Improved Schmidt-hammer exposure ages for active and relict pronival ramparts in southern Norway, and their palaeoenvironmental implications

Matthews, John A.; Wilson, Peter

doi:10.1016/j.geomorph.2015.06.002

Cited by 31 publications

(46 citation statements)

References 58 publications

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“…All locations along with representative surface gradients and directions are indicated in Figure . Boulder surfaces selected for SHD measurements were horizontal or near‐horizontal, and corners, cracks, lichen thalli and wet areas were avoided (Matthews and Wilson, ).…”

Section: Field Methods and Rationalementioning

confidence: 99%

“…Thus, the calibration equation was based on two control points of known age and each control point utilised all the data available from the control surfaces. This is justified by the generally consistent mean R‐values found from control surfaces of known age in the area (Matthews and Wilson, ). The equations used for age calibration include calculation of 95 per cent confidence intervals around predicted SHD ages; the calibration equation is a standard linear regression equation.…”

Section: Schmidt Hammer Exposure‐age Calibration and Age Estimationmentioning

confidence: 99%

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Relict Blockstreams at Insteheia, Valldalen-Tafjorden, Southern Norway: Their Nature and Schmidt Hammer Exposure Age

Wilson

Matthews

Mourne

2016

Permafrost and Periglac. Process.

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Two small relict blockstreams occur at Insteheia, a col at 910 m asl on the watershed between Valldalen and Tafjorden (Møre og Romsdal), southern Norway. Both blockstreams display morphological and sedimentological characteristics indicative of boulder accumulations that have moved downslope by solifluction, probably under a permafrost climatic regime. These comprise preferred orientation and dip patterns of boulders; inverse grading, with surface boulders overlying successively finer, well‐sorted cobble, pebble and fine‐grained (sand/silt dominated) sediment layers; imbrication, with the packing of small boulders behind larger boulders; and proximity to boulder‐strewn hillslopes whose constituent boulders (organised into lobes and terraces) feed downslope into the blockstreams. Schmidt hammer exposure ages indicate that the blockstreams were last active during the Younger Dryas Stadial‐Holocene transition. Blockstream development probably began at ~ 15 ka, following the Last Glacial Maximum, and lasted for ~ 5 ka. Since then any fine‐grained material within the near‐surface parts may have been progressively removed. The relatively rapid development of the blockstreams suggests that larger‐scale forms of considerably greater age in the southern hemisphere may also have formed rapidly and have been inactive for long periods. Copyright © 2016 John Wiley & Sons, Ltd.

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Section: Field Methods and Rationalementioning

confidence: 99%

Section: Schmidt Hammer Exposure‐age Calibration and Age Estimationmentioning

confidence: 99%

Relict Blockstreams at Insteheia, Valldalen-Tafjorden, Southern Norway: Their Nature and Schmidt Hammer Exposure Age

Wilson

Matthews

Mourne

2016

Permafrost and Periglac. Process.

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“…They also identified a layered structure at two drill core sites on the rock glacier. Relict rock glaciers are often used as an indicator of previous permafrost conditions for climate studies (e.g., Hughes et al 2013;Matthews and Wilson 2015), but their inner structure and hydraulic properties are largely unknown. Recently, Winkler et al (2016a) performed hydrogeological investigations at the relict Schöneben rock glacier located in the Austrian Eastern Alps (hereinafter referred to as SRG), describing its storage and flow components by using data of the spring hydrograph as well as natural and artificial tracers and geophysical surveys.…”

Section: Introductionmentioning

confidence: 99%

Investigating groundwater flow components in an Alpine relict rock glacier (Austria) using a numerical model

Pauritsch¹,

Wagner

Winkler

et al. 2016

Hydrogeol J

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Relict rock glaciers are complex hydrogeological systems that might act as relevant groundwater storages; therefore, the discharge behavior of these alpine landforms needs to be better understood. Hydrogeological and geophysical investigations at a relict rock glacier in the Niedere Tauern Range (Austria) reveal a slow and fast flow component that appear to be related to the heterogeneous structure of the aquifer. A numerical groundwater flow model was used to indicate the influence of important internal structures such as layering, preferential flow paths and aquifer-base topography. Discharge dynamics can be reproduced reasonably by both introducing layers of strongly different hydraulic conductivities or by a network of highly conductive channels within a low-conductivity zone. Moreover, the topography of the aquifer base influences the discharge dynamics, which can be observed particularly in simply structured aquifers. Hydraulic conductivity differences of three orders of magnitude are required to account for the observed discharge behavior: a highly conductive layer and/or channel network controlling the fast and flashy spring responses to recharge events, as opposed to less conductive sediment accumulations sustaining the long-term base flow. The results show that the hydraulic behavior of this relict rock glacier and likely that of others can be adequately represented by two aquifer components. However, the attempt to characterize the two components by inverse modeling results in ambiguity of internal structures when solely discharge data are available.

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“…), pronival ramparts (Matthews et al . ; Matthews and Wilson ), snow‐avalanche impact ramparts (Matthews et al . ), moraines (Matthews and Shakesby ; Evans et al .…”

Section: Introductionmentioning

confidence: 99%

Schmidt‐hammer exposure ages from periglacial patterned ground (sorted circles) in jotunheimen, norway, and their interpretative problems

Winkler

Matthews

Mourne

et al. 2016

Geografiska Annaler: Series A, Physical Geography

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Periglacial patterned ground (sorted circles and polygons) along an altitudinal profile at Juvflya in central Jotunheimen, southern Norway, is investigated using Schmidt‐hammer exposure‐age dating (SHD). The patterned ground surfaces exhibit R‐value distributions with platycurtic modes, broad plateaus, narrow tails, and a negative skew. Sample sites located between 1500 and 1925 m a.s.l. indicate a distinct altitudinal gradient of increasing mean R‐values towards higher altitudes interpreted as a chronological function. An established regional SHD calibration curve for Jotunheimen yielded mean boulder exposure ages in the range 6910 ± 510 to 8240 ± 495 years ago. These SHD ages are indicative of the timing of patterned ground formation, representing minimum ages for active boulder upfreezing and maximum ages for the stabilization of boulders in the encircling gutters. Despite uncertainties associated with the calibration curve and the age distribution of the boulders, the early‐Holocene age of the patterned ground surfaces, the apparent cessation of major activity during the Holocene Thermal Maximum (HTM) and continuing lack of late‐Holocene activity clarify existing understanding of the process dynamics and palaeoclimatic significance of large‐scale sorted patterned ground as an indicator of a permafrost environment. The interpretation of SHD ages from patterned ground surfaces remains challenging, however, owing to their diachronous nature, the potential for a complex history of formation, and the influence of local, non‐climatic factors.

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Improved Schmidt-hammer exposure ages for active and relict pronival ramparts in southern Norway, and their palaeoenvironmental implications

Cited by 31 publications

References 58 publications

Relict Blockstreams at Insteheia, Valldalen-Tafjorden, Southern Norway: Their Nature and Schmidt Hammer Exposure Age

Relict Blockstreams at Insteheia, Valldalen-Tafjorden, Southern Norway: Their Nature and Schmidt Hammer Exposure Age

Investigating groundwater flow components in an Alpine relict rock glacier (Austria) using a numerical model

Schmidt‐hammer exposure ages from periglacial patterned ground (sorted circles) in jotunheimen, norway, and their interpretative problems

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