Space view of YNP and the Surrounding Region.

Space view of Grand Teton and Yellowstone national parks from satellite images overlaid on digital elevation maps. The 8,000-foot-high Yellowstone caldera (marked III) was produced by a giant volcanic eruption 630,000 years ago. The caldera occupies a 45-by-30-mile-wide area of central Yellowstone. Partial boundaties of the calderas formed 2 and 1.3 million years ago are marked I, and II respectively. Computer image by E.V. Wingert. Used with permission from "Windows into the Earth, The Geologic Story of Yellowstone and Grand Teton National Parks", Robert B. Smith and Lee J. Siegel, Oxford University Press, 2000.