Natural Bridges National Monument, in southeastern Utah, is the site of three natural sandstone bridges spanning a streambed. Formed about 180 million years ago when flash floods eroded canyon walls, the bridges exist within 8 km (5 mi) of each other. Originally named Edwin, Caroline, and Augusta, they are now known, respectively, by the Hopi names of Owachomo, Kachina, and Sipapu. Sipapu, 66.6 m (222 ft) above the streambed with a span of 80.4 m (268 ft), and Kachina, 63 m (210 ft) high with a span of 61.8 m (206 ft), are believed to be the second and third largest sandstone arches in the world. Owachomo, though the smallest of the three, is believed to be the oldest. The 3,090-ha (7,636-acre) monument, established in 1908, protects Anasazi caverns, rock art, and cliff dwellings in the canyon below, as well as the surrounding canyons, where pinon pines, cottonwoods, willows, and Utah junipers abound.