The Harman Valley lava flows from Mt Napier 8000 years ago were able to travel long distances without spreading sideways. The flows cooled at the surface to form a crust while the lava inside continued to flow. Eventually, the internal lava drained away leaving hollow lava tubes or tunnels. Weathering and erosion caused the ceilings to collapse here exposing the tunnels and caves below. Some of these caves are open for up to 250m. Mammal bones, including those of the Tasmanian Tiger, have been found in these caves, which are also home to the bent-winged bat. To avoid winter food shortages the bats slow their body systems down in what is known as torpor where their body temperature matches that of their surroundings. Disturbance during this period can kill them. Only one cave, Harmans 1, is open to the public, but you will need appropriate footwear, clothing and a torch. However, the caves are closed during the bats’ torpor period.
This is the sixth in our Vulcan series of caches along the Volcanoes Discovery Trail, which we learned about while doing Derringer’s “What a Blast” cache. Brochures on the Trail can be obtained at the Colac, Hamilton, Port Fairy, Portland, Warrnambool, Tower Hill or Penshurst Visitor Information Centres in Victoria, and Millicent or Mt Gambier in South Australia.
Other maccamob caches on the Trail are:
Ready To Rock
A Leurid View
Big Rock Candy Mountain
What A Blast (Derringer), Elemental Forces (Derringer), Centenary (Team Piggy) and Towering Inferno (Alex) are also on the Trail.
Take time to enjoy the interpretive displays at each cave site. Because of the deep holes, you will need to be careful with geochildren here.
Please try not to disturb the area too much in your searching. You only need to lift one rock to reveal the cache, and if you are observant, you can catch a glimpse of it beforehand. Please replace that single rock (and don't add any others) before you leave so that the cache is hidden from casual observation again. Please also replace any other rocks you might disturb exactly as you found them (with any lichen uppermost).
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