Geology

In Yellowstone, geology is not the study of dead rocks. It's a dynamic process that's constantly reshaping the landscape. In Yellowstone's geothermal areas, rainwater seeps through the ground until it hits magma deep within the Earth's crust, where it is heated and propelled back through cracks in the crust, emerging in the form of the park's famous geysers, hot springs, and other famous features. Earthquakes frequently rumble and move the ground, and volcanic eruptions have altered and reshaped these lands time and again over the millennia. Yellowstone is the largest volcanic system in North America, and volcanic action, or vulcanism, has shaped the landscape you see all around you. The Wabash Range of mountains is comprised of ancient volcanic mudflows accumulating over 10 million years. Elephant Back Mountain was shaped by a lava flow; Canyon Village sits on another bed of rhyolite, the form of granite arising from cooled lava. You can see the many types of volcanic lava that shaped the landscape by visiting the Grand Canyon of the Yellowstone River, where erosion has exposed the various strata of rock.