Ah-Shi-Sle-Pah Wilderness Study Area – Bloomfield, New Mexico - Atlas Obscura
Join us on an Atlas Obscura Trip in 2019 »

Bloomfield, New Mexico

Ah-Shi-Sle-Pah Wilderness Study Area

The land is full of geologic eye candy like otherworldly spires, mushroom-shaped hoodoos, and prehistoric fossils. 

With its muted colors and striking geology, this unusual landscape feels like a martian planet. Pale, mushroom-shaped hoodoos loom above the rocky earth like enormous alien trees. Petrified tree stumps and ancient bones speckle the badlands like prehistoric markers of its long-gone inhabitants.

Located in the arid San Juan Basin of northwest New Mexico, the Ah-Shi-Sle-Pah Wilderness Study Area is located on 6,563 acres of public Bureau of Land Management land. It’s a hidden wonder of weathered rock formations often referred to as hoodoos (not to be confused with witchcraft or the evil eye), tent rocks, fairy chimneys, earth pyramids, or mushrooms.

Geologically, the area is comprised of layers of sandstone, shale, mudstone, and bituminous coal that were deposited 75 million years ago during the late Cretaceous era. A whopping 75,000 millennia of wind, water, and ice weathering and eroding the layers are responsible for the surreal and alien-esque landscape.

Because of its geologic age and climate, the area is rich with animal and plant fossils. The remains of prehistoric crocodiles, turtles, fish, and dinosaurs are sprinkled throughout the land. You’ll also see petrified wood, including numerous upright tree stumps with roots.

While it’s somewhat challenging to get there, visitors are rewarded with a tranquil, if not dreamlike, environment which is easy to navigate. Although the formations extend for six miles along the Ah-Shi-Sle-Pah Wash, the most accessible and picturesque formations are within one to two miles of the parking area and can be seen within half a day of easy walking along the generally flat terrain.

Know Before You Go

This is relatively obscure and remote. It's unlikely you'll encounter other visitors. While the drive there includes almost 15 miles of unpaved road, a high clearance vehicle might be desirable only for the final 0.6 miles (you can walk this last stretch if your car can’t make it).


From Bloomfield, New Mexico, take US 550 south to NM 57. Turn right and take NM 57 for 18.3 miles (the first 4.9 miles are paved) to a two-track on the right. It’s 0.6 miles to the parking area and the take-off point for hiking.


This is Bureau of Land Management land. There are no trails or signs. A good GPS might be helpful in finding your way back to the car. The dirt roads and clay you will be hiking on become very slick when wet, so be mindful of the weather. You are pretty much out in the middle of nowhere (it’s 20 miles to the US highway), and there is no cell coverage. Bring water.


This area is rich in fossils. Regarding collecting, BLM regulations apply. Common invertebrate fossils such as plants, mollusks, and trilobites may be collected for personal use in reasonable quantities. Interestingly, petrified wood up to 25 pounds per person per day may be collected. Cultural artifacts and vertebrate fossils, including dinosaur bones, cannot be taken under any circumstances and must be left in place.