Wheeler Amphitheater, Millard County, Utah, USAi

Regional Level Types
Wheeler Amphitheater	Group of Gulchs (Paleo feature)
Millard County	County
Utah	State
USA	Country

Trilobites are probably the most common fossils collected in Utah, many world-class specimens from this state reside in museums throughout the world. In Utah, trilobites can be found at several localities.

House Range
The Wheeler Amphitheater in the House Range, Millard County is one of the more well-known collecting areas. Most of the trilobites in this area come form the Middle Cambrian formation called the Wheeler Shale. The Wheeler Shale contains interbeds of shaley limestone, mudstone, and thin platy limestone. Another trilobite-bearing unit that directly overlies the Wheeler Shale in the central part of the House Range is the Marjum Formation. This formation consists of thin-bedded, fine-grained, silty limestone with interbeds of shale and mudstone.

Also located in the central part of the House Range is a fossiliferous limestone called the Weeks Formation, that crops out in North Canyon near Notch Peak. The Weeks Formation overlies (is younger than) the Marjum Formation and also contains trilobites.

Wellsville Mountains
Another trilobite-bearing unit is the Spence Shale Member of the Langston Formation in the Wellsville Mountains, Box Elder County. Here, trilobites can be found in Miner’s Hollow, Cataract Canyon, Dry Canyon, and the area between Antimony and Hanson Canyons.