Yellowstone Park: Supervolcano

Yellowstone park sits on top of one of the biggest volcanoes on earth - in fact it is a supervolcano that has erupted several times with massive force over the course of the last two million years. Geysers like Old Faithful are a tell-tale sign that volcanic activity is going on just beneath the surface. The Independent published an article on supervolcanoes earlier this year.
Click on the following links from the National Park to find out more about the Yellowstone Volcano.
The ingredients of a geyser.
What is driving the geyser.
Where is the Volcano?
Old Faithful Webcam.