Palaeoclimatic reconstruction from Lateglacial (Younger Dryas Chronozone) cirque glaciers in Snowdonia, North Wales

Bendle, Jacob; Glasser, Neil F.

doi:10.1016/j.pgeola.2011.09.006

Cited by 36 publications

(61 citation statements)

References 79 publications

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“…The ELA is therefore often used in palaeoclimate reconstructions based on the former dimensions of glaciers at their maximum extent (e.g. Ballantyne, 2002aBallantyne, , 2007aBenn and Ballantyne, 2005;Bakke et al, 2005a,b;Rea and Evans, 2007;Finlayson et al, 2011;Bendle and Glasser, 2012). Calculated palaeo-ELAs are usually referred to as steady-state ELAs since an assumption is made that the reconstructed glacier was in equilibrium with climate at the time it was at its maximum position.…”

Section: Palaeoclimate During the Younger Dryasmentioning

confidence: 99%

“…This relationship allows either temperature or precipitation to be calculated if an independent value is known for the other. It has been used extensively to derive palaeoprecipitation at the ELA of former glaciers in combination with an independent temperature proxy (Kerschner et al, 2000;Carr, 2001;Bendle and Glasser, 2012), usually derived as mean July temperatures inferred from subfossil chironomids assemblages, for Scottish Younger Dryas glaciers (e.g. Benn and Ballantyne, 2005;Finlayson et al, 2011).…”

Section: Palaeoclimate During the Younger Dryasmentioning

confidence: 99%

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A Younger Dryas plateau icefield in the Monadhliath, Scotland, and implications for regional palaeoclimate

Boston

Lukas

Carr

2015

Quaternary Science Reviews

136

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a b s t r a c tA record of Younger Dryas glaciation in Scotland is well established. However, the role of the Monadhliath, a significant plateau area extending over 840 km 2 in central Scotland, has never been investigated systematically. We present the first systematic glacial geomorphological mapping across the whole region, which has led to the identification of hitherto-unrecorded glacial and associated landforms. The spatial distribution of these landforms indicates that the last phase of glaciation in the area was that of a local plateau icefield. In addition, a clear morphostratigraphical signature provides a strong indication that the icefield dates to the Younger Dryas (12.9e11.7 ka), which is supported by numerical ages in the southeast of the study area. Based on the geomorphological evidence and 2D glacier surface profile modelling, a 280 km 2 icefield is reconstructed. A novel approach is introduced to quantify plateau icefield thickness for equilibrium line altitude (ELA) and palaeoprecipitation calculations, resulting in greater overall data confidence compared to traditional reconstruction methods. The ELA for the whole icefield is calculated to be 714 ± 25 m, whilst the ELAs of individual outlet glaciers range from 560 m in the west to 816 m in the east, demonstrating a significant WeE precipitation gradient across the region during the Younger Dryas. These ELAs compare well with those calculated for Younger Dryas ice masses reconstructed in neighbouring regions and are in good agreement with overall precipitation patterns suggested for Scotland during this time. Whilst the total amount of precipitation calculated from these ELAs is highly dependent on the method used, irrespective of this, the study suggests a more arid Younger Dryas climate in the region compared to the present day.

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Section: Palaeoclimate During the Younger Dryasmentioning

confidence: 99%

Section: Palaeoclimate During the Younger Dryasmentioning

confidence: 99%

A Younger Dryas plateau icefield in the Monadhliath, Scotland, and implications for regional palaeoclimate

Boston

Lukas

Carr

2015

Quaternary Science Reviews

136

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“…There is a clear predominance of glaciers with northerly to easterly aspects (Bendle & Glasser, 2012;Shakesby, 2007), which offer protection from insolation and are sites with a higher potential to receive nourishment of windblown snow from the west. This is particularly the case when plateau or upland areas are found immediately southwest of the glacier, in the direction of the predominant winds.…”

Section: Discussionmentioning

confidence: 99%

The glacial geomorphology of the Loch Lomond Stadial in Britain: a map and geographic information system resource of published evidence

et al. 2016

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The Loch Lomond Stadial (LLS) was an abrupt period of renewed cooling between 12.9 and 11.7 ka and has long been associated with the regrowth of glaciers in much of upland Britain. Mapping the glacial landforms associated with this period has been undertaken for over a century, but in a non-systematic nature and at specific locations. In this paper, glacial geomorphology associated with the LLS in Britain has been compiled from the published literature into a glacial map and accompanying geographical information system database that is available electronically as supplementary information. A variety of scales have been used to best represent the evidence in the database. Map A is at 1:310 000; B, C, D, E, F, J, L, M and O are at 1:175 000; K, N, P are at 1:100 000 and G, H and I are at 1:50,000. The database contains over 95,000 individual features, which are organised into thematic layers and each attributed to its original citation. The evidence includes moraines, drift and boulder limits, drift benches, periglacial trimlines, meltwater channels, eskers, striations and roches moutonneés, protalus ramparts and ice-dammed lakes. Creation of this database overcomes the drawbacks posed by the non-systematic nature of previous mapping output from studies of LLS glaciation. It is intended to be a catalyst for future research in this area, with especial significance for regional palaeoglaciological and palaeoclimatic reconstructions of the Younger Dryas and numerical modelling. ARTICLE HISTORY

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“…The distribution and dimensions of cirque glaciers are strongly controlled by topography (Mills et al, 2009;Bendle and Glasser, 2012). For the purpose of this paper, a distinction is made between topoclimatic factors (such as aspect, which regulates the receipt of solar radiation or allows snow to accumulate in the lee of prevailing winds), which directly impact local climatic conditions, and topographic factors (such as ice and snow avalanching from surrounding peaks), which regulate glacier size without a direct impact on local climate.…”

Section: Controls On Moraine Formationmentioning

confidence: 99%

“…However, in reality, even when such reconstructions are generated, topographic factors continue to introduce uncertainty and limit the validity of resulting palaeoclimatic data. One key limitation stems from the fact that palaeoglacier reconstructions often rely on directly dating a small number of moraines and extrapolating these age-estimates to a wider population of landforms (e.g., Finlayson et al, 2011;Bendle and Glasser, 2012;Nawaz Ali et al, 2013). This approach relies on chronologically grouping moraines that are assumed to have been deposited synchronously.…”

Section: Can Uncertainty Introduced By Topographic Controls Be Mitigamentioning

confidence: 99%

A review of topographic controls on moraine distribution

2014

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Ice-marginal moraines are often used to reconstruct the dimensions of former ice masses, which are then used as proxies for palaeoclimate. This approach relies on the assumption that the distribution of moraines in the modern landscape is an accurate reflection of former ice margin positions during climatically controlled periods of ice margin stability. However, the validity of this assumption is open to question, as a number of additional, nonclimatic factors are known to influence moraine distribution. This review considers the role played by topography in this process, with specific focus on moraine formation, preservation, and ease of identification (topoclimatic controls are not considered). Published literature indicates that the importance of topography in regulating moraine distribution varies spatially, temporally, and as a function of the ice mass type responsible for moraine deposition. In particular, in the case of ice sheets and ice caps ( > 1000 km 2 ), one potentially important topographic control on where in a landscape moraines are deposited is erosional feedback, whereby subglacial erosion causes ice masses to become less extensive over successive glacial cycles. For the marine-terminating outlets of such ice masses, fjord geometry also exerts a strong control on where moraines are deposited, promoting their deposition in proximity to valley narrowings, bends, bifurcations, where basins are shallow, and/or in the vicinity of topographic bumps. Moraines formed at the margins of ice sheets and ice caps are likely to be large and readily identifiable in the modern landscape. In the case of icefields and valley glaciers (10-1000 km 2 ), erosional feedback may well play some role in regulating where moraines are deposited, but other factors, including variations in accumulation area topography and the propensity for moraines to form at topographic pinning points, are also likely to be important. This is particularly relevant where land-terminating glaciers extend into piedmont zones (unconfined plains, adjacent to mountain ranges) where large and readily identifiable moraines can be deposited. In the case of cirque glaciers (< 10 km 2 ), erosional feedback is less important, but factors such as topographic controls on the accumulation of redistributed snow and ice and the availability of surface debris, regulate glacier dimensions and thereby determine where moraines are deposited. In such cases, moraines are likely to be small and particularly susceptible to post-depositional modification, sometimes making them difficult to identify in the modern landscape. Based on this review, we suggest that, despite often being difficult to identify, quantify, and mitigate, topographic controls on moraine distribution should be explicitly considered when reconstructing the dimensions of palaeoglaciers and that moraines should be judiciously chosen before being used as indirect proxies for palaeoclimate (i.e., palaeoclimatic inferences should only be drawn from moraines when topographic controls on mora...

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Palaeoclimatic reconstruction from Lateglacial (Younger Dryas Chronozone) cirque glaciers in Snowdonia, North Wales

Cited by 36 publications

References 79 publications

A Younger Dryas plateau icefield in the Monadhliath, Scotland, and implications for regional palaeoclimate

A Younger Dryas plateau icefield in the Monadhliath, Scotland, and implications for regional palaeoclimate

The glacial geomorphology of the Loch Lomond Stadial in Britain: a map and geographic information system resource of published evidence

A review of topographic controls on moraine distribution

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