Leeuwin-Naturaliste National Park

Margaret River Caves - Augusta Caves

The Leeuwin-Naturaliste Ridge is located between Cape Naturaliste and Cape Leeuwin. Precambrian crystalline rocks like granulite and granitic gneiss are visible at many headlands along the coast. They are between 650Ma and 2Ga old. This hard, insoluble rocks are capped by very young limestone, which is karstified. The Aeolian calcarenite covers area approximately 90 km long and 3 km wide, It was formed by the wind, as the name says, when westerly winds blew beach sand, sea-shells and corals into huge sand dunes. Rainwater dissolved and precipitated little amounts of limestone from the sand and thus cemented the sand together to form limestone, or better carbonatic sandstone. This happened during the Pleistocene Epoch only one to two million years ago. The cave formation started at least 700,000 years ago, the oldest speleothems are dated 318,000 years.

The rocks surrounding the limestone are metamorphic rocks of Precambrian age, which are about the oldest rocks on earth. But, in contrary to the limestone they are not soluble and thus not karstified. This area is drained by Blackwood River to the south. Rain falling on the limestone surface enters cracks in the limestone and vanishes underground. It forms caves and an aquifer, when the caves get too big they collapse and collapse dolines are formed on the surface. The water flows to the sea and as the limestone continues under the sea it forms submarine sweet water springs. It flows through caves which were formed during the cold ages, when the sea level was lower. The rising sea level caused the flooding of those low passages.

The area around Margate is a rich dairy, cattle and timber region. It is a popular holiday destination noted for swimming, fishing and surfing. The area is renowned for excellent wines.

Cave Road is a tourist route, which winds from Dunsborough to Cape Leeuwin. It connects the caves and karst areas with a total of 500 known karst caves [2022]. Along the route are also seven show caves which have 125,000 visitors per year [2000].

The main problem concerning the caves of the region is the continually declining water table. The results are empty lakes and cave fauna following the water deeper underground. According to the dissertation of Stefan Eberhard (2004) this is a result of a substantial reduction in bush fire frequency (from 2.5 fires/decade to 0.4 fires/decade after 1977) and the cessation of cattle grazing. And he found out that similar events happened before (for a link to his thesis check the literature section for Jewel Cave). When we watch bushfires in Australia on TV we always interpret them as catastrophes. Actually bushfires are a part of the Australian ecosystem for millions of years now. It has become a threat by humans building in fire prone areas and subsequently doing all they can to prevent fires, thus changing the ecosystem massively. A bushfire in 2021 has shown this again, numerous caves were closed for several months, because the structures on the surface, trails to the cave, have been damaged.


1957 National Park established.
2021 bushfire destroyed almost 5,500 ha, several caves closed for refurbishment.
APR-2022 scheduled reopening.