THESE DAZZLING ROCK FORMATIONS STAND WHERE DINOSAURS ONCE ROAMED

The big reveal occurred about six thousand years ago when the ice associated with the last ice age melted. The resulting flooding eroded the sandstone, exposing fossils, petrified wood and the limestone tubes. Time, wind and water continued artistic erosion, sculpting the layers of stone into the surreal fields of hoodoos and towers visible today. The western side of the Wilderness, formerly called the Bisti Wilderness, is primarily Fruitland Formation. The eastern side of the Bisti/De-Na-Zin Wilderness, formerly called the De-Na-Zin Wilderness, exposes the Kirtland Shale. Volcanic ash covers many of the features in the De-Na-Zin area.

The De-Na-Zin (eastern) side of the Wilderness looks like an undulating riverbed, with small and large channels winding around rounded hills. The area has more sand and less ash than the Bisti, with fewer hoodoos and higher hills. The exposed layers of shale coincide with the K/T boundary layer. The K-T boundary are the layers of rock reflecting the Cretaceous and Tertiary periods, formed about 65.5 million years ago. The Bisti/De-Na0Zin Wilderness Area is one of the few areas of public land in the world where the boundary layer is visible.

Based on relics found, it is estimated that humans have occupied the area almost continuously since 10,000 BC. Located less than 30 miles north of Chaco Canyon, the area contains numerous Chacoan sites and is crossed by the prehistoric Great North Road, which connected major Chacoan Anasazi sites in the San Juan Basin.