Hoodoos: What Three Million Years of Frost Does to Rock

What you are looking at took about three million years to make, and the process has not stopped. The hoodoos of Bryce Canyon are not finished.

The formation works in two stages. First: water seeps into cracks in the limestone and mudstone, then freezes. At Bryce's elevation, between eight thousand and nine thousand feet, that freeze-thaw cycle happens approximately two hundred times a year. Each cycle is a small act of wedging, widening the crack incrementally. Second: the upper layer of hard limestone resists erosion while the softer mudstone and siltstone beneath it weathers away faster, leaving the limestone perched on top of a narrowing column. That contrast between the cap and the pillar is what produces the shape you recognize.

The rim is not stable. It retreats at a rate of roughly one to four feet per century, and the hoodoos themselves are temporary. The columns you are looking at are further along in their erosion cycle than the ones behind you, and less far along than the ones that have already toppled and become the rubble at the base of the amphitheater.

John Wesley Powell sketched this landscape during his eighteen seventy-two survey of the Colorado Plateau. What he drew is measurably different from what stands here now. The Bryce Canyon amphitheater is among the most visually dynamic landforms in North America: not a monument, but a process. The tourists who photograph it today are documenting a moment in a sequence that began before the first humans arrived in North America and will continue long after the last road into the park has crumbled.