| Upper Mesa Falls | |
|---|---|
Upper Mesa Falls in June, 2008 |
|
| Location | Fremont County, Idaho |
| Type | Block |
| Elevation | 5,600 feet (1,707 m) |
| Total height | 114 feet (35 m)[1] |
| Watercourse | Henrys Fork (Snake River) |
Upper Mesa Falls is a waterfall on the Henrys Fork in the Caribou-Targhee National Forest. Upstream from Lower Mesa Falls, it is roughly 16 miles away from Ashton, Idaho.
Upper Mesa Falls is roughly 114 feet high and 200 feet wide.[2]
Mesa Falls Tuff, which is the rock over which Upper Mesa Falls cascades, was formed 1.3 million years ago. A cycle of rhyolitic volcanism from the Henrys Fork caldera deposited a thick layer of rock and ash across the area.[3] This layer compressed and hardened over time.
Between 200,000 and 600,000 years ago, the river eroded a wide canyon which was subsequently partly filled with basalt lava flows. The Henrys Fork of the Snake River then carved the channel through the basalt; which is the inner canyon seen today.