Textural properties of some source materials of clastic sediments

Abstract

The purpose of this study has been to measure and describe the size distribution, shape, roundness, and mineralogic composition of sediments recently weathered from granite and at or very near their source, and to discuss the significance of the values found for these parameters. For this purpose fourteen samples were collected from, and near, two granite knobs in the Llano area of central Texas. Three samples of gruss (arkosic sand) were collected from exfoliation pockets in Bear Mountain, near Fredericksburg, and three from Sandstone Mountain, near Llano (see location map, Figure 1). Eight additional samples were taken from a small intermittent stream draining from Sandstone Mountain to the Llano River, a distance of about one half mile.