International Day of Caves and Karst!

Caves

Caves are natural, humanly enterable underground cavities. They occur around the world and on every continent. Caves vary in size, shape, and contents, with their geologic setting and mode of origin, known as speleogenesis, controlling these factors. Caves fall into two major categories: karst and pseudokarst. Karst caves are generally the most common, longest, deepest, and largest, although long, deep, large and important pseudokarst caves are also known.

Karst Hydrology

Karst waters mostly flow in the subsurface. The highly permeable rocks in karst regions result in surface water moving underground rapidly and becoming groundwater. There are some exceptions, such as poljes and river canyons, but these are small areas in comparison to the size of the karst landscapes in which they occur. In contrast, non-karstic regions with less- or poorly-permeable rocks are crossed by networks of rivers. In karst areas, water flows into the subsurface through open fractures, caves, and dolines.

Surface Phenomena

Karst rock formations on the surface are formed through dissolution during direct contact between rainwater and the rock on the surface or the rock buried under soil. The karst features that form on a rock surface depend on the amount of water that falls or flows over the rock, the type of rock, the presence or absence of soil and vegetation, as well as the steepness of the slope. Land surfaces in karst areas can vary greatly. Many karst areas have few or thin soils, creating rocky surfaces that are impossible for agriculture and are even difficult to cross.

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