ABSTRACT

The role of rock type in controlling downstream variation in clast parameters in non-jokulhlaup-affected, Oraefi sandar in Iceland was evaluated. Clast changes in the Svinafellsa are simple, but the effects of tributary sources complicate the clast parameter-distance relationships in the Morsardalur-Kjos system. The behavior of individual rock types must be studied to understand the changes. Both selective sorting and abrasion are taking place, and the relative importance of these processes is evaluated. The volcanic rocks are rounding relatively rapidly, with variation among individual rock types, but there are no significant changes in sphericity and clast form with distance. The compressive strength of the volcanic suite is variable, and significant weathering changes must be takin place during transport from rock face to distal sandur. The influence of such weathering changes on changes in clast parameters needs further research.