On the domed structure and anisotropy of the B horizon of a solodized solonetz

Abstract

The domed columnar structure of the B horizon of solodized solonetz soils has been considered to be caused by the swelling and shrinking properties of sodium clays in the B horizon under seasonally wet and dry conditions. Such an observation, however, gives no explanation of how such soil morphology developed. With the intention of obtaining some information of the process by which the domed structure of the columns might be generated, some physical, chemical, and mineralogical characteristics of two domed columns were examined. Swelling, water retention, clay content, clay mineral species, and potassium content were some of the properties that varied systematically with position, both vertically and, more importantly, radially from the axes of the columns. That the domed columns are anisotropic was shown by these analyses. The domed structure of the columns appears to be generated by swelling strains caused partly by sand blocking the vertical cracks thereby causing horizontal confinement and partly by an increased ability to swell, even when unconfined, of the clay nearer to the axes of the columns. This increased swelling is associated with a greater degree of interstratification of the clay minerals nearer to the axes of the columns.