Erosional features of underground water

Groundwater erodes mostly by solution, working on soluble rocks (limestone, dolomite, gypsum). The landscape is called karst topography. Features:

• Sinkholes (dolines): closed depressions made by dissolution or by collapse of a cave roof.
• Caves and caverns: underground hollows enlarged along joints and bedding planes.
• Sinking streams and underground rivers, springs.
• Lapies (karren): grooves and ridges on exposed limestone.
• Uvala and polje: large, compound sinkholes and wide valley-like basins.
• Natural bridges and dry valleys.