Green River Buttes

“Throughout the Green River Basin, many “elevated buttes of singular configuration” rise from the rolling plains, sticking up like flat-topped warts on a sagebrush skin. They stand several hundred feet high, with eroded edges that descend in irregular steps. A closer look reveals that the jutting ledges are made of layers of beige sandstone and off-white limestone, while the soft slopes are comprised of tan, green, and rusty-brown mudstone. To Edwin Bryant, the buttes looked like islands. “The plain appears at some geologic era to have been submerged, with the exception of these buttes, which then were islands, overlooking the vast expanse of water.” Bryant was wrong about the islands, but right about the water. The Green River Basin was once the site of an immense lake. The buttes are the eroded remains of once-continuous sedimentary layers that blanketed the lake’s floor.”