Global Volcanism Program | Image GVP-07433
Stream erosion exposes an outcrop of the Upper Toluca Pumice, which originated during the last large Plinian eruption of Nevado de Toluca volcano some 10,500 years ago. This eruption produced a sequence of pyroclastic flow, pyroclastic surge, and ashfall deposits. Note the person at the top of the outcrop for scale. The Upper Toluca Pumice was distributed primarily to the NE and is found over much of the Valley of México.
Photo by José Macías, 1995 (Universidad Nacional Autónoma de México).