Bisti Wilderness, New Mexico, 2016—When I got lost in Bisti in 2016, I found my way to this caprock, which I had remembered from my first visit in 2012. From here I knew where the parking lot was. In the gully next to this protuberant formation were the broken remains of other caprock extensions that couldn’t sustain the weight of their cantilevers after reaching a critical point in their erosion. This one will eventually face this fate too, and nothing will replace it. Caprocks are formed when a level of ground falls away, leaving the more tightly packed mudstone standing. It takes millions of years under water to build up the constituent sediment and millions more to wear it away to form these hoodoos once the waters recede.