Morphology and genesis of silt and clay coatings in the vesicular layer of a desert loam soil

Abstract

The microscopic and submicroscopic characteristics of the vesicles in a Desert Loam (Haplic Durargid) soil were examined. The surface roughness of the vesicles depended on the texture of the material in which they formed. Plate-like silt and coarse clay particles on the vesicle surface were strongly oriented having a pavement-like appearance. Silt and clay coatings lined many of the vesicles and interconnected channels. Many vesicles occurred in clusters and contained layered coatings of different thickness: clay coatings up to 200 µm, silt coatings up to 300µm, and composite coatings up to 1 mm. Some radially cracked clay coatings also contained silt depositions within the cracks. The probable genesis of the clay coatings involves the translocation of clay particles from an external source, through the raindrop-disturbed surface layer, and around entrapped air bubbles within vesicles. The morphology of the coating indicates that the vesicles in this soil layer have considerable durability.