King Solomons Cave
These, however, are but two caves in an area that contains over 300 known caves and sinkholes, as well as gorges and large underground streams and springs. These features are characteristic of a "karst" landscape. "Karst" is a Slovene/German word which is used to describe landscapes that are developed principally by chemical processes rather than physical processes. Such chemical processes consist of the erosion of limestone rock by acidic water. (Water can become acidic as it moves through vegetation matter on the Earth's surface). While caves and caverns are characteristic features of karst areas, not all karst areas have caves.
Another feature of karst areas is the close relationship between the ground above and the below-ground environments. This means that above-ground activities such as vegetation clearing and the dumping of rubbish generally impact on the cave environment. Where soil is eroded it may be washed underground, clogging cave systems and even altering drainage from farmland paddocks.
How old are the caves?
Formations within Marakoopa Cave
(Photograph by Paul Flood)
The Mole Creek caves have a long and complex history. The limestone in which the caves have developed began forming in the Ordovician Period (400-500 million years ago). At that time, Tasmania, as part of Gondwana (a "supercontinent" comprising mainland Australia, South America, Antarctica, India and other southern landmasses) was closer to the equator and covered by a warm and mostly shallow sea. Limestone was deposited in this marine environment mainly as coral reefs, but also in a deeper sea where it formed as the result of the accumulation of microscopic marine organisms. Most of western Tasmania was covered by limestone during this time, but much of it was later covered by younger rock formations.
The processes that give rise to caves and karst features probably began relatively soon after the limestone was deposited. However, the caves we enjoy today started forming in more recent geological times - after streams had cut down through the rocks overlying the limestone at the ground surface.
Evolution of the caves in the Mole Creek area has possibly been influenced by the uplift of the Central Plateau to the south. As Australia began to break away from Antarctica and a circum-polar current was established, glaciers developed in Antarctica and the Tasmanian mountains. Glacial sediments were deposited in the Forth Valley around 30 million years ago and, particularly in the last two million years, there have been a succession of glaciations and intermittently episodes of less severe climate - such as that which we are now experiencing. Meltwaters from glaciers and snowfields probably actively formed some caves, but in other cases caves were blocked by the sediment swept into them. Remains of some of this sediment can be seen in the roof of Marakoopa Cave (above the Coral Gardens).
King Solomons Cave is regarded as a relatively dry cave as it has no stream running through it. A stream has previously flowed through the cave, which was important in the formation of the cave, but this has long since cut deeper into the limestone and abandoned King Solomons.
Life in the Caves
The streams that run into Marakoopa Cave carry many insects and large amounts of plant material which forms the basis of the food web for cave-dwelling animals. Many of these animals show fascinating adaptations for life in an environment where there is no light. Species which never leave their black homes are known as troglobites. As there is no light, troglobites have no need for eyes. Their long appendages, or feelers, help them find their way around.
The glow-worms in Marakoopa Cave are not worms at all, but rather the larval form of a mosquito-like fly. the light is produced by burning waste products in the larvae's excretory organs. Adult females also produce light to attract male flies. The glow-worm display in Marakoopa Cave is the largest you'll see in any public access cave anywhere in Australia.
Other species which occur in Marakoopa Cave include harvestmen, the Tasmanian cave spider and the ancient mountain shrimp (Anaspides).