Known for the numerous geothermal fields, Old Faithful Geyser is one of the most popular destinations in the park. Yellowstone lies at the eastern end of the Snake River Plain, which tracks the path of the North American Plate over the Yellowstone Hotspot. Here we are within the immense third caldera, created 640,000 years ago when some 240 cubic miles of material was catastrophically ejected.
All images copyright © 2016 F.W. Vollmer and may not be used without permission.