Geology & Natural History

Natrona County’s Salt Creek Field is best known of Wyoming’s early oil fields, but five others—two in Park County and one each in Hot Springs, Niobrara and Converse counties—played important roles in the state’s 20th century transformation from an agricultural to an industrial economy.

Wyoming's fossils have been important to science since the 1870s and continue to be useful today. Remains of Triceratops, Diplodocus, Tyrannosaurus and others have helped answer—and raise—many questions about the ancient history of the planet and have captured popular imagination with their size or fierce appearance. The scientific value of these fossils and the public interest in them has brought collectors who excavate fossils and ship them to museums all over the country for further study and display. Only a few major finds from Wyoming have remained in the state.

The story of uranium in Wyoming is a high-stakes drama whose cast includes fever-driven prospectors, ranchers defending their property rights, government officials intent on national security, entrepreneurs, engineers and world-class mining companies.

When Thomas Boylan started collecting dinosaur bones on his homestead in 1915, he first envisioned completing a dinosaur skeleton and using it to attract customers to his gas station on U. S. Highway 30 near Como Bluff. However, he was told that he didn’t have enough bones for that. Instead, he used more than 5,700 bones to build a structure that has become known worldwide as the Fossil Cabin. The historic Fossil Cabin was built in 1932 and stands about five miles east of Medicine Bow, Carbon County, Wyo. The cabin has been featured in Ripley’s Believe It or Not! and is listed on the National Register of Historic Places.

The Powder River Basin sports a colorful history. Bones of bison slaughtered by people, found south of Sundance, Wyo., date back 6,000 years, and northeast Wyoming remained a favorite hunting ground for American Indians into the late 19th century. At that time the Powder River Basin was the scene of violent conflicts between the Indians and U.S. military men. Abundant grass made this region a favored spot for cattle and sheep ranchers. Under the grass is coal—so much of it that about 40 percent of the coal mined in the U.S., comes from the Powder River Basin.

Oil seeps were reported often in the early 19th century in what later became Wyoming; it was sold, for example to Oregon Trail travelers for wagon lubricant. The first producing well in Wyoming Territory was drilled in 1883 at Dallas Dome southeast Lander. Perhaps the state’s best-known historic oil producing region is the Salt Creek Field, north of Casper, which was one of the world’s largest-producing fields in the 1920s. Oil remains an important part of Wyoming’s economy and culture today, and the state is ranked high among the top national producers.

The basin of the North Platte River takes up the southeastern quarter of Wyoming, plus a finger of land along the tributary Sweetwater River in the center of the state. The courses of the North Platte and Sweetwater determined early fur-trade and emigrant routes. Since that time, the basin’s water and other resources have continued to draw industry, stock raising, dams and irrigation—and people.

Natural gas has been flowing from the Jonah Field and Pinedale Anticline in western Wyoming since the early 1990s, bringing with it substantial profits, tax revenues, prosperity, social change, air pollution, and declines in local mule-deer populations. The story goes to the heart of Wyoming’s oil and gas culture, and raises important questions about energy production’s long-term costs and benefits.

Western Wyoming’s Green River drains 4,000 miles of forested mountains and high desert, home to migrating wildlife, grazing cattle, a few thousand people, and in recent decades a booming natural-gas business. Since prehistoric times, people have worked to balance the basin’s resources for their own benefit — and that struggle continues today.

In 1843, explorer John C. Frémont reported coal in what’s now southwest Wyoming. In the 1860s, the route of the new transcontinental railroad across Wyoming was chosen partly to access abundant coal deposits for fuel for the locomotives. Coal mining boomed, labor strife increased and Wyoming’s coal industry thrived despite worker strikes and a number of horrific mine accidents. Today, the state produces 40 percent of the nation’s coal, most of it from huge strip mines in the Powder River Basin in northeast Wyoming, for rail shipment to electric power plants in 34 states.