The Volcanic Discovery Trail
Mt Eccles, Mt Napier, Mt Rouse, Byaduk Caves and the Lava Tumuli (blisters) are all part of the Volcanoes Discovery Trail encompassing western Victoria and south-east South Australia.
Volcanic eruptions began in this area approximately 20,000 years ago and continued until approximately 8,000 years ago. These volcanic plains rank as Australias most extensive volcanic province. In global terms, it is included within the top six most significant volcanic provinces.
Mt Eccles
Situated 45km (1/2 hour) south of Hamilton, Mt Eccles is surrounded by 6120 hectares of national park and boasts Victorias highest koala population and largest Manna Gum woodland koalas favourite food! . Three main craters at Mt Eccles holds the waters of Lake Surprise, a body of water around 800 metres long and 300 metres deep.
The Tyrendarra lava flow is the youngest flow continuing from Mount Eccles, extending over 50 kilometres to the west and south. Along this flow, many well preserved features are present including stony rises, lava caves, channels and a subsidiary spatter cone known locally as the shaft which opens to a depth of 30 metres. The park has well developed walking trails for visitors to enjoy the beautiful flora and fauna, fascinating volcanic formations and interesting lava caves. It also features picnic spots and camping facilities.
Mt Napier
Approximately 20km south of Hamilton lies Mt Napier, the youngest volcano in Victoria and the highest volcanic point in the Western District Plains. Surrounded by Mt Napier State Park, Mt Napier has many eruption and lava flow features that are remnants from the last stages of volcanic activity believed to have occurred less than 10,000 years ago.
Of particular note is a major late eruption of fluid basaltic lava, considered to be one of the earliest lava flows dated on the continent, which provides the source of a flow that extends for over 24 kilometres along the valley of Harmans Creek. A variety of features have been well preserved for viewing, with some lava flows reaching as far as the sea between Port Fairy and Portland.
Australia's youngest volcano, Mount Napier, overlooks the remains of the river of lava that it lay less than ten thousand years ago.
Byaduk Caves
Mt Napier State Park also takes in the Byaduk Caves, considered to be the most extensive and accessible sets of lava caves in Australia. The caves were formed when lava flowing from the volcanic crater was quickly cooled by outside air, forming a crust with hot liquid lava flowing beneath.
When the lava flow ceased, a hollow tube was left behind. The caves are accessed through collapsed roof sections and display many well preserved features left by the retreating and cooling lava including lava tide marks on cave walls, lava stalactites and various joint and flow layering structures. The largest caves are 18 metres wide, 10 metres high and extend 20 metres below the surface. Walking tracks follow cave edges and have a number of viewing points to observe flora, fauna and lava features.
Lava Tumuli or Blisters
West of the Byaduk caves, near the limits of the Harmans Valley flow are a number of unusual clusters known as Lava Tumuli or Blisters. Lava Tumuli are clusters of unusual circular mounds or hummocks of rock, up to 10 metres high and 20 metres in diameter, caused by the lava flow. These blisters are considered to be unique in Australia and most likely rare on a world scale.
The lava tumuli can be seen along the edge of the Harmans Valley flow at Wallacedale, 13 kilometres west of the Byuduk Caves.
Mt Rouse
Twenty minutes east of Hamilton, lies the town of Penshurst, home to the extinct volcano Mt Rouse. The mountain is a massive accumulation of scoria, rising 100 metres above the surrounding volcanic plain.
To the south of the main scoria cone is a deep circular crater with a small lake and shallow crater rimmed with basalt. Past lava flows from Mt Rouse followed shallow, gently sloping river courses, extending at least 60 kilometres south. A thin basalt lava flow contained in the scoria cone has been dated approximately 1.8 million years old. The Mt Rouse summit provides panoramic views of the lava plain and surrounding district.
For further information on visiting the Volcanic Discovery Trail, contact the Hamilton Visitor Information Centre
by: Southern Grampians S.C.