Holocene reworking of drift-mantled hillslopes in Glen Docherty, NorthwestHighlands, Scotland

Sections exposed within a colluvial debris cone in Glen Docherty, Scotland, reveal in-situ palaeosols intercalated with debrisflow diamictons and hori zons of slopewash deposits. Radiocarbon dating of the palaeosols suggests t hat drift reworking at this site involved brief, intermittent episodes of d ebrisflow and slopewash activity since c. 6.5 cal. ka BP. At least four suc h phases can be recognized: c. 6.5-6.2, 5.6-5.3, 4.9-4.6 cal. ka BP and aft er c. 450 cal. BP. The palaeosols examined show no evidence of local burnin g of vegetation. A calibrated radiocarbon age for the onset of the most rec ent phase of reworking may be interpreted as reflecting woodland clearance and/or the influence of extreme rainfall events during the 'Little Ice Age' period of regional climatic deterioration. The combined chronostratigraphi c and palaeoecological evidence points to discrete, local rainstorms that a re seemingly unrelated to long-term climatic change as the most likely caus e of enhanced slope reworking, at least prior to c. 450 cal. BP. If this in terpretation is valid, it implies that the formation of Holocene debris con es elsewhere in upland Britain may have been due primarily to a small numbe r of localized, extreme rainstorm events. Consequently, caution is necessar y in using debrisflow chronostratigraphy alone as a means of reconstructing long-term climate patterns.