Fossil Cave (5L81), formerly known as The Green Waterhole, is a cave in the Limestone Coast region of south-eastern South Australia. It is located in the gazetted locality of Tantanoola[1] about 22 kilometres (14 miles) north-west of the city of Mount Gambier, only a few metres from the Princes Highway (Route B1) between Mount Gambier and Millicent. It is popular with cave divers and is notable for being both a unique paleontological site 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 corallinelimestone. The cave is a karstsinkhole and is largely filled with water. The surface depression is about 20 metres (66 ft) long and 10 metres (33 ft) wide. Beneath the surface it extends to a maximum length of 70 metres (230 ft) and a width of 30 metres (98 ft).[3]
Fossils were first collected from the cave in 1964 followed by a further collection in 1968 and logged with the South Australian Museum. 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.[3][7]
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.[3][8][9][10]