Kinds of Weathering of Caves

Chemical Weathering

• Chemical weathering refers to the decomposition of rock by chemical reactions. The type of chemical weathering most often associated with cave formation is carbonation, which is the dissolving of limestone by acidic groundwater. When carbon dioxide from the air becomes dissolved in water, it makes that water acidic. This water, if it falls on limestone, dissolves the rock. Carbonation is responsible for creating vast networks of limestone caves. The dissolved limestone is sometimes precipitated out of the water to form stalactites, stalagmites or columns inside the caves.

Physical Weathering

• Physical weathering is the disintegration of rock by mechanical forces. These forces often act along fractures or cracks in the rock. Physical weathering also breaks rocks into smaller pieces, which increases the surface area over which processes such as chemical weathering can occur. For example, physical weathering may occur when cracks in the rock are forced apart when water seeps into those cracks, freezes, and expands. This widening of the cracks provides a means for acidic groundwater to flow into the rock, leading to chemical weathering.

Erosion

• One form of physical weathering that creates caves is erosion. Erosional caves are formed when the wind or water carries abrasive sand particles capable of carving rock. Erosional caves can be found in almost any kind of rock, from hard granite to soft sandstone. Sandstone, in fact, is soft enough that it can be eroded by the action of sand particles carried by the wind. The caves created through this process can be large, but they are neither deep nor extensive.

Sea Caves

• Sea caves are formed through physical weathering, when waves enter a crack in a coastal cliff. The force of the water and the compression of air created by the waves then cracks the rock from within. Erosion also plays a role in the formation of sea caves, as the waves carry sand and small rocks that abrade the interior of the cave. Sea caves may be one of the most numerous types of cave, as they are found all over the world, wherever there is rock capable of holding a cave.