Physiography and soils in an area of miocene clays,merida, spain

Studies were undertaken to study physiography and soils in Merida area of Spain with the help of aerial photographs in order to make morphogenetic interpretation of the landscape for a clearer understanding of the distributional pattern of soils. Physiography of the area presents a picture of flat to convex low table lands in step like succession. These were termed as mesitas. The mesitas do not slope regularly from summit to the valley bottom, but show at least three to four changes in the gradient. The diflerent physiographic units and associated soils are discussed. The morphometry of the landscape, especially sequential occurrence of mesitas in step like succession, asymmetric valleys, presence of promontories on lower slopes transverse to the general gradient, idealised alterations of petrocalcic and calcic horizons from mesita summit to valley bottom indicated a major physiographic process of mass movement in the form of rotational slips. The distributional pattern of the soil is explainable on this basis. From the logical sequence of climatic changes and the geologic history of the area, it is believed that after the large scale sedimentation during Miocene period, followed by large scale climatic changes and accompanied by tectonic activities the process of mass moveme. it http://moveme.it could have started sometime in Pliocene.