by The American Geosciences Institute Tuesday, June 26, 2018
At times of low runoff (as in this picture), the river drains through a solution cavity in Paleozoic limestone. During times of high runoff, however, water fills the dry channel above the cavity, spilling over the cliff and creating a 30-meter-high waterfall.
The waterfall, located about 60 kilometers north of a colorfully named national park, was named after a nearby natural feature that collapsed in July 1988.
This river is the better known of two in the state with the same “rocky” name, and is a popular destination for hiking, camping and fishing.
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Answer: At times of low runoff, Natural Bridge Falls in Montana, which lies about 60 kilometers north of Yellowstone National Park, drains through a solution cavity in Paleozoic limestone. At times of high runoff, the Boulder River flows over a cliff producing a 30-meter-high waterfall. Photo by Jim Sukup.
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