How do desert rock formations like hoodoos form?

Hoodoos are slender rock spires found in arid and semi-arid landscapes, often with a harder capstone on top. They form when wind, rain, and freeze-thaw weathering wear away weaker layers of rock more quickly than the resistant layers. Over long periods, the differential erosion leaves isolated columns that can look like stone towers or mushrooms. Places such as Bryce Canyon in Utah are famous for their hoodoos, though the process can occur in many desert regions. Their shapes are continually changing as erosion slowly reshapes the landscape.