The eruption. The Mt Eccles volcanic erruption is now dated at more than 30,000 years. The lava flowed along channels and travelled as far as the sea. It flowed past Port Fairy and 15km beyond the present shoreline. At his time the sea level was much lower than today.
Lake Condah is one of the wetlands created by this volcano. The stones were used by the local Gunditjmara people to construct channels and weirs to aid fishing.
As the eruption progressed the fissure sealed and the action was confined to a series of vents which formed along it. The lava flowed from these vents along the channels and through tunnels.
Lake Surprise. Most were suprised to see Lake Surprise through the trees. Lake Surprise is in the centre of the crater, and is a water-table lake.
Tunnel Cave. We walked into the Tunnel Cave. The lava tube is like a long cave, extending 60 metres into a hill. This was an old side flow, where molten lava crusted over at the top. The lava continued flowing beneath, and flowed out the other end, leaving a hollow tube. There are numerous features to be seen: including ripples and flowlines. The life-forms alter with distance from the mouth: plants with chlorophyl near the entrance, to lichens to fungi.
The lava canal. We walked along the main lava canal for over 3 km. It was a deep, rock based depression with quite high sides. Often there were man-made stone walls on the top of the sides. Thse were used as fences for stock. The area is well vegetated with trees, shrubs and mosses. Many of the rocks have lichen. Koalas are plentiful.
We lunched at Smoko Cave, then climbed up the canal wall to return along the high ground.
The Natural Bridge was an impressive feature with access by steep steps at either end. Viewed from the centre of the cave, the entrance had a triangular cross-section. The roof (the natural bridge) was formed by an overflow of lava. The lava, as it cooled, built up thick layers to form a levee. These grew inwards and arched over to join and make a roof.
On our return to the car park we passed dry craters. The base of these are above the water table and so are dry. There were wonderful views from the summit of Mt Eccles. We could see the ocean, Portland, windfarms and Lady Julia Percy island.
Other highlights included:
Contributed: several sources
1. Lake Surprise with Manna Gums. The water is at the level of the water table.
2. Canal. During the eruption, a river of molten lava flowed along this channel. The canal has steep walls. The stone fence was built to hold stock. Trees and shrubs include Manna Gum, Blackwood and Bursaria.