Landforms produced by the chemical weathering (carbonation) and solution of soluble rocks, chiefly limestone, by slightly acidic water; named after the Karst region of the Balkans.
- Surface features include sinkholes (dolines), swallow holes, lapies (grooved rock surfaces), and karst windows; rivers may disappear underground.
- Underground, caves and caverns form where water dissolves limestone along joints.
- Within caves, dripstone deposits form as water evaporates and redeposits calcium carbonate: stalactites grow down from the ceiling and stalagmites grow up from the floor; when they join they form a pillar or column.
- Karst develops best in thick, well-jointed limestone in humid climates; the process is carbonation, a form of chemical weathering.
- In India, karst and cave features occur in limestone areas such as the Borra Caves (Andhra Pradesh) and parts of Meghalaya.
The stalactite versus stalagmite distinction, the term karst, and the carbonation mechanism are standard objective items linking weathering to landforms.
Stalactite (hangs from ceiling, "c" for ceiling) versus stalagmite (rises from ground, "g" for ground); sinkhole (surface depression) versus cave (underground); karst is from chemical solution, not physical erosion.
Limestone dissolved by acidic water gives caves, sinkholes, and dripstone (stalactites down, stalagmites up).