ILLUVIAL BAND FORMATION IN A LABORATORY COLUMN OF SAND

Experiments are described in which thin clay bands were formed by illuvial processes in a laboratory column of fine sand containing < 1% clay. It is hypothesized that band formation resulted from dispersion of clay in the sand and its subsequent deposition, which was triggered by layers of small pores within the sand column, and/or by exceeding the maximum possible suspension concentration. The results permit a number of comments to be made about the occurrence and formation of illuvial clay bands, as well as precautions that should be taken when carrying out water flow experiments in sandy soils.