On a dry ridge above the desert near West Wendover, Nevada, sits a limestone arch cut by surf — waves of Pleistocene Lake Bonneville breaking against the rock roughly 17,500 years ago, near the ice-age lake’s maximum extent. At about 4,839 feet, the arch sits between the lake’s Bonneville shoreline (near 5,100 feet) and its later Provo shoreline (near 4,750 feet), meaning the water carved it before dropping further. It’s not the famous Arizona formation of the same name.