Development of the Chemical Composition of Sand

The chemical composition of the single types of source rocks and the sand fraction 63 — 500 μm of the soils, of the effective composition of the source rocks and soils, of the river-mouth sediments and of the longshore bar is compared. Gain and loss and constant-AI₂O₃ calculations reveal that the composition of the river-mouth sands comes closer to the source rocks than to the soils. Attrition during fluvial transport is the most important source of sand at this active plate margin, chemical weathering and soil formation being less effective.The chemical composition of the average Calabrian river-mouth sand fits almost perfectly that of active-margin sandstones; single rivers, however, deviate greatly from this mean and it may be hazardous to draw conclusions from only one or even a limited number of rivers.