Thursday, 22 May 2008

Paraglacial slope evolution in the Karakoram Mountains

Massive volumes of unconsolidated slope deposits on the flanks of glaciated valleys in the Karakoram Mountains are interpreted by Iturrizaga (2008) as being largely controlled by moraine re-working and mass movement induced by glacial processes. Production of debris due to weathering processed is deemed to be relatively insignificant. Talus cones that are traditionally viewed as having a periglacial origin are re-interpreted as landforms controlled by glacial activity. This paper is one of a growing number that has focussed attention on the important role of paraglacial processes on landform evolution in glacial environments. The image shows debris flanked slopes in Fåbergstølsdal, Norway, also interpreted by Ballantyne and Benn (1996) as being of paraglacial origin.

Ballantyne, C. K. and Benn, D. I. (1996). Paraglacial slope adjustment during recent deglaciation and its implications for slope evolution in formerly glaciated environments. In: M. G. Anderson and S. M. Brooks (eds). Advances in Hillslope Processes, John Wiley and Sons, Chichester. Volume 2, 1173-1195.
Iturrizaga, L. (2008). Paraglacial landform assemblages in the Hindukush and Karakoram Mountains. Geomorphology 95(1-2), 27-47.

Tuesday, 20 May 2008

Stone runs in the Falkland Islands: Periglacial or tropical?

Excavations of blockstreams (‘stone runs’) on the Falkland Islands reveal an inverted weathering profile that may be indicative of a tropical, rather than periglacial origin for these features. Apparent accumulations of blocks may, in fact, represent the in situ, regolith-stripped remnant of a Tertiary surface. A multi-phase evolution is presented by André et al (2008), that includes chemical weathering, mantle stripping, mass movement and soil forming processes. It is accepted that these polygenetic landforms may have undergone re-working and weathering by subsequent periglacial activity during the late stage Quaternary. The image shows blockstreams on Hardangervidda in Norway (Photo: DTN). For further details, read the full paper:

André, M-F., Hall, K., Bertran, P. and Arocena, J. (2008). Stone runs in the Falkland Islands: Periglacial or tropical? Geomorphology 95(3-4), 524-543.