New evidence for active talus-foot rock glaciers at Øyberget, southern Norway, and their development during the Holocene

Bibliographic Data

ID12266285
AuthorsAtle Nesje (0000-0001-8508-5805, Department of Earth Science, University of Bergen and Bjerknes Centre for Climate Research, Norway, corresponding author), John A Matthews (0000-0002-2610-863X, Swansea University), Henriette C Linge (0000-0002-6069-5348, Department of Earth Science, University of Bergen and Bjerknes Centre for Climate Research, Norway), Marie Bredal (Geological Survey of Norway), Peter Wilson (0009-0000-6882-5883, School of Geography and Environmental Sciences, Ulster University, UK), Stefan Winkler (0000-0002-0650-1207, Department of Geography and Geology, Julius-Maximilians-University Würzburg, Germany)
Year2021
Volume31
Issue11-12
Pages1786-1796
Publication date2021-08-15
Peer ReviewedYes
Open AccessYes
TypeARTICLE
VenueThe Holocene (JOURNAL)
Journal identifiersISSN: 0959-6836 • E-ISSN: 1477-0911
PublisherSAGE Publishing (PUBLISHER • US)
DOI10.1177/09596836211033226
OpenAlexW3196092984
LanguageEN
Citations received2
References cited79

Synthetic aperture radar interferometry (InSAR) measurements demonstrate that lobate, blocky depositional landforms, located in southern Norway at an altitude of ~530 m above sea level, with an estimated mean annual air temperature of ~1.6°C, currently exhibit deformation attributed to viscous creep. Five years of InSAR measurements for six lobes demonstrate average surface velocities of 1.2–22.0 mm/year with maximum rates of 17.5–55.6 mm/year. New Schmidt-hammer exposure-age dating (SHD) of two proximal lobes reveals mid-Holocene ages (7.6 ± 1.3 ka and 6.0 ± 1.2 ka), which contrast with the early-Holocene SHD and 10 Be ages obtained previously from distal lobes, and late-Holocene SHD ages presented here from two adjacent talus slopes (2.3 ± 1.0 ka and 2.4 ± 1.0 ka). Although passive transport of boulders on the surfaces of these small, slow-moving rock glaciers affected by compressive flow means that the exposure ages are close to minimum estimates of the time elapsed since lobe inception, disturbance of boulders on rock glaciers is a source of potentially serious underestimates of rock-glacier age. Rock-glacier development at Øyberget began shortly after local deglaciation around 10 ka before present and continued throughout the Holocene in response to microclimatic undercooling within the coarse blocky surface layer of the talus and rock-glacier lobes. We suggest this enhanced cooling lowers mean annual surface-layer temperature by at least ~3.6°C, which is needed at such a low altitude to sustain sporadic permafrost and avoid fast thawing as atmospheric temperatures rise. Our results point to circumstances where inferences about rock glaciers as indicators of regional climate should be interpreted with caution, and where they may be less useful in palaeoclimatic reconstruction than previously thought

Altitude (triangle · Cirque glacier · Cryosphere · Deglaciation · Geomorphology · Glacier · Holocene · Ice stream · Landform · Moraine · Physical geography · Rock glacier · Sea ice · Sea level · Surface exposure dating · Climate change and permafrost · Cryospheric studies and observations · Geology and Paleoclimatology Research · Geology · Oceanography