Geology Reference
In-Depth Information
FIGURE 4.5 Simplified geologic map of Yellowstone National Park. The rock units are combined into three major categories. Pre-
caldera rocks are those that were deposited before the major eruption 640,000 years ago, and include sedimentary, igneous, and
metamorphic rock units. The Lava Creek Tuff is the pyroclastic flow unit that was deposited when the caldera erupted 640,000 years
ago. Postcaldera rhyolite flows now fill and extend beyond the hole made by the caldera collapse. Star symbols indicate volcanic vent
areas.
(Modified from Christiansen, 2001, Kciffer, 1971, and Lowenstern and others, 2005)
Search WWH ::




Custom Search