Landform

Although erosion and deposition are most easily observed where solid sediment is being moved about, invisible chemical reactions also produce landforms. As water moves through the soil it becomes acidic, in part because of the addition of carbon dioxide produced by the decay of organic matter. This weak acid is able to dissolve some kinds of rock, particularly limestone, giving us spectacular underground caverns, such as the Carlsbad Caverns of New Mexico. If such caves develop near the surface they often collapse, and a landform called a sinkhole develops above the cave-ins.

After passing through limestones, the water often becomes saturated with calcium carbonate. If it comes to the surface in springs, the calcium carbonate may precipitate to build up mounds of travertine, such as those in Saratoga Springs, New York. Similar travertine deposits can develop in arid climates when evaporation brings about the precipitation of calcium carbonate. Sometimes these form a series of little dams holding back pools of water, such as at Mooney Falls in the Grand Canyon, Arizona.