NEWS RELEASE: Wyoming Geological Survey Publishes Pamphlet on the Geology in Sinks Canyon State Park

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Wyoming State Geological Survey

December 19, 2023


Media Contact:
Christina George
cell: (307) 703-0761


New WSGS Pamphlet Highlights Geology in Sinks Canyon State Park


A unique geologic wonder that attracts visitors to Sinks Canyon State Park is a river that seemingly disappears into a mountainside only to reappear down the canyon. While the “Sinks,” where the Middle Fork of the Popo Agie River vanishes, and the “Rise,” where the water resurfaces, are fascinating, the park holds more geology to discover. The Wyoming State Geological Survey (WSGS) details some of this geology in a new information pamphlet.

The Sinks Canyon State Park pamphlet is one in a series depicting geology in Wyoming’s state parks. Also available are pamphlets about the geology of Bear River, Boysen, Buffalo Bill, Curt Gowdy, Edness K. Wilkins, Glendo, Guernsey, Hot Springs, Keyhole, and Seminoe state parks.

“Wyoming’s state parks often have fascinating geologic stories to tell, and Sinks Canyon State Park is no exception,” says WSGS Director and State Geologist, Dr. Erin Campbell. “In addition to the scenic Middle Fork of the Popo Agie River and the dramatic Sinks, the canyon hosts rocks formed by ancient oceans and sand dunes, and the canyon floor is covered by deposits from past glacial events.”

Sinks Canyon State Park is on the eastern slope of the Wind River Range near the city of Lander. The range was formed during a large mountain-building event about 75 million years ago, which tilted the rocks at Sinks Canyon into their current orientation. River erosion carved out the canyon and exposed the rock units visible today.

“The geology in Sinks Canyon State Park is something that both young and old can enjoy,” says WSGS hydrogeologist, Kurt Hinaman. “The Sinks-and-Rise is a huge draw to the park, and the exact course the river takes underground remains a mystery.”

All WSGS state park information pamphlets are available as a free printable download. Pamphlets can also be picked up at the Survey’s office on the University of Wyoming campus in Laramie or ordered by mail (with a shipping fee) at the WSGS sales site.  


Sinks Canyon State Park

(Caption: The "Sinks," seen here, is where the Middle Fork of the Popo Agie River vanishes underground, entering a cavern in the Madison Limestone, only to reappear at the "Rise." WSGS photo)