These are mines in the hills above Bannack, Montana (USA), a town that was formed in the 1860’s when gold was discovered in Grasshopper Creek. This mountain in the Pioneer range is part of the Idaho Batholith, a huge granite formation that was pushed into Mountana when the plate that Idaho is on collided with the North American plate. Granite is a good source for gold, since that metal is associated with quartz, a required constituent of granite.
I’m entering this in the Large Granite Mountain challenge in the Volcanoes, Earth’s Geology & Atmosphere group.
Photo taken September 5, 2011 with a Kodak EasyShare Z712 IS camera.