Abstract. A new luminescence erosion meter has huge potential for inferring erosion
rates on sub-millennial scales for both steady and transient states of
erosion, which is not currently possible with any existing techniques
capable of measuring erosion. This study applies new rock luminescence
techniques to a well-constrained scenario provided by the Beinn Alligin rock
avalanche, NW Scotland. Boulders in this deposit are lithologically
consistent and have known cosmogenic nuclide ages and independently derived
Holocene erosion rates. We find that luminescence-derived exposure ages for
the Beinn Alligin rock avalanche were an order of magnitude younger than
existing cosmogenic nuclide exposure ages, suggestive of high erosion rates
(as supported by field evidence of quartz grain protrusions on the rock
surfaces). Erosion rates determined by luminescence were consistent with
independently derived rates measured from boulder edge roundness. Inversion
modelling indicates a transient state of erosion reflecting the stochastic
nature of erosional processes over the last ∼4.5 kyr in the
wet, temperate climate of NW Scotland. Erosion was likely modulated by known fluctuations in moisture availability and to a lesser extent temperature, which controlled the extent of chemical weathering of these highly lithified rocks prior to erosion. The use of a multi-elevated temperature, post-infra-red, infra-red stimulated luminescence (MET-pIRIR) protocol (50, 150 and 225 ∘C) was advantageous as it identified samples with complexities that would not have been observed using only the standard infra-red stimulated luminescence (IRSL) signal measured at 50 ∘C, such as that introduced by
within-sample variability (e.g. surficial coatings). This study demonstrates that the luminescence erosion meter can infer accurate erosion rates on sub-millennial scales and identify transient states of erosion (i.e. stochastic processes) in agreement with independently derived erosion rates for the same deposit.