Features

Volcanoes

Cape Bridgewater (21km West of Portland) Partially submerged under the sea - caldera volcano around 3 million years old.

Mount Richmond (24km NW of Portland) submerged under sand dunes made of tuff not basalt. Formed around 2 million years ago.

Mount Rouse (34km NW of Hamilton) around 1.8 million years old. 120m above surrounding landscape (360m above sea level). Composite volcano of scoria and basalt. Major Mitchell named it in 1836.

Mount Eccles (9km West of Macathur) Fissure volcano around 30,000 years old and has scoria cone, lava tunnel and crater lake. Major Mitchell named it Mt Eeles in 1836.

Tower Hill (14km West of Warnnambool) Volcanic complex, caldera, nested maar, scoria cones and tuff ring aound 23,000 years old. 110m above sea level on NE side.

Mount Napier (17km South of Hamilton) Composite volcano with large lava flow 8,000 years old. 150m above plains.

Features

Lava canal

What is a lava canal?

Lava canal is a canal filled with lava, not water. Sometimes the canal overflows or a crust may form over the top but the lava beneath is still flowing. Over time the lava levels drop and hollows or tunnels may form. In rare instances the tunnels remain intact as in the Mount Eccles lava tunnel.

Where ?

Mount Eccles lava canal (9km West of Macathur or 45km SW of Hamilton). The lava tunnel was thought to be formed some 30,000 years ago with the eruption of Mount Eccles. The tunnel may be entered via steps (Bring a torch). The tunnels in the canals are up to 60m long.

Features

Lava Caves

How are lava caves formed?

Lava caves can be the result of lava canals. The top layer of the lava cools but molten lava still flow beneath in tunnels. When the lava drains away hollows are left. Sometimes the lava crust on top is too thin and collapses to reveal the caves. Evidence of a lava cave are lava dribbles, stalagmites and stalactites.

Where?

Byaduk Caves (located 25km South of Hamilton) were the result of the Mt Napier volcano (Harmans Valley lava flow which is 24km long). The Byaduk Caves are within the Mount Napier State Park and thought to be around 8000 years old.

The caves are accessible by paths and are able to be entered (recommended for experienced climbers only). Some of the tunnels are 18m wide and 10m high also reaching depths of 20m.

Features

Tumuli or Lava Blisters

What are tumuli or lava blisters?

Tumuli, otherwise known as lava blisters are a unique feature of South West Victoria's landscape - the result of the Mt Napier Lava flow (Harmans Valley flow). The tumuli are also thought to be around 8,000 years old. Tumuli are domelike steep sided stone rises - some are 10m in height. Gases in the lava accumulate to produce bubble like structures which grow higher that of the lava flow.

The skin forms a crust and the blister hardens to form the dome like structures. Some of the domes have their tops collapse but the sides remain intact. Blisters erupting from cracks in the lava are also features of this area.

Many of these blisters remain and can be viewed from the road. (Please note as the lava blisters are on private property please do not enter the property.)

Features

Waterfalls

What is the connection between waterfalls and volcanoes?

Various waterfalls in South West Victoria were formed because of various lava flows. When lava erupts from a volcano it usually follows the river valleys or streams or low lying areas. Rivers or streams sometimes cut their way through or flow along the sides of previous lava flows to form waterfalls.

Where?

Wannon Falls (17km West of Hamilton) was formed by an ancient lava flow which surged upstream. Today what remains is a 30m waterfall (when rainfall is good). Also noticable in the valley are the basalt rocks which were once the waterfall which has retreated upstream.

Nigretta Falls (11km NW of Hamilton) also the result of ancient lava flows. Access to the waterfall is provided via several paths. When the flow is minimal the evidence of the lava flow is obvious.

Hopkins Falls (12km NE of Warnnambool) Another waterfall the result of lava flows from over 1 million years ago. Softer layers have eroded to leave the harder basal layers. Hopkins Falls is one of the widest in Australia 90m wide and 11m high.

Features

Caldera

What is a caldera?

Calderas in the general sense are volcanoes where the cone has collapsed on itself as a result of its own shear weight or the subsidence of the volcanoes base. Sometimes the collapse of the cone may leave a shallow lake.

Where ?

Tower Hill is located 14km West of Warnnambool. Tower Hill is a complex volcano. The history of its activity has seen many stages. One of the stages that make it a volcanic complex Volanic Complex
Refers to the various stages a volcano may go through. They may start off as shield volcanoes and with successive eruptions may produce a cone with layers of lava and ash. The volcano would also be a composite volcano. is the evidence of subsidence such as in caldera collapse. Tower Hill is also renowned as being one of the largest maars in the world and has geological significance.

Cape Bridgewater located 21km west of Portland. It is a paritally submerged caldera volcano formed over 3 million years ago. Blowholes and a petrified forest are also evident at Cape Bridgewater.

Facts

Tower Hill Game Reserve is a dormant volcano. It is also referred to as a nested maarNested Maar
Where further volcanic activity within a Maar volcano produce more inner cones. as it has had further eruptions of scoria in its crater. There are 10 scoria cones in the Tower Hill crater. Tower Hill was declared Victoria's first National Park in 1892.