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LOCATION
Map Show Map
Address Lot 550 Princes Highway TANTANOOLA
Locality
Accuracy H - high level confidence
Council Area Wattle Range Council
Polygon Type P - parcel (from DCDB)
DESCRIPTION
Details (Known As) Green Waterhole - Tank Cave Fossil Complex [Designated as a place of palaeontological, speleological and geological significance]
Registered Name Green Waterhole - Tank Cave Fossil Complex
Significance The Green Waterhole - Tank Cave Fossil Complex contains the only known extensive underwater vertebrate fossil deposits in Australia. This unique freshwater depositional environment has ensured the preservation of extinct species not found anywhere else, with several additional species new to science recovered and awaiting description. The underwater deposits have also resulted in a completeness and preservation of fossil assemblies almost unique for Australia. This provides an important opportunity to investigate the evolution of South Australian mammals and birds. The impacts of this type of site on the age and nature of the fossil remains have yet to be fully studied. The complex represents unusual geological formations including the occurrence of a shallow fresh waterhole not usually found in sinkholes in the South East, and evidence of rare volcanogenic influences in the formation of the cave system. The cave complex also demonstrates rare speleological features, including length of cave passageways, clarity of water, underwater speleothems, and being a type locality for stygofauna. The complex also holds importance for the development of cave diving in the country and is closely associated with the Cave Divers Association of Australia. It is also acknowledged as a place of significance for the Boandik people. STATEMENT OF DESIGNATION *Designated Place of Palaeontological Significance The Green Waterhole - Tank Cave Fossil Complex is highly significant for palaeontology in three important ways. First, it is the best example of underwater Pleistocene vertebrate deposits anywhere in Australia. Although fossils of this age are found in underwater settings throughout the Mt Gambier region, fossils in the Green Waterhole - Tank Cave Fossil Complex are incredibly numerous, very well preserved, and found in situ. Second, the site contains fossil species found nowhere else in Australia, or else are incredibly rare. These include both bird and kangaroo species. Third, the site offers the rare opportunity to study the taphonomy of underwater deposits. Evidence for at least one wetting and drying phase in the cave has the potential to provide important information for understanding how fossil deposits are formed and preserved in cave settings. *Designated Place of Speleological Significance The Green Waterhole - Tank Cave Fossil Complex is situated at the Western end of the longest underwater cave system in South Australia, widely acclaimed as one of the premier cave diving localities in Australia. The Green Waterhole - Tank Cave system has a long history in the development of the sport of cave diving in Australia. In addition to the 10 kms of passageways that can be explored by divers, the complex preserves important speleological formations, features, and fauna that are rare or not found in other caves in the area. *Designated Place of Geological Significance The broad Gambier Limestone Plain extends from the coastline to the Bordertown/Kingston area and is a raised sea floor, elevated over 1-2 million years by tectonic forces associated with the volcanic activity across the region. Fresh groundwater from rainfall percolates through the limestone from inland to the coast, dissolving cave systems particularly along major fracture lines (geological faults). Volcanoes also have also erupted along two large regional faults in the Mount Gambier region. Many large deep sinkholes (`cenotes') have developed south of Mount Gambier reaching the water table and extending deep below them (50-120m). The combined Green Waterhole - Tank Cave system is shallow by comparison (20m) with other sinkholes in the region, and is the longest underwater cave system by far in South Australia, developed by solution in a large complex grid system (see site map overlay). Initiation and enlargement of the cenotes and possibly the Green Waterhole - Tank Cave system itself has been assisted by volcanic CO2 gases rising up fault lines and acidifying the groundwater, stimulating large-scale solution of passages in the limestone (Webb et al 2010). This is a rare process in global cave development known as `volcanogenesis' and requires the coexistence of volcanoes, extensive limestone and abundant groundwater, which occurs at this location. Ongoing research will establish if this process has been applied throughout the development of the Green Waterhole - Tank Cave system. Green Waterhole is a shallow cenote that is attractive to animals and humans, being more accessible for drinking during dry periods than most other sinkholes in the region. The waterhole made water available in a pool perched above the regional water table during low sea levels. The cave complex provides an excellent opportunity to study the relationship between changing sea-levels, ground water, and environment, and their effects on the evolution and extinction of fauna in the region over a long time period.
Subject Index Landscape area - Palaeontological Site; Landscape area - Speleological Site; Landscape area - Geological Site
Class State
STATUS
Status Code PRO - Provisionally entered as SH Place in the SA Heritage Register
Status Date 08-MAY-2025
REFERENCE
LGA Wattle Range
State Heritage ID 26530
Heritage Number 28119
SECTION 16 INFORMATION
Section 16 b - it has rare, uncommon or endangered qualities that are of cultural significance
c - it may yield information that will contribute to an understanding of the State's history, including its natural history
g - it has a special association with the life or work of a person or organisation or an event of historical importance
PLAN PARCEL & TITLE
As listed in the SA Heritage Register
Plan Parcel & Title Information CR 5762/955 H420600 S550,CT 6311/164 H420600 S488,CT 6075/536 D86241 A71

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