Located between the NSW Central West towns of Orange and Cowra, the Cliefden Caves Geoheritage Site is unique, containing internationally significant Ordovician fossils, limestone caves, a warm spring, a habitat for threatened bat species and historical sites, including the first discovered limestone in inland Australia. It is ranked in the top 15 most significant limestone cave system in Australia by scientific experts.
With over 100 recorded caves, Cliefden Caves is one of the most cavernous limestone areas in New South Wales. The caves at Cliefden have a network pattern guided by geological structure in the Ordovician limestone. While they are located close to the Belubula River, there is no evidence that streams or the river have ever flowed through the caves. The caves show evidence of solution by rising groundwater, possibly related to the adjacent thermal spring. The caves are extremely well decorated with the full range of cave formations, the quality of which have been likened to the nearby Jenolan Caves. The caves contain rare blue stalactites, stalagmites, helictites and columns, and unusual mineral and mud deposits which are an important record of past environments. All caves at Cliefden are locked and gated for their protection, however speleological and scientific work is allowed under strict conditions.
The Cliefden Caves Limestone was the first discovered in inland Australia, being recorded on 24 May, 1815 during the explorations of surveyor G. W. Evans, only 2 years after the crossing of the Blue Mountains. Reference was also made to it by Oxley in 1817. The first land grants were taken up by Rothery brothers in 1832. The barn at the Cliefden homestead sports bullet holes from when the Rothery family was held up by the infamous Ben Hall gang in the 1860s! Caves have been known for over a century and were recorded by Wilkinson in 1892 and Trickett in 1908. The limestone was extensively mapped by Carne and Jones in 1919.
The invertebrate fossils at Cliefden have long been recognized as iconic examples of Australia’s paleontological heritage. The fossils are over 450 million years old and are remains of ancient marine animals. At least 62 scientific papers have been published in a variety of international journals, documenting 191 genera and 263 species of fossils from these and other sites in the vicinity of Cliefden Caves; of these, 45 genera and 101 species are unique to the area threatened by flooding. Some of the many ancient marine species that are preserved at Cliefden include trilobites, brachiopods, bryozoa and stromatoporoids.
A thermal spring is located on the Belubula River near the caves. It is one of only three thermal springs associated with karst in NSW. Warm springs rising from Palaeozoic rock (as opposed to those from the Australian Basin) are rare in NSW with only three documented, all in karst areas.