The structure and sedimentology of relict talus, Knockan, Assynt, N.W. Scotland

Abstract

A 5 m high section through a talus accumulation reveals a thin layer of openwork debris overlying a predominantly clast‐supported diamicton. Sedimentological and petrological analyses show that the diamicton is composed of rockfall clasts and fines derived by granular disaggregation of the rockwall. Structural discontinuities and fabric analyses indicate periodic redistribution of sediment by debris flow, facilitated by the presence of fine sediment. The characteristics of the deposit thus favour models of talus development that envisage both rockfall accumulation and periodic downslope redistribution of debris, rather than steady‐state accumulation of clasts by discrete rockfall events.

Keywords:

• Debris flow
• Fabric analysis
• Granular disaggregation
• Sediment analysis
• Talus