Geology & Natural History

Seminoe and Kortes dams, both located in a remote stretch of northern Carbon County, Wyo., were constructed in the 1930s and 1940s primarily for the production of hydropower. While power plants at both dams still generate electricity, the area is frequented by tourists, especially fishermen who travel to the renowned Miracle Mile, just downstream from Kortes Dam, to catch trout.

Boysen Dam, named for local businessman Asmus Boysen, was constructed on the Wind River in the 1940s to control flooding and to provide irrigation water for agricultural purposes. The dam was completed in early 1953 and its power plant continues to generate electricity today. Boysen Reservoir provides recreational opportunities as well.

The abundant vertebrate fossils of the Green River formation in western Wyoming have been known to science since the 1860s. Most are fish, buried in lime-rich mud at the bottom of freshwater lakes about 50 million years ago. Fossil Butte National Monument, west of Kemmerer, Wyo. was created by Congress in 1973 to protect a site extremely rich in these fossils.

Devils Tower, a basalt column rising 1,267 feet above the nearby Belle Fourche River, was the nation’s first National Monument and remains important to tourists and the many tribes that hold it sacred.

Como Bluff in Carbon County and Albany County, Wyo., is the location of one of the world’s richest quarries of Jurassic dinosaur bones. Paleontologists found excellent dinosaur fossils in greater quantity here in the late 19th century than had ever been known before. These included Allosaurus, Diplodocus and Apatosaurus. Many of these specimens are still on display at the Peabody Museum at Yale University, the Smithsonian Institution’s National Museum of Natural History in Washington, D.C., and the American Museum of Natural History in New York City. The site is seldom quarried today, as most of the bones have been removed. Como Bluff is listed on the National Register of Historic Places.

Remains of at least seven mammoths, probably from a meat cache dating back more than 11,000 years, were found when the Colby Mammoth site east of Worland, Wyo., was excavated by a crew under Wyoming State Archaeologist George Frison in the 1970s.

Prospectors first struck oil in the Salt Creek Oil Field in northern Natrona County, Wyo. late in the 1880s. The first gusher came in in 1908. The subsequent boom lasted until the late 1920s, peaking in 1923, when the field produced more than 35 million barrels of oil. Tom Wall, who went to work in the field in 1917, stayed for decades and in the 1970s wrote out his memories of life in the oil patch through boom and bust. After 125 years and thanks to new technologies, the Salt Creek Field continues to produce today.

Anchor Dam was built in the 1950s on upper Owl Creek in Wyoming’s Bighorn Basin. The bedrock under the reservoir site is porous, and the reservoir has never held much water. The U.S. Bureau of Reclamation more than doubled its initial costs with subsequent mitigation efforts, which proved unsuccessful. The dam stands today high above a small pool of water.

Alcova Dam, a Bureau of Reclamation project, was completed in 1937. The reservoir opened in 1938 and a power plant was completed in 1955. The $20 million dam project didn’t achieve the high expectations of immense wealth that were forecast at the time of its inception, but continues to provide irrigation water for farmers and ranchers and generates hydropower for the area. Alcova Reservoir offers fishing, boating, camping and swimming opportunities for visitors.