Yellowstone 1953 | Yellowstone Canyon The Yellowstone River created today’s Yellowstone Canyon. It begins on the slopes of Younts Peak and travels more than 600 miles to North Dakota where it empties into the Missouri River. It’s the longest undammed river in the continental United States. The specific geologic history of the canyon are not clearly understood. The canyon today is 800 to 1,200 feet deep and 1,500 to 4,000 feet wide and was made by erosional forces not glaciation. The canyon is a classic V-shaped valley made by river-type erosion and is still eroding today. Still, when viewing it from Inspiration Point, it does not look like it has changed much since 1953.
After the caldera eruption some 600,000 years ago, the canyon area was faulted by the doming action of the caldera before the eruption. The present canyon as well as previous canyons was probably the result of this faulting, which accelerated the rate of erosion. Still, the present canyon area was also covered by glaciers that followed the volcanic activity. Glacial deposits may have filled the canyon. The present canyon is less then than 10,000 to 14,000 years old.
