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exposure dating (SHED): Calibration procedures, new exposure age data and an online calculator. Quaternary Geochronology, 44, 55-62. https://doi.Abstract 5 Recent research has established Schmidt Hammer exposure dating (SHED) as an effective method 6 for dating glacial landforms in the UK. This paper presents new data and discussion to clarify and to 7 evaluate calibration procedures. These make a distinction between Schmidt Hammer drift following 8 use (instrument calibration), and variation between both individual Schmidt Hammers and between 9 user strategies when utilising age-calibration curves (age calibration). We show that while test anvil 10 methods are useful for verifying that Schmidt Hammers maintain their standard R-values, they are 11 inappropriate for instrument calibration except for the hardest natural rock surfaces (R-values: ≥ 12 70). A range of surfaces were tested using 3 N-Type Schmidt Hammers, which showed that existing 13 anvil calibration procedures led to consistent overestimation of R-values by up to 17.9%. In contrast, 14 new calibration procedures, which are based on the use of a calibration point which lies within the 15 range of R-values measured in the field [Dortch et al. 2016, Quat. Geochron., 35, 67-68], limit 16 variance to maximum of 4.4% for surfaces typically tested by Quaternary researchers (R-values: 25 -17 60). Moreover, these new calibration procedures are more appropriate for age calibration as they 18 incorporate operator variance through choice of sampling location. New calibration procedures are 19 used to compile an updated age-calibration curve based upon 54 granite surfaces (R 2 = 0.94, p < 20 0.01) from across Scotland, NW England and Ireland. The inclusion of a further 29 terrestrial 21 cosmogenic nuclide (TCN) exposure ages extends the calibration period to 0.8 -23.8 ka, covering 22 the entire post-Last Glacial Maximum (LGM) history of the British-Irish Ice Sheet. To facilitate 23 comparison between studies, an online calculator is made available at http://shed.earth for Schmidt 24Hammer instrument and age calibration and SHED exposure age calculation. The SHED-Earth 25 calculator provides a rapid and accessible means of exposure age calculation to encourage wider and 26 more consistent application of SHED throughout the British Isles. 27 28

October): Small rock-slope failures conditioned by Holocene permafrost degradation: a new approach and conceptual model based on Schmidt-hammer exposure-age dating, Jotunheimen, southern Norway.Rock-slope failures (RSFs) constitute significant natural hazards, but the geophysical processes that control their timing are poorly understood. However, robust chronologies can provide valuable information on the environmental controls on RSFoccurrence: information that can inform models of RSF activity in response to climatic forcing. This study uses Schmidt-hammer exposure-age dating (SHD) of boulder deposits to construct a detailed regional Holocene chronology of the frequency and magnitude of small rock-slope failures (SRSFs) in Jotunheimen, Norway. By focusing on the depositional fans of SRSFs (≤10 3 m 3 ), rather than on the corresponding features of massive RSFs (~10 8 m 3 ), 92 singleevent RSFs are targeted for chronology building. A weighted SHD age-frequency distribution and probability density function analysis indicated four centennial-to millennial-scale periods of enhanced SRSF frequency, with a dominant mode at~4.5 ka. Using change detection and discreet Meyer wavelet analysis, in combination with existing permafrost depth models, we propose that enhanced SRSFactivity was primarily controlled by permafrost degradation. Long-term relative change in permafrost depth provides a compelling explanation for the high-magnitude departures from the SRSF background rate and accounts for: (i) the timing of peak SRSF frequency; (ii) the significant lag (~2.2 ka) between the Holocene Thermal Maximum and the SRSF frequency peak; and (iii) the marked decline in frequency in the late-Holocene. This interpretationis supported bygeomorphological evidence, as the spatialdistributionofSRSFs isstrongly correlatedwith the aspect-dependent lower altitudinal limit ofmountain permafrost in clifffaces. Resultsare indicative of a causal relationship between episodes of relatively warm climate, permafrost degradation and the transition to a seasonal-freezing climatic regime. This study highlights permafrost degradation as a conditioning factor for cliff collapse, and hence the importance of paraperiglacial processes; a result with implications for slope instability in glacial and periglacial environments under global warming scenarios.

Link to publication record in Manchester Research Explorer Citation for published version (APA):Tomkins, M., Dortch, J., Hughes, P., Huck, J., Stimson, A., Delmas, M., Calvet, M., & Pallas, R. (2018). Rapid age assessment of glacial landforms in the Pyrenees using Schmidt Hammer exposure dating (SHED). Quaternary Research, 90(1), 26-37. https://doi. ABSTRACT 22Schmidt Hammer (SH) sampling of 54 10 Be dated granite surfaces from the Pyrenees reveals a clear 23 relationship between exposure and weathering through time (n = 52, R 2 = 0.96, p < 0.01) and 24 permits the use of the SH as a numerical dating tool. To test this 10

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