Cultural Geology Guide—Pumpkin Buttes

Cultural Geology Guide—Pumpkin Buttes

Pumpkin Buttes and Uranium Fever

PUMPKIN BUTTES WYOMING –These buttes contain uranium created from the ash of volcanic eruptions some 50 million years ago. This is the site where, in 1951, J.D. Love first discovered uranium in a Wyoming sedimentary basin. Love’s discovery led to uranium fever: Prospectors and ranchers postured for potential stakes. What historian T.A. Larson calls “the complex pattern of rights to land and minerals” in Wyoming led to confusion in all directions.

Cultural Geology Guide—Pumpkin Buttes
J.D. Love


Pumpkin Buttes

There are many stories about just how Pumpkin Buttes received its name. It may have been because of the shape of the buttes and color resembling pumpkins. They were also called Wa-ga-mu Paha (Gourd Hills) by Sioux Indians, named because of a tribal ceremony held there in which gourds were rattled.

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It has also been speculated the name was derived from the pumpkin-sized iron concretions found below the buttes that were likely processed for uranium. Another theory is Jim Bridger named the buttes after wild pumpkins growing there. One thing is for sure, it is the site where in 1951 famed geologist J.D. Love first discovered uranium in a Wyoming sedimentary basin.

The history books also note that the three large, flat-topped mountains were used as landmarks by early travelers and as a hideout by Big Nose George Parrot and his gang. Big Nose George was finally hanged by vigilantes at Rawlins, after he tried to wreck and rob a Union Pacific train by pulling the spikes from the rails. A section boss discovered some loose rails and flagged the train down. The gang fled to Montana, where Big Nose George was finally caught.



The Cold War: The Atomic Age

In 1948, with tensions increasing between the United States and Russia at the start of the Cold War, the Atomic Energy Commission (AEC) issued a series of circulars providing for the procurement of uranium ores, setting minimum prices, bonuses for the discovery of new deposits, and other incentives for high-grade ores, haulage allowances, etc. With such payoffs, prospectors began scouring Wyoming for uranium ore.

Around the same time, uranium was discovered in 1949 in the Black Hills of Crook County. Also around that time, USGS geologist J.D. Love was pursuing the locations of uranium ore with his geologic research. He took to the air to conduct an aerial check of uranium in the Pumpkin Buttes portion of the Powder River Basin in southern Campbell County. Along with his colleagues, he conducted on-the-ground fieldwork to confirm what he had noted as uranium “hot spots.”

Prior to the 1950s, geologists believed that uranium deposits originated from hydrothermal activity. But U.S. Geological Survey geologists Denson, Bachman and Zeller hypothesized that uranium came from thick volcanic ash beds that covered Wyoming’s landmass more than 50 million years ago. The beds were laid down by eruptions of ash from the once volcanic mountains that now make up the Absaroka Range in northwestern Wyoming.

Love, who was researching this volcanic ash theory, decided it was time to see if it would produce results. In 1951, he was the first to discover uranium in a Wyoming sedimentary basin at Pumpkin Buttes. The flanks of Pumpkin Buttes indeed had very impressive concentrations of uranium. The find was important geologically as it appeared to verify the hypothesis of ash-sourced uranium deposits. Now it appeared that uranium could possibly exist in nearly all parts of the state.

Since then, uranium has been discovered in porous and sedimentary rocks in the Powder River, Great Divide, Wind River, and Shirley basins. In addition, there are significant uranium deposits in the western Black Hills area in northeastern Wyoming, the Little Mountain area of the northern Bighorn Range, and the eastern Greater Green River Basin. As a result of Love and other discoveries, Wyoming is home to the largest uranium ore deposits in the world.

Pumpkin Buttes