A Geoscience Digital Image Library

TitlePumice boulder, Obsidian Dome, just north of Mammoth Lakes, California, USA
DescriptionThis is a large piece of pumice from Obsidian Dome, a 600 year old (very young!) rhyolite dome near Mammoth Lakes in eastern California. Obsidian Dome formed by rapid cooling of a viscous lava, and today consists of a jumbled mass of boulders and rocks of various sizes. Many, like this one, are made of pumice and/or volcanic glass. The overall composition of Obsidian Dome is the same as a rhyolite (fine grained extrusive igneous rock) and a granite (coarser grained intrusive igneous rock) but cooling was very rapid, and so much glass and pumice formed.
Geologic provinceInyo Volcanic Field
LocationUSA ▹ California ▹ Mono. Near Mammoth Lakes. Inyo National Forest.
PhotographerDexter Perkins. 2001-05-22.
Key wordsObsidian Dome, obsidian, pumice
Tech details564 KB. Outcrop. Canon Eos Rebel, 55 mm lens, Fuji Sensia 100.
GeoDIL number540