Ruby Mountain, Washington, USA
U.S. National Park Service photo (fair use policy)
Ruby Mountain lies in northernmost Washington state in Ross Lake National Recreation Area, a strip of land that crosses North Cascades National Park. It's not volcanic like most of the major Cascades peaks you might think of. Instead it consists of metamorphosed rocks of offshore origin, including mica schist and amphibolite, which represent former shale and basalt, respectively. These were bulldozed together and subjected to intense heat and pressure as a large chunk of crustal territory—the Chelan Mountains terrane—was stuck onto the North American continent like a sculptor thumbing a piece of clay onto a model statue. The western mountains from Washington to Alaska are a patchwork of "exotic terranes," rafted from elsewhere on top of crustal plates and plastered one after the other onto the Rockies.
More photos from the Cascade Range
