About two million years ago, Yellowstone’s enormous volcano, known as a super volcano, erupted violently and spread ash for thousands of miles, burying nearby ground in deep layers that later compressed or welded into the rock called Huckleberry Ridge Tuff. Yellowstone’s super volcano erupted two more times, and the most recent eruption left a gigantic caldera in the heart of Yellowstone about 30 miles wide and 45 miles long, first verified through satellite photography. These immense eruptions were many times larger than the catastrophic 1980 Mount St. Helens explosion in Washington. Yellowstone’s volcano is still alive today, and two dome-like areas rise and fall as magma moves beneath the park, offering clues about the future even though geologists cannot predict when it will erupt again.