Mechanical replacement processes in mobile soft calcic horizons; their role in soil and landscape genesis in an area near Mérida, Spain [antikvár]

Abstract Elbersen, G.W.W. (1982). Mechanical replacement processes in mobile soft calcic horizons; their role in soil and landscape genesis in an area near Merida, Spain. Agric. Res. Rep. (Versl. landbouwk. Onderz.) 919, ISBN 90-220-0810-X, (xii) + 208 p., 47 figs, 16 tables, 204 refs. Eng., Du., Sp. and Fr. summaries. Also: Doctoral thesis, Wageningen. A mechanical replacement process is described to explain the way in which soft calcic horizons become 'mobile' and actively penetrate the soil. This model implies that the horizons are pedogenetic features which may be very old since they can escape exposure in a landscape subject to erosion. The lime they contain can be derived from the weathering strata through which they have passed in the course of time. The process is initiated by subterranean gilgai formation which introduces soil material into the lower part of the calcic horizon which subsequently moves this material upward and expels it from the top. The transport process was re-created in the laboratory and monitored by stereo radiography. Its driving force is derived from air enclosure which occurs upon wetting of crystalline powdery lime. Field data from the study area have yielded evidence of the replacement process and indicate the main controlling factors. Rates of downward movement of the calcic horizons have been calculated to be of the same order of magnitude as representative erosion rates for the area. Implications of the process for soil science, agriculture, geomorphology and archeology are briefly treated. Free descriptors: calcic horizons, caliche, calcrete, soft powdery lime, gilgai, air enclosure, dating carbonates, erosion rates, carbonate leaching, petrocalcic horizons, genesis of calcic horizons.