Shell Falls is a 120-foot waterfall on Shell Creek in Wyoming’s Bighorn National Forest, about halfway down Shell Canyon and a few miles upstream from Shell, where the creek spills over exposed granite basement rock. The site is especially notable for making the canyon’s deep geology easy to see: Cambrian Flathead Sandstone, about 550 million years old, rests directly on Precambrian rocks dated to about 2.9 billion years ago, among the oldest visible on Earth. With canyon views and the prominent limestone outcrop called Copman’s Tomb to the north, Shell Falls stands out as both a scenic landmark and a remarkable window into ancient rock history.