Micropitting of some clay materials adjacent structural pores

Micrometre-sized pits (micropits) were observed both in clay coatings within the upper B horizon of a Red Podzolic soil (Udic Haplustalf), and in the clay matrix adjacent structural pores within a calcitic buried soil. SEM-EDXRA and SEM-low temperature ashing were used to characterise these features and to determine their probable pedogenesis. The micropits in the Red Podzolic B horizon were around 2 μm in size, had either a hemi-ovoidal or a hemi-spheroidal morphology, and were formed by the lysis of microbial cells which had been partially buried during clay deposition on these surfaces. The micropits in the calcitic layer were up to 3 μm in size, were irregularly shaped, and were formed by the dissolution of calcite crystals embedded in the clay matrix.