Surficial geologic history of the Canyon Village Quadrangle, Yellowstone National Park, Wyoming, for use with map I-652

Richmond, Gerald

The Canyon Village quadrangle lies in central Yellowstone National Park. It includes the northern part of Yellowstone Lake and the spectacular sector of the Grand Canyon of the Yellowstone seen by most visitors. The oldest Quaternary event recognized in the quadrangle occurred about 600,000 years ago when a large caldera, covering most of the quadrangle, collapsed after eruption of vast quantities of tuff. Events prior to the Sacagawea Ridge Glaciation include primarily a lake in the caldera and the eruption from beneath the lake of a large rhyolite flow. Possible glaciolacustrine deposits but no till of the Sacagawea Ridge Glaciation were found in the quadrangle. However, Sacagawea Ridge Till derived from sources in Yellowstone National Park occurs just outside the park. During the Sacagawea Ridge-Bull Lake interglaciation, further eruptions of rhyolite flows and tuffs in the caldera constructed the present Central Plateau and thereby separated the eastern part of the lake from a former outlet to the west. As a result, the eastern lake rose, and its overflow to the north initiated erosion of a paleocanyon along the course of the present Grand Canyon of the Yellowstone. The subsequent history of the canyon and of the caldera lake consisted largely of a succession of major advances and recessions of Bull Lake and Pinedale glaciers, and eruptions of rhyolite flows during both glacial and interglacial or interstadial times. canyon, in this quadrangle, was partly filled with lake sediments deposited upstream from ice dams during both stades of the Bull Lake Glaciation. A major withdrawal of the ice occurred between the early and late stades of the Bull Lake Glaciation and during the Bull Lake-Pinedale interglaciation. A major shrinkage of the ice also took place between the early and middle stades of the Pinedale Glaciation; final wasting was very rapid and occurred between about 13,600 and 12,000 years ago.