Karst is an area of land made up of limestone. Limestone, also known as chalk or calcium carbonate, is a soft rock that dissolves in water. As rainwater seeps into the rock, it slowly erodes. Karst landscapes can be worn away from the top or dissolved from a weak point inside the rock.
Karst landscapes feature caves, underground streams and sinkholes on the surface. Where erosion has worn away the land above ground, steep rocky cliffs are visible.
Shilin is a karst formation in southern China. In Chinese, shilin means stone forest. Shilin got its name because the tall rocks that formed due to erosion look like stone trees. Shilin is part of a larger karst landscape called the South China Karst, which spreads across the Chinese provinces of Guangxi, Guizhou, and Yunnan.
In Mexicos Yucatn Peninsula, you can find cenotes, which are karst sinkholes that have filled with water. Sometimes, cenotes connect to waterways underground. Mexicans and tourists use the cenotes as cool, pristine swimming pools.

China's Stone Forest karst formation is a national park.
Photograph by Scott Milton, Your Shot
Underground Rivers
Underground rivers, also known as subterranean rivers, flow at least partly beneath the surface of the Earth. Many underground rivers are part of a karst landscape, where eroded limestone often creates caves. Underground rivers may emerge at sinkholes or above ground, as the karst landscape gives way to soil.
calcium carbonate
Noun
chemical compound (CaCO3) found in most shells and many rocks.
cave
Noun
underground chamber that opens to the surface. Cave entrances can be on land or in water.
cenote
Noun
natural sinkhole or reservoir where groundwater is available.
chalk
Noun
a soft mineral. Also called limestone and calcium carbonate.
dissolve
Verb
to break up or disintegrate.
erode
Verb
to wear away.
limestone
Noun
type of sedimentary rock mostly made of calcium carbonate from shells and skeletons of marine organisms.
rock
Noun
natural substance composed of solid mineral matter.
seep
Verb
to slowly flow through a border.
Shilin
Noun
karst formation in southern China. Also called the Stone Forest.
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