Spurred on by these reports, Hayden organized his expedition with the support of a $40,000 appropriation from Congress. On June 1, 1871, a team of 34 men and seven wagons, set out from Ogden, Utah. Among the group were geologist and managing director James Stevenson, mineralogist A. C. Peale, topographer Antoine Schoenborn, artists Henry W. Elliott and Thomas Moran, and photographer William H. Jackson. The latter two proved to be invaluable members of the expedition for their work served as dramatic and effective publicity in favor of establishing the park. Moran’s famous landscapes were afterwards hung in the halls of Congress and Jackson’s equally famous photographs portraying the primeval grandeur of the Yellowstone were widely distributed. [Illustration: William Henry Jackson, self-portrait. Jackson made this exposure while exploring the Tetons in 1872.] [Illustration: The Hayden Survey, led by Lieutenant Gustavus C. Doane, about to enter the Yellowstone area. The two-wheeled vehicle, in the center foreground, is an odometer, a horse-drawn device used to measure distances travelled in the wilds.] After several weeks travel, the Hayden expedition reached Boetler’s Ranch in the Yellowstone River Valley. There they were joined by the Barlow-Heap military party of engineer-explorers who also planned a reconnaissance of the Upper Yellowstone. This latter group intermittently explored with the Hayden expedition during the next several weeks. The results of the Barlow-Heap explorations were published as a modest Senate Document which proved to be of material help in establishing the Yellowstone National Park. The joint Hayden/Barlow-Heap expeditions departed from Boetler’s on July 20, 1871. The journey through the wilderness was by no means an easy one. The wagons had to be abandoned and the gear packed on mules. Progress was slow, and the difficulty of moving through the dense forest was compounded by the great number of trees felled by fires that periodically swept the region. The Yellowstone Basin however, proved to be an ideal open-air laboratory for the geologist, and perhaps one of the best places on earth for studying active volcanic processes because of the wide variety of geologic features. Each of the scientists accompanying the expedition found unique opportunities for observation and study.