Premium
Morphology and surface structures of Maxwell Creek rock glaciers, St Elias mountains, Yukon: rheological implications
Author(s) -
Johnson P. G.
Publication year - 1998
Publication title -
permafrost and periglacial processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.867
H-Index - 76
eISSN - 1099-1530
pISSN - 1045-6740
DOI - 10.1002/(sici)1099-1530(199801/03)9:1<57::aid-ppp275>3.0.co;2-g
Subject(s) - geology , moraine , rock glacier , glacier , geomorphology , landform , tributary , mass movement , glacier morphology , ice stream , cryosphere , climatology , landslide , sea ice , cartography , geography
The dominant role of mass movement processes in the formation of south‐west Yukon paraglacial landscapes is exemplified by a tributary of Maxwell Creek. Rock glaciers occur along most of the length of the mid‐valley. Two large rock glaciers flowing from cirques on the east and west sides of the valley are confluent in the centre of the valley, and have a combined lobe extending 1 km downvalley. Morphological contrasts between the moraines and flow lobes of the east form, and the flow ridges of the west form, indicate different processes of movement at the surface. Sections in the surface deposits indicate movement of the mass of material in the lobes but demonstrate a combination of overriding and compression flow in the ridges. Near surface composition varies from large boulders with voids, to boulders with gravel and fines matrix and with the ice content varying from interstitial to massive infilling of the voids. Palaeosols sampled 1 m underneath overriding ridges were dated at 1480 and 660 a BP . The rock glaciers produced a combined central valley landform at the end of the Wisconsin. Neoglacial activity resulted only in confluence of the rock glaciers, without extension downvalley. The combination of the compressional and overriding ridges with the variability of the sediments and ice content is indicative of a complex surface rheology. Comparison with the ridges and lobes of rock glaciers in other valleys suggests that this surface variability is common on the rock glaciers of the southwest Yukon. © 1998 John Wiley & Sons, Ltd.