Eroded granite at the Remarkable Rocks formation, on Kangaroo Island, Australia. This is an example of tafoni (or cavernous) erosion, which takes place at coastlines with high temperature and humidity differences and a high salt content in the air. It is a combination of physical and chemical weathering processes, and starts when water brings dissolved minerals to the rock surface. When the water dries, the minerals form crystals that force small particles to flake off the rock. Eventually, large cavities form that have a cavernous and honeycombed shape because the surface layer of rock is harder than the interior.