Encyclopedic Entry

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.

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.

Vocabulary

Term Part of Speech Definition Encyclopedic Entry

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.

cliff

Noun

steep wall of rock, earth, or ice.

Encyclopedic Entry: cliff

dissolve

Verb

to break up or disintegrate.

erode

Verb

to wear away.

karst

Noun

landscape made of limestone.

Encyclopedic Entry: karst

landscape

Noun

the geographic features of a region.

Encyclopedic Entry: landscape

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.

sinkhole

Noun

hole formed in a rock or other solid material by the weight or movement of water.

Encyclopedic Entry: sinkhole

stream

Noun

body of flowing water.

Encyclopedic Entry: stream

For Further Exploration

Websites

Credits

Media Credits

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Writer

Kim Rutledge
Melissa McDaniel
Diane Boudreau
Tara Ramroop
Santani Teng
Erin Sprout
Hilary Costa
Hilary Hall
Jeff Hunt

Illustrator

Tim Gunther
Mary Crooks, National Geographic Society

Editor

Kara West
Jeannie Evers

Educator Reviewer

Nancy Wynne

Producer

Caryl-Sue, National Geographic Society

Sources

Dunn, Margery G. (Editor). (1989, 1993). "Exploring Your World: The Adventure of Geography." Washington, D.C.: National Geographic Society.

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