Snow-avalanche boulder fans in Jotunheimen, southern Norway: Schmidt-hammer exposure-age dating, geomorphometrics, dynamics and evolution

Matthews, John A, Haselberger, Stefan, Owen, Geraint, Winkler, Stefan, Hiemstra, John F, Hallang, Helen and Hill, Jennifer L ORCID: 0000-0002-0682-783X (2020) Snow-avalanche boulder fans in Jotunheimen, southern Norway: Schmidt-hammer exposure-age dating, geomorphometrics, dynamics and evolution. Geografiska Annaler: Series A, Physical Geography, 102 (2). pp. 118-140. doi:10.1080/04353676.2020.1762365

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Abstract

Eleven snow-avalanche boulder fans were dated from two high-alpine sites in Jotunheimen using Schmidt-hammer exposure-age dating (SHD) and lichenometry. Average exposure ages of the surface boulders ranged from 2285 ± 725 to 7445 ± 1020 years and demonstrate the potential of SHD for dating active landforms and diachronous surfaces. Application of GIS-based morphometric analyses showed that the volume of rock material within 10 of the fans is accounted for by 16-68 % of the combined volume of their respective bedrock chutes and transport zones. It is inferred that the fans were deposited entirely within the Holocene, mainly within the early- to mid Holocene, by frequent avalanches carrying very small debris loads. Relatively small transport-zone volumes are consistent with avalanches of low erosivity. Excess chute volumes appear to represent subaerial erosion in the Younger Dryas and possibly earlier. Debris supply to the fans was likely enhanced by early-Holocene paraglacial processes following deglaciation, and by later permafrost degradation associated with the mid-Holocene Thermal Maximum. The latter, together with the youngest SHD age from one of the fans, may presage a similar increase in geomorphic activity in response to current warming trends.

Item Type: Article
Article Type: Article
Uncontrolled Keywords: Snow avalanche boulder fans; Schmidt hammer exposure age dating; High alpine permafrost degradation; Paraglaciation; Periglacial geomorphology; Holocene
Subjects: G Geography. Anthropology. Recreation > GB Physical geography
G Geography. Anthropology. Recreation > GE Environmental Sciences
Divisions: Professional Services > Academic Development Unit
Research Priority Areas: Environmental Dynamics & Governance
Depositing User: Rhiannon Goodland
Date Deposited: 19 Mar 2020 13:03
Last Modified: 15 Jun 2020 09:45
URI: http://eprints.glos.ac.uk/id/eprint/8240

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