Limestone reaches the surface and gets subject to weathering.
Ground water starts with the solution of limestone and forms first
caves.
A lower drainage system around the limestone area is necessary for the
second stage: the rivers and lakes leave the surface, drainage of the
whole area is underground.
This is the "typical" stage of a karst area, which we know well from
moderate climate zones.
The limestone caves get bigger and bigger and start to collapse.
Cave systems are marked at the surface by daisy chains of dolines.
Dolines merge and form poljes.
The cave systems are more or less collapsed.
The former poljes grew and grew until they are all connected and again
form a net of subaerial valles draining the area.
The former limestone plateau is cut into isolated limestone islands.
