Sunset Crater, the most recent cinder cone in the San Francisco Volcanic Field, is estimated to have erupted between A.D. 1085 and 1090. In areas where the resulting lava flows were greater than 30cm thick, people may have been forced to migrate, leaving behind long-established homesteads and agricultural fields. On the positive side, lower elevation areas with cinder fall in the range of 3-10 cm would have become more suitable for farming, due to the beneficial effects of the cinder mulch. We talk with Volcanologist Michael Ort, who, together with a team of scientists, has unraveled the timing of these events and the implications of volcanic activity for humans at the time.