Conical Volcán Atitlán directly overlies the inferred margin of the Pleistocene Atitlán III caldera, whose northern rim lies across Lake Atitlán. Atitlán volcano forms a paired volcano with Tolimán to its north (seen just to the right of Atitlán's summit). The historically active Atitlán is younger than Tolimán, although their earlier activity overlapped. In contrast to Tolimán, Atitlán displays a thick pyroclastic cover, reflecting its predominantly explosive eruptions that have been recorded since the 15th century. Photo by Bill Rose, 1980 (Michigan Technological University).