|Location:||Sinks Canyon, southwest of Lander.|
|Address:||Sinks Canyon State Park, 3079 Sinks Canyon Road, Lander, WY 82520, Tel: +1-307-332-3077|
|As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
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Sinks Canyon State Park shows a typical karst phenomenon: a vanishing stream. The Popo Agie River (pronounced Po-po' Zsha) vanishes into a sink or ponor, flows about 800m underground to reappear in a karst spring, the so called Rise.
The river crosses a patch of Big Horn Dolomite which is karstified. As soon as the water reaches the limestone it starts to form caves. When the soluble rock ends, it is forced to reappear and flow on the surface again. During times of high water in the river, the cave is not big enough to swallow all, so there is an overflow reanimating the old dry riverbed.