Changes in ice‐margin processes and sediment routing during ice‐sheet advance across a marginal moraine

Abstract

: Changes in ice-margin processes and sediment routing during ice-sheet advance across a marginal moraine. Geogr. Ann., 89 A (3): 203-215.ABSTRACT. Advance of part of the margin of the Greenland ice sheet across a proglacial moraine ridge between 1968 and 2002 caused progressive changes in moraine morphology, basal ice formation, debris release, ice-marginal sediment storage, and sediment transfer to the distal proglacial zone. When the ice margin is behind the moraine, most of the sediment released from the glacier is stored close to the ice margin. As the margin advances across the moraine the potential for ice-proximal sediment storage decreases and distal sediment flux is augmented by reactivation of moraine sediment. For six stages of advance associated with distinctive glacial and sedimentary processes we describe the ice margin, the debris-rich basal ice, debris release from the glacier, sediment routing into the proglacial zone, and geomorphic processes on the moraine. The overtopping of a moraine ridge is a significant glaciological, geomorphological and sedimentological threshold in glacier advance, likely to cause a distinctive pulse in distal sediment accumulation rates that should be taken into account when glacial sediments are interpreted to reconstruct glacier fluctuations.

A morphological, sedimentological and geophysical investigation of the Woore Moraine, Shropshire, England

“…Finally, the presence of a prominent hill-crest is thought to represent the former position of the icemargin (Sadura et al, 2006). The lack of a prominent hill-crest (profile 1; figure 3) and a change in gross-geomorphology in the western-region of the Woore Moraine may reflect the moraine being over-ridden and reworked (Knight et al, 2007). Consequently, the scale and cross-sectional morphology of the Woore Moraine are consistent with its interpretation as a composite ridge.…”

Ice-dammed lake and ice-margin evolution during the Holocene in the Kangerlussuaq area of west Greenland

“…In consideration of a more advanced ice margin (during the 3480 ± 45 cal. yr BP time period covered by the profile) in comparison to that of today, we note that there are no moraine deposits around the shores of the lake, and the only moraine ridges on the northern margin of Russell Glacier were formed during AD 1985 and 2000 (Knight et al 2000(Knight et al , 2007.…”

The Arctic in the Twenty-First Century: Changing Biogeochemical Linkages across a Paraglacial Landscape of Greenland

“…The ice-sheet margin at Kangerlussuaq has recently experienced a period of thickening (1980–2000), followed by rapid ice-marginal thinning and recession of outlet glaciers (Knight et al, 2007). Two of the most prominent glacier changes have been the evolution of supraglacial lakes and the reoccurrence of drainage outbursts from a large ice-dammed lake.…”