Mountains, Belt Butte, and the Great Falls Coal Field

The panel calls the Belt rocks hundreds of millions of years old; they are more than a billion. Most of the Supergroup was laid down between about 1,450 and 1,400 million years ago, more than fifteen kilometers thick; in Canada it is the Purcell. The name entered geology in 1893, when A. C. Peale called the strata the Belt formation in a Geological Survey paper on the Three Forks section, measuring them ten to twelve thousand feet thick in the Big Belt Range. Its basal unit is named for the silver town up US-89: the Neihart Quartzite.

Where it stands

Worth the stop nearby

• Giant Springs State Park — 20 mi
  The spring William Clark called the largest he ever saw, and the 201-foot river a fifth-grade class got into the record books.
• C. M. Russell Museum — 21 mi
  The cowboy artist's house and log studio, and the story of Nancy Russell, who turned his bar-tab paintings into a career.

More markers nearby

• Belt Commercial Historic District — 3.0 mi
• Coal Mines and Railroads — 13 mi
• Lewis & Clark Portage Route — 18 mi
• Malmstrom Air Force Base — 18 mi