Mississippian-age Waulsortian bioherms in the Lodgepole Formation are well exposed and accessible for field study in Swimming Woman Canyon, Big Snowy Mountains, Central Montana. Swimming Woman Canyon is east of Judith Gap, northeast of Harlowtown, and north of Rygate, Montana (Fig, 1). The site can be reached by automobile via gravel roads from U.S. 191 or from U.S. 12. Three routes to the site are shown. The route selected will depend on the direction the visitor is traveling. Travelers using the Judith Gap route may be tempted to continue east after driving 15 mi (24 km). Part of the...