Evidence of paleoprocesses in some poorly developed soils on consolidated material in the Sierra de Carrascoy (SE Spain)

Four representative profiles of poorly developed soils on consolidated mate rial were studied in the Sierra de Carrascoy (SE Spain). The soils, with A- A/R or A-C/R type profiles, have medium-low contents of organic carbon and nitrogen, and calcium carbonate occurs in only one of the profiles. The pH in aqueous suspension is slightly alkaline. The cation exchange capacity is medium-low, but varies slightly between profiles, and the electrical condu ctivity of the saturation extract is low. There are wide textural differenc es. The clay fractions contain illite, kaolinite, vermiculite, smectites, c hlorite, quartz and feldspars. The heavy fraction of the fine sand contains mainly opaque minerals and alterites, with some resistant minerals of meta morphic origin. The profiles are classified by F.A.O-I.S.R.I.C.-I.S.S.S. [W orld Reference Base for Soil Resources. World Soil Resources Reports 84, F. A.O,, Rome, 1998] as Calcaric, Eutric and Hyperskeletic Leptosols. Accordin g to Soil Survey Staff [Soil Taxonomy. A basic system of soil classificatio n for making and interpreting soil surveys, 2nd edn., United States Departm ent of Agriculture. Natural Resources Conservation Service. US Government P rinting Office, Washington, DC, 1999], they are all Lithic and Typic Xerort hents and Lithic Xeric and Xeric Torriorthents, The principal present-day p edogenetic processes in these soils are humification and clay formation. Ho wever, profile I has evolved from a fersiallitic soil with clay accumulatio n, although these features have almost disappeared because of erosion and m odem humification, pedoturbation and recalcification. Its relict features c onsist of the remains of a paleoargic horizon inherited from earlier climat ic conditions, which was later truncated and is now preserved only in more stable physiographic positions. (C) 2001 Elsevier Science B.V. All rights r eserved.