Sinkholes arise from the motion of water underneath solid ground. The constant motion of the water breaks away the base of the solid land until there is nothing for it to rest on and it sinks in on itself. Florida houses many sinkholes because the entire land mass is technically below sea level. Commercial areas where there are many man-made structures and an underground water system cause sink holes if something goes awry with the pipes. The mass flow of water disintegrates the base and the structures collapse into a sinkhole.
Bornhardts were named for a German geomorphologist named Bornhardt in 1900. These formations contain at least one steep side and one dome-shaped side. The exfoliation of the formation occurs as weaker, surrounding rocks break away leaving the steep side. Another name for the formation is "exfoliation domes." Half Dome in Yosemite Valley is so famous it is featured on the back of the California quarter.
Canyons form when the constant weathering of flowing water breaks away the land around it. Slowly the canyons run deeper and wider as the land mass and rock flow to other areas. The Grand Canyon is a large example of this type of formation. Similar to a canyon is a Hoodoo. Hoodoos -- or rock pinnacles -- form from differential weathering, meaning weaker rock breaks away faster than stronger rock. Combination beds consisting of things such as limestone, sandstone and shale wear away at differing rates due to wind and water and towers of stronger rock are left behind. Bryce Canyon, Utah features many hoodoo formations.
The breaking away of rock might not seem like something that would cause land formations but this change in the surface causes mountain peaks and caves. Fields happen due to the constant freezing and thawing of water on the slope. As water condenses in crevices and freezes over the winter it expands, putting pressure on the rocks. When the thaw comes and the water sheds it leaves large cracks. For some of the rocks this is enough to break large pieces off, forming the jagged peak of a mountain or the rubble field at the base of the mountain. As the rubble field grows, it changes the course of water shed, snow build up and the overall shape of the mountain. Sometimes the rocks can fall in a way so as to form cave formations with other rocks.
