Fossil Cave (5L81), formerly known as The Green Waterhole, is a

cave Caves or caverns are natural voids under the Earth's Planetary surface, surface. Caves often form by the weathering of rock and often extend deep underground. Exogene caves are smaller openings that extend a relatively short distance undergrou ...

in the

Limestone Coast The Limestone Coast is a name used since the early 21st century for a Regions of South Australia#South Australian Government regions, South Australian government region located in the south east of South Australia which immediately adjoins ...

region of south-eastern

South Australia South Australia (commonly abbreviated as SA) is a States and territories of Australia, state in the southern central part of Australia. With a total land area of , it is the fourth-largest of Australia's states and territories by area, which in ...

. It is located in the gazetted locality of Tantanoola about north-west of the city of

Mount Gambier Mount Gambier is the second most populated city in South Australia, with a population of 25,591 as of the 2021 census. The city is located on the slopes of Mount Gambier (volcano), Mount Gambier, a volcano in the south east of the state, about ...

, only a few metres from the

Princes Highway Princes Highway is a major road in Australia, extending from Sydney via Melbourne to Adelaide through the states of New South Wales, Victoria (Australia), Victoria and South Australia. It has a length of (along Highway 1) or via the former ...

(Route B1) between Mount Gambier and Millicent. It is popular with cave divers and is notable for being both a unique

paleontological site A paleontological or fossiliferous site is a locality in which a significant quantity of fossils is naturally preserved in the rocks. The extent of the site is determined, in some cases, by the spatial distribution of the concentration of fossils ...

and the "type locality" for very rare crustaceans (syncarids - Koonunga sp.) which to date have been found only in caves and Blue Lake in the Mount Gambier region.

Description and naming

The cave is formed in 30-million-year-old Oligocene

coral Corals are colonial marine invertebrates within the subphylum Anthozoa of the phylum Cnidaria. They typically form compact Colony (biology), colonies of many identical individual polyp (zoology), polyps. Coral species include the important Coral ...

line

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

. The cave is a

karst Karst () is a topography formed from the dissolution of soluble carbonate rocks such as limestone and Dolomite (rock), dolomite. It is characterized by features like poljes above and drainage systems with sinkholes and caves underground. Ther ...

sinkhole A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. The term is sometimes used to refer to doline, enclosed depressions that are also known as shakeholes, and to openings where surface water ...

and is largely filled with water. The surface depression is about long and wide. Beneath the surface it extends to a maximum length of and a width of . The name of the cave was changed on 23 April 1989 by the

Government of South Australia The Government of South Australia, also referred to as the South Australian Government or the SA Government, is the executive branch of the state government, state of South Australia. It is modelled on the Westminster system, meaning that the h ...

from ''The Green Waterhole'' to ''Fossil Cave'' with the change being published in The South Australian Government Gazette on 4 May 1989.

Fossils

Since the mid-1960s, a variety of

Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

subfossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

material of birds and mammals has been found and recovered by divers from the surface of a

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to a depth of about below the water surface. The probable accumulation mode was by animals drowning when they fell into the cave while attempting to use it as a source of drinking water. Dating of the subfossil remains indicated that their deposition occurred mainly between 15,000 and 40,000 years ago. As well as representing many living animals, examples of extinct species recovered from the cave include the birds '' Centropus colossus'' and '' Orthonyx hypsilophus'', and the mammals '' Thylacinus cynocephalus'', '' Thylacoleo carnifex'', '' Propleopus oscillans'', '' Macropus titan'', '' Protemnodon anak'', and the sthenurine kangaroos '' Procoptodon gilli'', '' Procoptodon maddocki'' and '' Simosthenurus occidentalis''.

Exploration

Fossils were first collected from the cave in 1964 followed by a further collection in 1968 and logged with the

South Australian Museum The South Australian Museum is a natural history museum and research institution in Adelaide, South Australia, founded in 1856 and owned by the Government of South Australia. It occupies a complex of buildings on North Terrace in the cultur ...

. During the next two decades a number of more extensive surveying, sedimentology and bone-recovery operations were carried out by cave divers working in conjunction with palaeontologist Dr Rod Wells and researcher Cate Newton (Flinders University) and the South Australian Underwater Speleological Society (SAUSS) Inc. The cave's submerged extent has been surveyed at least three times including by the Flinders University Underwater Club (FUUC) in 1978, Allum and Garrad in 1979 and SAUSS in 1987.

Recreational diving

Fossil Cave is a notable cave diving site. Access for cave diving is limited to holders of the Cave Divers Association of Australia's Advanced Cave grade.

References

External links