Ah-Shi-Sle-Pah Wilderness Study Area is located in San Juan County, New Mexico between Chaco Canyon and the De-Na-Zin Wilderness. The Wilderness Study Area (WSA) has multicolored badlands, sandstone hoodoos, petrified wood and dinosaur bones, similar to those found in the nearby Bisti Badlands and De-Na-Zin Wilderness.
The BLM Wilderness Study Area was declared in May 1992, and would protect an area of about 26.5 km2. (6,563 acres) The area was prospected by the renowned dinosaur hunter Charles Hazelius Sternberg in the summer of 1921. [1] Sternberg collected the type specimen of Pentaceratops fenestratus, a ceratopsid dinosaur from the late Cretaceous Period, within the WSA. Specimens from this area form a significant part of the vertebrate paleontology collection at the Museum of Evolution, University of Uppsala, Sweden.[2] Note that fossil collecting here without a permit is prohibited by law.