Photograph by S.R. Brantley on July 29, 1998

View of Obsidian Flow toward the north; Wilson Butte lava dome (mound in left center) and the lava flows and domes of the Mono Craters are visible behind Obsidian Flow. Wilson Butte was erupted between about 1,350 and 1,200 years ago. Obsidian flow is about 2 km in diameter and has a volume of 0.17 km³. The flow is 30-50 m thick along its margins and increases to more than 100 m near the conduit. At a depth of 400-500 m below the flow, the conduit is 33 m wide.