Dolines may form a catchment, which may be crucial in their later development. A natural cavity in rock, large enough to be entered by people. May be water filled. May also be blocked partly or fully by sediment or ice. Commonly formed by solution in Limestone.
Caves also form in many other rock types, and by many other processes.
Cave - Kinds of . Cave - Parts of . Ref MM CAVE AGE Most karst cave passages are less than 1 million years old, though Relict Caves could be hundreds of millions of years old. The most recently formed passages may be as little as 10,000 years old. Speleology term .