FIELD EXPERIMENTS ON THE TRANSPORT OF ROCK FRAGMENTS BY ANIMAL TRAMPLING ON SCREE SLOPES

Qualitative observations in an area with steep scree slopes in Turkey suggested that trampling by goats and sheep may contribute significant ly to the downslope movement of rock fragments in these environments. Therefore, a series of field experiments was set up to determine the r ate of rock fragment transport caused by trampling. The experimental r esults allowed the calculation of a unit displacement distance from ea ch trampling experiment, which may then be used to extrapolate the mea sured transport rates over longer time periods and larger areas. Altho ugh such extrapolations should be interpreted with great caution, the results demonstrate that trampling contributes significantly to rock f ragment transport in such environments, as calculated yearly displacem ent distances are equal to, or higher than, those reported in the lite rature for other geomorphic processes. The observed travel distance di stributions are not well described by a negative exponential distribut ion. Trampling causes a weak downslope sorting (the coarsest clasts mo ve farther) but has a significant effect on vertical sorting and is on e of the factors which can explain the layered structure of the scree slopes in the area. (C) 1998 Elsevier Science B.V. All rights reserved .