ROCKSLIDE PROCESSES ON THE NORTH SLOPE OF POPOCATEPETL VOLCANO, MEXICO

This paper analyses the geomorphology of the north face of Popocatepet l Volcano (5450 m). The surface of the slope was covered earlier by th e northern Popocatepetl Glacier and gradually exposed during the curre nt century. The glacier formed at the time of the last great eruption of Popocatepetl in the seventeenth century, and reached its maximum ex tension at the end of the nineteenth century, at the peak of the Littl e Ice Age. A ramp formed at the snout of the glacier, composed primari ly of ash dating from the last eruption. The material was mixed with l arge boulders that have been bulldozed into place by the glacier snout . As the glacier retreated, deep gorges formed on the ramp and glacial hollows appeared at the base of the steep sides of the volanic cone. Today, large-scale rockslide processes occur on the north face. Layers of snow form a lubricating layer. The ash slides easily over the snow , covering it and later preventing it from melting and sublimation. Bl ocks fall from the present-day glacial snout and pile up on the snow. Later, they slide over the snow and infill the hollows and gorges.