THE GEOMORPHOLOGICAL EVOLUTION OF THE PARICUTIN CONE AND LAVA FLOWS, MEXICO, 1943-1990

Erosion and sedimentation processes in the Paricutin cone and adjacent lava fields have been evaluated 47 years after the eruption through f ield study of the morphological characteristics of the area. Previous studies indicate an initial stage of accelerated erosion, decreasing q uickly after the stripping of the ash layers and cessation of the volc anic activities. In the cone and crater area, revegetation is the main process, after the first stage of stripping of fine ash. The lava fie lds are the least affected areas by erosional processes, with vegetati on development in minor depressions, crevices and along the edges of t he lava flows. The ''llanos'' or lava dammed plains, are the most acti ve physiographic units, with continuous deposition of sediments. They are completely covered by vegetation or under agricultural use. Incisi on of channels along the lava field edge promotes the integration of t he drainage system, but still most of the affected area drains into th e lava field. Present erosion rates are higher than normal rates, and a complete rehabilitation of the pyroclastic area may extend over deca des. Filling of sediments and revegetation of the lava fields will dev elop in a longer period of several millennia.