I tried to find some good information about Remarkable Cave online, as the bits of info from brochures and signs is fairly sketchy. Having failed to find much, I read my books. There I found some good info. I'll put this up for now, but I need to read more, get some better pictures, now I know what I'm looking for, and also get inside the cave.
Most of the solid information I have found about Remarkable Cave comes from the work of David Leaman. This comes from his books The Rock Which Makes Tasmania (Review here) and Walk Into History In Southern Tasmania.
The cave was originally called “Remarkable” because of the way there appeared to be a map of Tasmania if you stood inside and looked through the cave at the right angle. You can see this clearly as you stand on the viewing platform.
Now, to make the cave more interesting, it has two entrances from the sea-end. Two separate caves have joined up. I recall walking through the cave many years ago. I think at that time access to the floor of the cave was less restricted. The viewing platform these days tends to discourage venturing further. I didn’t clamber down, as the sea was washing into the cave rear, and there was little point. However, when you can walk through the cave it is very interesting. I’m trying to find photos from all those years ago.
David Leaman’s view is that the cave is quite unremarkable (“run-of-the-mill”). He’s speaking as a geologist. His view is that the intrusion of the dolerite, the rocks it intruded, and the effects that intrusion has, is what makes the area remarkable. I suppose most tourists would disagree, but the rocks are very interesting. They can be seen clearly from a number of vantage points. I think there is also much to be seen inside the cave, so I’m keen to return when the tide is low enough.
In summary, Leaman says the following:
Most of the rocks here are Triassic sandstones. These were intruded by Jurassic dolerite. The intrusion can be seen clearly around Remarkable Cave. The top of the intrusion and its contact with the sandstone can be seen in the cliffs and shore platforms around the area.
The sandstone in contact with the dolerite as it intruded displays “exquisite and intense folding”. The easiest place to see this is from the lookout below the car-park, looking south to the cliff below. Leaman says that if you can walk through the cave, then there is more folding to be inspected. Dolerite of course forms many major nearby features; Mt Brown, Cape Raoul, Cape Pillar etc
The question is whether the folding occurred at the time of the intrusion, or when the rock was laid down. There is no firm answer. A previous doctoral thesis (Powell, 1967 - Studies in the geometry of folding and its mechanical interpretation) had suggested that the folding was caused by the heating of the rock with hot liquids and gasses related to the intrusion. Leaman thinks this is unlikely, and that the sandstones were folded soon after they were deposited, when they were poorly compacted. They were then overlaid by more sandstones, and then later intruded by the dolerite. The dolerite intrusion has altered (metamorphosed) the sandstone by heat. Leaman notes that the distorted sandstones are also intruded and cut by the dolerite suggesting that the folding existed before the intrusion of the dolerite.
Interesting place anyway.
The upper part of the Icehouse Track on Mt Wellington is dominated by the Tasmanian Snow Gums, (Eucalyptus coccifera). There are the burnt remains of solid, thick-trunked trees, some of which have sprouted thinner new branches. In the main they are small and slender trees, and I'm assuming the older trees were destroyed or badly damaged in the 1967 fires, and what we see there now is the extent of the regrowth over the last 41 years. E. coccifera grows to 35m in ideal sheltered sites, but may only be a shrub or stunted tree of 6-9m on the "highest and bleakest sites" (Forest Trees of Tasmania; Forest Resources [Boral Timber] 1995). The trees at the top of the Icehouse Track are obviously the latter.
The leaves are 5-10cm x 1-2cm.
The tips are crimson, and hooked.
The buds are in groups of up to 7 in most sites, but in groups of up to only 3 on Mt Wellington, and up to 1cm x 0.4cm.
The capsules are cup-shaped with a wide flat disc, up to around 1 x 1.2 cm.
These are younger capsules, showing a deep red disc and green cup.
Now, the Snow Gums on Mt Wellington appear to be distinct from those found elsewhere in Tasmania in terms of the maximum number of buds found in a group. On Mt Wellington, there are up to three, and this can be seen in looking at the specimens there. Elsewhere there can be up to seven. At Hartz Mountains, this is the case. These buds and capsules are from trees on the plateau.
Bark of Snow Gum, Hartz Plateau.
