Boars Tusk, Volcanic neck in Sweetwater County, United States
Boars Tusk is a volcanic neck that rises roughly 400 feet above the surrounding plains near Killpecker Creek. Its dark lamproite rock contrasts sharply with the light-colored sandy terrain that spreads around it in all directions.
This formation was created roughly 2.5 million years ago as part of an extinct volcano within the Rock Springs Uplift area. Erosion gradually removed the surrounding rock over millions of years, leaving only this isolated core standing today.
The geological formation holds importance for multiple indigenous groups, including the Shoshone, Arapaho, Ute, Shoshone Bannock, Lakota, Cheyenne, and Apsáalooké nations.
The best time to visit is during warmer months when roads are dry and passable. A vehicle with high ground clearance helps navigate the access routes that lead to the site from US Highway 191.
Lamproite is a rare volcanic rock that forms only in specific geological conditions found in few places worldwide. This location serves as a natural laboratory for geologists studying this uncommon mineral composition.
Location: Wyoming
GPS coordinates: 41.96278,-109.19722
Latest update: December 6, 2025 17:43
Wyoming preserves geological sites that include thermal springs, canyons, and rock formations. The state protects historic locations such as forts, rock art, and dinosaur tracks. Devils Tower rises 1,267 feet (386 meters) above the terrain and represents a significant geological formation. Fossil Butte conserves Eocene-era fossils in a former lakebed. Independence Rock served as a landmark for Oregon Trail travelers, while Fort Phil Kearny documents 1860s military history. The landscape includes waterfalls such as Popo Agie Falls and Jenny Lake Hidden Falls, mountain passes like Sylvan Pass, and Wind River Canyon. The Bighorn Medicine Wheel consists of stones arranged in a pattern on Medicine Mountain. Castle Gardens and Legend Rock display prehistoric petroglyphs. Red Gulch preserves dinosaur tracks more than 100 million years old. Sinks Canyon demonstrates a geological phenomenon where the Popo Agie River disappears into limestone caverns. Nature parks, hot springs like Granite Hot Springs, and forest areas such as Medicine Bow-Routt National Forests provide access to these areas.
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