Tunnel Creek National Park
Western Australia's oldest cave system, in Tunnel Creek National Park, is famous as a hideout used late last century by an Aboriginal leader known as Jandamarra. He was killed outside its entrance in 1897.
Tunnel Creek flows through a water worn tunnel beneath the limestone of the Napier Range, part of the 375 to 350 million-year-old Devonian Reef system. You can walk 750 metres through the tunnel to the other side of Napier Range, wading through several permanent pools and watching for bats and the stalactites that descend from the roof in many places. At least five species of bat live in the cave, including ghost bats and fruit bats, and stalactites descend from the roof in many places. Freshwater crocodiles are occasionally found in the pools. Take a torch, wear sneakers and be prepared to get wet and possibly cold.
The limestone reef is made up of calcium carbonate, which is readily dissolved by rainwater seeping from the surface into the rock. Over many thousands of years, water flowing along cracks, joints and bedding surfaces dissolves the limestone away, opening them out to form caves. Cave systems have formed wherever the reef has been exposed at the Earth's surface. This first occurred 250 million years ago, and the present system of active caves may have reused the same channels they created over the last 20 million years or so.
Tunnel Creek follows a prominent joint through the limestone. A old river valley on top of the range formed at a time when the climate was wetter, and the water table (the level to which rock beneath the surface is saturated with ground water) was higher. Erosion has since exhumed the reef, preserving the old river course.
The presence of underground pools along the floors of the cave is due to the water table being just below the present erosion surface. Water only flows through the cave after prolonged heavy rain during the wet season. During the dry season, water dripping from the roof of the caves and onto the floor precipitates calcite to form stalactites and stalagmites, or flows down the walls to form curtains of flowstones.
Tunnel Creek National Park covers just 91 hectares. It is 115 kilometres from Fitzroy Crossing, 180 kilometres from Derby, 30 kilometres south-east of Windjana Gorge.
Travelling time:
Two and a half hours from Fitzroy Crossing and two and a half hours from Derby.
Cave exploration, sightseeing, walking and photography.
Tunnel Creek is a day use area with facilities limited to toilets and an information shelter. *Note: Camping is not permitted in this area.
Suitable footwear is recommended, as well as carrying a torch.
The best season to visit is between May and September and the park is usually inaccessible during the wet season.