Pyroclastic flow deposits are the thick, massive beds. The pyroclastic surge deposits are the duned and cross bedded deposits. Field study with Professor Hans-Ulrich Schmincke and students in 1980. Maar or hydrovolcanic deposits Cerro Colorado volcano , Pinacate Volcanic Field, northern Mexico is a maar volcano with a broad crater and low rims formed by hydrovolcanic processes. Prevailing winds blew toward the southwest at the time of eruption to form the high point of the rim.
Rim beds inside maar crater , Ukinrek volcano, Alaska.
Arrow points to Dr. Michael Ort, Northern Arizona University, rappeling down crater wall to investigate origin of beds. Dr. Wendell Duffield of the U.S. Geological Survey is on the crater rim holding the rope. Photograph by Maurice and Katia Krafft. Ash fall on hut 3 km from rim of Pinatubo volcano, Philippines, after the major 1991 eruption. Photograph by R. P. Hobblitt, U.S. Geological Survey.