Thermal conditions beneath parts of the last Cordilleran Ice Sheet near its centre as inferred from subglacial till, associated sediments, and bedrock

Superimposition of ribbed moraines on a palaeo‐ice‐stream bed: implications for ice stream dynamics and shutdown

“…The presence of stones adjacent to the prominent fractures that are oriented with their a-axis transverse to the inferred ice flow direction suggests that the ice was undergoing compressional flow during this phase. Stone a-axis fabric transverse to the ice flow direction has been associated with compressive flow in till in several other studies (e.g., Boulton 1971;Stanford and Mickelson, 1985;Hicock, 1990, Hart, 1994Lian and Hicock, 2000). Dreimanis (1988) also notes that that the presence of a transverse fabric mode in lodgement tills can be associated with folding and shearing of the till matrix (a consequence of compression) and that it can be used as a criterion for its identification.…”

“…These data were used together to infer the genesis of the diamicton (e.g. Krüger, 1984;Stanford and Mickelson, 1985;Hicock and Dreimanis, 1985;Dreimanis, 1993;Hart, 1994;Lian and Hicock, 2000;Lian et al, 2003).…”

Deglaciation of the Cordillera of Western Canada at the end of the Pleistocene

“…These ice divides were subordinate to the main divide along the axis of the Coast Mountains. Although there may have been localized areas of cold ice at the base of the Cordilleran Ice Sheet, especially at high elevations where the ice was relatively thin, the ice sheet was dominantly warm-based (Lian and Hicock, 2000).…”

Glacial imprints of the Okanogan Lobe, southern margin of the Cordilleran Ice Sheet

“…Criteria for identification of till types and the perceptions regarding the genesis of subglacial diamictons are given by Boulton and Hindmarsh (1987), Dreimanis (1989), Boyce and Eyles (1991), Hicock and Dreimanis (1992), Paterson (1994), Boulton (1996), Hicock et al (1996), Benn and Evans (1996), Ruszczyń ska- Szenajch (2001) and Lian et al (2003). In the context of our study, the latest assessment of the subglacial till and associated sediments indicates that central parts of the CIS in Canada experienced fast ice flow and progressive changes in thermal conditions at the glacier bed during glaciation (Lian and Hicock, 2000;Lian et al, 2003). Additionally, recent analysis JOURNAL OF QUATERNARY SCIENCE of glacial depositional features in British Columbia and the Scablands erosional architecture suggests that many of the Missoula floods may have come from subglacial outbursts from the CIS (Shaw et al, 1999) and this has fueled recent debate on the source of the meltwater (Atwater et al, 2000;Komatsu et al, 2000;Shaw et al, 2000).…”