Iceberg calving and the glacioclimatic record

Warren, Charles R.

doi:10.1177/030913339201600301

Cited by 82 publications

(64 citation statements)

References 146 publications

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“…More subtle variations in bed topography can also exert a control on moraine formation, through an impact on glacier mass balance and margin stability (here, the focus is on land-terminating glaciers, whilst lake-and marine-terminating glaciers are considered in section 3.3.4) (Oerlemans, 1989;Warren and Hulton, 1990;Warren, 1991Warren, , 1992Kerr, 1993). For example, where bed topography is comparatively shallow, glaciers typically have correspondingly low surface gradients and are therefore sensitive to climate forcing (Oerlemans, 1989).…”

Section: Bed Slopes Glacier Mass Balance and Ice Margin Stabilitymentioning

confidence: 99%

“…In the case of lake-and marine-terminating glaciers, ablation is dominated by calving, and ice mass stability (or lack thereof) is dictated by the position of the grounding-line where moraines are generated (Warren, 1992;Benn et al, 2007;Schoof, 2007). Calving glaciers are prone to fluctuations, but stability is typically favoured where the calving front is comparatively small (i.e., ablation is limited); where the terminus is grounded; and/or where basaldrag, lateral drag, and backstress are comparatively high (O'Neel et al, 2005;Benn et al, 2007).…”

Section: Fjord Topographymentioning

confidence: 99%

“…Calving glaciers are prone to fluctuations, but stability is typically favoured where the calving front is comparatively small (i.e., ablation is limited); where the terminus is grounded; and/or where basaldrag, lateral drag, and backstress are comparatively high (O'Neel et al, 2005;Benn et al, 2007). Topography (fjord/trough geometry) plays a key role in governing these factors and is therefore fundamental to the stability of lake-and marine-terminating glaciers (more so than in the case of land-terminating examples) (Warren and Hulton, 1990;Warren, 1991Warren, , 1992. In particular, topographic pinning points represent potentially stable locations where moraine formation can occur (Warren, 1991;O'Neel et al, 2005;Jamieson et al, 2012Jamieson et al, , 2014Carr et al, 2013).…”

Section: Fjord Topographymentioning

confidence: 99%

“…In particular, topographic pinning points represent potentially stable locations where moraine formation can occur (Warren, 1991;O'Neel et al, 2005;Jamieson et al, 2012Jamieson et al, , 2014Carr et al, 2013). These pinning points often consist of laterally confined shallow basins, subaerial topographic obstructions (i.e., islands) or bathymetric highs (such as the adverse slopes of overdeepenings) (Warren and Hulton, 1990;Warren, 1991Warren, , 1992Cook and Swift, 2012). During retreat from stable locations into wider/deeper sections of troughs and/or away from islands or bathymetric highs, ablation will increase significantly (perhaps enhanced by the incursion of warm water into previously enclosed basins -see Jenkins et al, 2010), and glaciers will undergo rapid retreat until the next topographic pinning point is reached (Warren and Hulton, 1990;Boyce et al, 2007;Nick et al, 2009;Jamieson et al, 2012;Carr et al, 2013).…”

Section: Fjord Topographymentioning

confidence: 99%

“…15) indicate that the ice stream experienced several retreat rate slowdowns (i.e., grounding-line stabilisations) at notable topographic highs and on reverse bed slopes (where lateral drag was enhanced at trough narrowings) (Jamieson et al, 2012). Since grounding-line stability is key to moraine formation, these topographic controls are generally considered to result in the preferential deposition of moraines (and grounding-zone wedges) in proximity to valley narrowings (i.e., associated with the transition to wider locations where calving is increased: Mercer, 1961;Funder, 1972); bends; bifurcations; where basins are shallow; and/or in the vicinity of topographic bumps (Warren and Hulton, 1990;Warren, 1991Warren, , 1992. When lake-or marine-terminating glaciers retreat on to land (up a bedrock slope or prominent step), they often experience margin stabilisation, or even slight advance, as calving ceases Occhietti, 1977, 1980;Hillaire-Marcel et al, 1981;Funder, 1989;Warren and Hulton, 1990;Warren, 1991).…”

Section: Fjord Topographymentioning

confidence: 99%

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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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