CHARACTERISTICS, GENESIS, AND CLASSIFICATION OF PENNSYLVANIA MINESOILS

Abstract

This paper reports on 24 nontopsoiled, noncultivated minesoils described and sampled in Pennsylvania. The minesoils varied in age from 1 to 29 years. They all have high rock fragment contents (40 to 60% in the surface and >70% in the subsoil). The lower content of rock fragments in the surface plus a higher content of small fragments in this zone compared with the subsoil indicates that some weathering has taken place. Particle size data indicate no significant eluviation, although some clay films were observed in subsurface horizons. The morphology indicates weak profile development, with the majority (21 of 24) of the minesoils having sola of 50 cm or less. Morphological data also indicate that the solum is developing at a rate of about 1.6 cm per year. Soluble salts, primarily gypsum, were found in many of the soils, and their concentration increased with depth, exceeding toxic levels in some soils. Organic carbon data showed no trends that could be evaluated. The iron oxide content of the minesoils was relatively high and indicates rapid oxidation and some inherited free iron oxide. The pH of most minesoils was low, and the majority of them had at least one horizon with a pH of < 4.0. Thus the majority of these weakly developed soils have in the past and are currently undergoing a significant phase of acid-sulfate weathering. Although they were undergoing acid-sulfate weathering, we noted no effect of the weathering on the clay mineralogy. The majority (79%) of the minesoils would be classified as Entisols, and the remaining 21% have weakly expressed cambic horizons and should be classified as Inceptisols.