Shape and nature of small sedimentary quartz particles.
Quartz particles in sediments become flatter with decreasing size; a cleavage mechanism may operate below the critical size of about 100 microns. Flat particles would tend to form a more open packing than spherical particles, and this may contribute to the collapse of loess and similar soils and the sudden loss of strength observed in "sensitive" clay soils.
Krinsley
D H
DH
Smalley
I J
IJ