Upper Mesa Falls
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Upper Mesa Falls is a waterfall on the Henrys Fork in the Caribou-Targhee National Forest. It is roughly 16 miles away from Ashton, Idaho.
Upper Mesa Falls is roughly 114 feet high and 300 feet wide. [1]
[edit] Formation
The Mesa Falls Tuff, which is the rock over which Upper Mesa Falls cascades, was formed 1.3 million years ago. A volcanic eruption deposited a thick layer of ash. 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.
