Hoodoos aren’t unique to Utah; they’ve found in many other places in the world and also in a few other regions of the United States. However, there’s nowhere on the planet where they’re more plentiful than Bryce Canyon National Park.
To get hoodoos, you first have to start with the right kind of stone. The hoodoos at Bryce are formed from rock in the Claron Formation, which includes siltstone, mudstone and lots of limestone.
The various hardness and softness allows for different rates of erosion, making some spots more thin, while leaving other places on the hoodoo thicker.
The National Park Service states that hoodoos are differentiated from spires or towers by their curvy, totem-pole shape. The hoodoos at Bryce range from 5 to 150 feet tall. They’re formed by two types of erosion: frost wedging and rain.
Frost wedging has the most impact on the hoodoos at Bryce, which has over 200 freeze/thaw cycles each year. In the winter, daytime sunshine melts the snow, causing water to run into the cracks in the stone. At night, the water freezes again, expanding as much as 10%, which gradually forces the cracks in the rock to widen.
The hoodoos at Bryce get their curvy features thanks to slightly acidic rain. The rain melts away the limestone one grain at a time, curving and softening the features of each bulge.
Erosion continues to chip away at the Bryce hoodoos; the rate at the park is calculated at about 2-4 feet of erosion every 100 years. Visitors can help keep the hoodoos intact by staying on marked trails. Even standing right next to a hoodoo can shorten its lifespan because the tracks weaken the base that supports the hoodoo.