In the autumn two years after the Yellowstone Supervolcano erupted, the US Geological Survey organized an expedition to examine the new caldera that had been formed in what had been Yellowstone National Park. The Survey managed to borrow a number of Humvees and crews from the Army and have them organize in Missoula, Montana. USGS geologist Larry Skrtel headed the expedition, with Doctors Kelly Ferguson and Daniel Olson who had worked with him previously, and Professor Geoff Rheinburg along as fellow geologists.