Eroded badlands of Bisti/De-Na-Zin Wilderness, south of Farmington, in San Juan County, New Mexico, USA. This fantasy world of strange rock formations is made of interbedded sandstone, shale, mudstone, coal, and silt. These rock layers have weathered into eerie hoodoos (pinnacles, spires, and cap rocks). This was once a riverine delta west of an ancient sea, the Western Interior Seaway, which covered much of New Mexico 70 million years ago. Swamps built up organic material which became beds of lignite.