Karst (limestone cave) landforms have been weathered out of the limestone by seepage from the surface. There are some massive caves in the world's largest block of limestone. The water table is reached by a lot of the larger deep caves, and where it does there are often clear lakes and complex networks of underwater passages. The deeper caves often have very large caverns, up to hundreds of metres long. The flat floors are usually strewn with piles of fallen rocks and many have high domed ceilings.
Karst topography is formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum. Karst is characterised by underground drainage systems with sinkholes and caves. Carbonic acid that causes karst features is formed as rain passes through the atmosphere picking up carbon dioxide. Once rain reaches the ground it forms a weak acid solution, which dissolves calcium carbonate and forms cave systems
Koonalda Cave is a crater-like doline (limestone sinkhole) in the karst of the Nullarbor Plain. The sinkhole gives no indication of its presence. As it is approached you will see a large opening flush with the surrounding plain. The walls of the sinkhole are sheer vertical sides or undercut. Behind a locked door is a steep slope to the main chamber. This chamber is huge, larger than the opening you can see. Two passages lead from the main chamber, one of which leads to three underground lakes.
For the original peoples of this land there were two major attractions in this cave, reliable water and a plentiful supply of flint. Large flat areas of the chamber and passage walls are covered with random crisscrossing parallel finger markings. Indigenous artwork that has been dated as 20,000 years old, making it older than any known prehistoric cave art in Europe.
It is not possible to enter the cave system without permission. Visits to caves on the Nullarbor are restricted to speleological (caving) clubs, and for research, monitoring and management. From the visible surface features please provide answers for the following two tasks.
=>Has the doline formed by collapse of a chamber or water dissolution?
=>Is there evidence of recent collapse? What do you see?