"From 500 to 570 million years ago" . . . . . . "Isopach and selected lithofacies map of the Cambrian Bonneterre Formation, Rolla 1° x 2° quadrangle, Missouri"@en . . . "Cambrian Bonneterre Formation. Rolla 1° x 2° quadrangle, Missouri"@en . . . . . "Maps"@en . . .