The influence of slaking susceptibility of rocks on the formation of hoodoos in Drumheller badlands, Alberta, Canada

Formation of mushroom-shaped rocks called "pedestal rocks' or "hoodoos', was examined through measurements of rock properties in the field and laboratory. Each hoodoos was morphologically divided into two parts: caprock and pillar. Morphological characteristics correspond to different rock types. The caprock is made up of sandstone with a high resistance to slaking, while the pillar is of sandstone and siltstone, with a low resistance to slaking. The difference of these rock types in susceptibility to slaking stems from pore-size distribution and clay mineral composition. These findings suggest that the formation of hoodoos in the study area is mainly controlled by susceptibility to slaking. -from English summary