The Arthur Ross Terrace will be closed this morning, Tuesday, October 21, for a private cultural observance. You many observe smoke and/or fire coming from the Terrace at that time. The FDNY has been notified in advance, and all safety precautions are in place. The Terrace will reopen at 1 pm.
Obsidian is a volcanic glass, a comparatively rare and crystal-poor form of rhyolite, the most silica-rich lava. It forms when lava is quenches, or rapidly cooled. Obsidian is a major component of Glass Mountain.
Provided by Jeff Dinnel, Tionesta, California
Topic: Earth Science
Keywords: Lava, Medicine Lake (Cal.), Rhyolite, Volcanism, Volcanoes