Karst

definition: 
Landscape underlain by limestone that has been eroded by dissolution, producing ridges, towers, fissures, sinkholes, and other characteristic landforms.
sentence: 
The underlying limestone karst topography allows water to flow in abundant underground rivers, feeding the numerous springs, which flow into the many creeks and streams.
difficulty: 
easy
toefl frequency: 
2
toefl classification: