An early carboniferous humus from South Wales preserved by marine hydromorphic entombment

Irregular, sub-metre scale occurrences of a highly unusual calcified peloidal (pelletal) limestone are described from a polygenetic paleosol from the sub-Arundian landsurface (Carboniferous, 343Ma) of South Wales. The pedogenic origin is supported by a suite of pedogenic features, and the textures in the peloidal carbonate mimic those of modern mull-like humus indicating the likelihood that the original soil biota was diverse. The occurrence of such material, normally with such a poor preservation potential, is explained by it being partially cemented and entombed by a brackish dolomite petrocalcic horizon, both formed as the landsurface was flooded by marine waters.