of the Snowmastodon Project on behalf of the Denver Museum of Nature & Science, told the New York Times, "The speed of this thing is so unlike normal science — from discovery to completion of one of the biggest digs ever in less than nine months." Scientists are not concerned now that the site is covered by water after completion of the reservoir expansion. Being underwater helps preserve the fossils and the reservoir can be drained if ever the need arises for additional excavations. Importance The Ziegler Reservoir fossil site is one of the few localities in North America from the Sangamonian Stage, and the only one at high elevation. This site preserves multiple alpine ecosystems stacked on top of each other within sediments of ancient alpine lake. Among the vertebrate fauna, this site represents highest known elevations of a number of species. Additionally, this site holds the record for the most mastodons preserved in a single location, including the largest mastodon ever found. The fossil flora offer unprecedented insights into plant biogeography of the Rocky Mountains during the last interglacial period. The site is also important for the exceptional preservation of fossil material. Fossil sedge and willow leaves were still green, conifer cones were still intact, and large driftwood logs were preserved. In addition, the mollusks and gastropods showed color, and beetle parts were still iridescent. Vertebrate fossil material was in excellent condition as well. The National Geographic Society, which donated a $55,000 grant to the project, featured the site in the National Geographic Magazine . The science television series Nova broadcast an episode about the site in February, 2012. Geologic Setting and Geochronology The Ziegler Reservoir occupies an unusual geologic setting on top of a ridge 2705 m above sea level. The lake basin was formed when a glacier flowing down Snowmass Creek Valley became thick enough to overtop the adjacent ridgeline. As the glacier retreated, a moraine impounded a 5 hectare alpine lake that was initially 10 meters deep. Over time, the lake filled in with wind-blown sediments until it became a marshland and ultimately an alpine meadow. After Doug Ziegler and his family purchased the land that now contains the Ziegler Reservoir, they commissioned the construction of a small earthen dam in 1961 to block the meadow drainage and form a shallow, private lake that persisted until the Snowmass Water and Sanitation District bought the water