Pebble Orientation in Fluvial Sediments

Abstract

ABSTRACT Measurements of long axis orientations of elongate pebbles in dry channels on river braid bars show that the highest degree of preferred orientation is obtained from populations of large pebbles isolated on sand beds. Smaller size or increased concentration of the pebbles reduces the degree of preferred orientation. With flat pebbles, a stronger upstream imbrication mode is developed when the pebbles are in contact.