Popo Agie Watershed: Geology

Cirque of the Towers

The three main tributaries of the Popo Agie River originate in the igneous and metamorphic rock types in the Wind River Mountain Range. Precambrian granite, the oldest rock formation on earth, is found in abundance at the high elevations and forms the peaks and cirques the Wind River mountain range is famous for. Much of the Popo Agie Watershed was eroded and partially covered with sedimentary deposits from receding seas to create many different shale, claystone and sandstone rock beds at lower elevations. These formations have been exposed over time by natural processes of stream and wind erosion, which created varied and vibrantly colored topography.

Red Canyon
Red Canyon is an excellent example of the colorful sedimentary formations. The formations include the pink and orange Nugget sandstone and the vibrant red Chugwater formation which form the spectacular cliffs and valleys of this remarkable canyon.

Glaciers and Snow Fields
The mountainous areas of the Popo Agie Watershed were glaciated at least three times to produce the present landscape. Although permanent snow fields are still present, remnants of past glaciations are easily identifiable in the extensive boulder fields on the North and Middle Fork drainages.

Popo Agie Falls
The Middle Fork of the Popo Agie River proudly claims the stunning Popo Agie Falls, which tumble 60 feet down the canyon wall. The Falls are a popular destination in the watershed, and serve as a magnificent introduction to the Shoshone National Forest and Wind River Mountain Range.

The Popo Agie River disappears into a limestone cavern in Sinks Canyon

The Sinks and Rise
The geology of the Popo Agie Watershed supports other fascinating natural features. “The Sinks” is a remarkable site located in Sinks Canyon State Park where the Middle Fork of the Popo Agie River disappears into a large limestone cavern. The river then runs underground for an estimated 1/4 mile, where it reappears in a large, calm, trout-filled pool known as “The Rise”. In order to study this phenomenon, geologists used dye tests to determine the distance the water travels after it enters the giant cavern. Although the actual subterranean path remains a mystery, the dye took over two hours to reappear at The Rise!

Oil Production in the Popo Agie Watershed
The Popo Agie Watershed contains several oil fields, the most notable being Dallas Dome. Dallas Dome claims the first commercial oil well drilled in Wyoming in 1884, which is still in production today. Dallas Dome also claims a unique natural “tar spring” which was documented by pioneers in the area as early as 1827. Another historic oil field, Derby Dome, is nearby and also remains productive.