Rapid age assessment of glacial landforms in the Pyrenees using Schmidt hammer exposure dating (SHED)
Résumé
Schmidt hammer (SH) sampling of 54 10 Be-dated granite surfaces from the Pyrenees reveals a clear relationship between
exposure and weathering through time (n=52, R 2 =0.96, P<0.01) and permits the use of the SH as a numerical dating
tool. To test this10 Be-SH calibration curve, 100 surfaces were sampled from five ice-front positions in the Têt catchment,
eastern Pyrenees, with results verified against independent 10 Be and 14 C ages. Gaussian modelling differentiates Holocene
(9.4±0.6ka), Younger Dryas (12.6±0.9ka), Oldest Dryas (16.1±0.5ka), last glacial maximum (LGM; 24.8±0.9ka)
and Würmian maximum ice extent stages (MIE; 40.9±1.1ka). These data confirm comparable glacier lengths during the
LGM and MIE (~300m difference), in contrast to evidence from the western Pyrenees (≥15km), reflecting the relative
influence of Atlantic and Mediterranean climates. Moreover, Pyrenean glaciers advanced significantly during the LGM,
with a local maximum at ~25ka, driven by growth of the Laurentide Ice Sheet, southward advection of the polar front,
and a solar radiation minimum in the Northern Hemisphere. This calibration curve is available online (http://shed.earth) to
enable wider application of this method throughout the Pyrenees.