Dillon Pass/Conata Basin

This view is from the historic Rainbow Overlook near Dillon Pass on the Badlands Loop Road. Brightly colored (gray, orange, pink, and white) mudstone, shale, and sandstone of the historically named “Interior Zone” and “Yellow Mounds” are part of the Late Cretaceous Pierre Shale and Fox Hills Formation.  These beds are overlain unconformably by the gray tuffaceous mudrocks of the Eocene Chadron Formation and the alternating red and pale gray tuffaceous sandstone and mudrocks of the Scenic Member of the lower Brule Formation (Stoffer, 2003).