Boars Tusk, Volcanic neck in Sweetwater County, United States
Boars Tusk rises 400 feet above Killpecker Creek plain, forming a dark lamproite rock formation against the surrounding sandy landscape.
The volcanic structure dates back 2.5 million years, representing the eroded remnants of an extinct volcano within the Rock Springs Uplift.
The geological formation holds importance for multiple indigenous groups, including the Shoshone, Arapaho, Ute, Shoshone Bannock, Lakota, Cheyenne, and Apsáalooké nations.
Visitors need a high-clearance vehicle to access the site via US Highway 191 to mile marker 10, followed by County 4-17 and the Boars Tusk access route.
The formation contains lamproite, an uncommon volcanic rock type, making it a notable geological study site in Wyoming's Green River Basin.
Location: Wyoming
GPS coordinates: 41.96278,-109.19722
Latest update: March 16, 2025 01:04
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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