques were glacier‐free for an average of 52.0 ± 21.2 ka (43 ± 18%); occupied by small (largely cirque‐confined) glaciers for 16.2 ± 9.9 ka (14 ± 8%); and occupied by large glaciers, including ice sheets, for 51.8 ± 18.6 ka (43 ± 16%). Over the entire Quaternary (i.e. 2.6 Ma), we estimate that cirques were glacier‐free for 1.1 ± 0.5 Ma; occupied by small glaciers for 0.3 ± 0.2 Ma; and occupied by large glaciers for 1.1 ± 0.4 Ma. Comparing occupation times to cirque depths, and calculating required erosion rates, reveals that continuous cirque growth during glacier occupation is unlikely. Instead, we propose that cirques attained much of their size during the first occupation of a non‐glacially sculpted landscape (perhaps during the timeframe of a single glacial cycle). During subsequent glacier occupations, cirque growth may have slowed considerably, with the highest rates of subglacial erosion focused during periods of marginal (small glacier) glaciation. We propose comparatively slow rates of growth following initial cirque development because a ‘least resistance’ shape is formed, and as cirques deepen, sediment becomes trapped subglacially, partly protecting the bedrock from subsequent erosion. In support of the idea of rapid cirque growth, we present evidence from northern British Columbia, where cirques of comparable size to those in Britain and Ireland developed in less than 140 ka. © 2019 John Wiley & Sons, Ltd. © 2019 John Wiley & Sons, Ltd.

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“…On average, surface heat flow has increased ∼Δ q s =15 mW/m 2 after the paleoclimate correction. Regionally, Δ q s increases from 8 to 19 mW/m 2 northeast to southwest, which reflects the progressive NE retreat of the BIIS (Clark et al, ).…”

Section: Surface Heat Flow In Irelandmentioning

confidence: 99%

Probabilistic Surface Heat Flow Estimates Assimilating Paleoclimate History: New Implications for the Thermochemical Structure of Ireland

2018

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Regions where surface temperature has increased since past glaciation events, such as Ireland, underestimate the heat output of the Earth unless paleoclimate corrections are applied. We apply probabilistic techniques to quantify the uncertainty of 22 paleoclimate‐corrected heat flow estimates in Ireland, which assimilate multiple surface temperature histories associated with 130 ka of glacial oscillation in the British Isles. Heat flow values increase by ∼15 mW/m2 after a paleoclimate correction and provide new insights into the thermochemical structure of the lithosphere. The heat flow regime is broadly delineated by the Iapetus Suture Zone that separates Laurentian to the north and Avalonian terranes to the south (mean surface heat flow of 73 ± 14 and 65 ± 14 mW/m2, respectively). The degree to which heat‐producing elements are partitioned into the uppermost crust is described by the differentiation index of a heat flow province. From Bayesian inversion, we determine that radiogenic elements are substantially more differentiated in the uppermost crust of Laurentia (DI=2.8 ± 1.4) than Avalonia (DI=1.5 ± 1.3), despite a moderately enriched lower crust (0.8 ± 0.3 μW/m3). This is facilitated by a thin yet highly radiogenic layer in the uppermost crust of Laurentia (3.9 ± 1.8 μW/m3). Extrapolating these results across the British Isles and Newfoundland suggests that heat‐producing elements have been more successfully reworked into the upper crust to the north of the Iapetus Suture Zone during continental accretion between Laurentia and Avalonia.

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BRITICE Glacial Map, version 2: a map and GIS database of glacial landforms of the last British–Irish Ice Sheet

Cited by 117 publications

References 264 publications

Late Devensian deglaciation of south‐west Wales from luminescence and cosmogenic isotope dating

Late Devensian deglaciation of south‐west Wales from luminescence and cosmogenic isotope dating

The dynamics of mountain erosion: Cirque growth slows as landscapes age

Probabilistic Surface Heat Flow Estimates Assimilating Paleoclimate History: New Implications for the Thermochemical Structure of Ireland

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