This high-country plateau (approximately 7-miles in length and 7-miles wide) is a prime location for bison, grizzly bear, elk, pronghorn, wolves, and lots of waterfowl. It is also the location of the largest rut of free-roaming bison in the world. The rut seems to peak during the month of August. Sounds of deep guttural bellows can be heard across the valley as bison congregate for the annual rut, and the bulls square off in intense and powerful battles to compete for mating privileges.
The valley is named after Ferdinand V. Hayden, a geologist, and leader of the 1871 Geological Survey who played an important role in efforts to convince the U.S. Congress to pass legislation in the creation of the world’s first national park – Yellowstone.
Hayden Valley was once covered with an ice cap and later filled with water as a result of a glacial blockage of the flow of the Yellowstone River approximately 13,000 years ago. With the breakup of the glacier and the restoration of river flow, the valley drained leaving a deposition of glacial till of several different grain sizes including clay. This combination of sediments created a relatively impermeable layer making it difficult for water to reach far into the ground. As a result, the area is somewhat marshy with abundant grasses, but trees that require deeper penetration of water into the ground are sparse.