Monday, May 4, 2009

Swimming the Lava tubes

From Townsville I drove north then crossed the ranges west of Ingham on the Mt Fox - Lava Plains road. Quite an interesting drive, surprisingly dry country and savannah. I made camp at a nice little spot beside the Burdekin River - at this point it was only a fraction of the size of the mighty river it would become. I threw my yabby trap in the water and had enough for a good feed before long. There were areas of what looked like recent lava flows beside the river, and trees here and there had broken up the surface like pavement.

The night was a very cold one and with the combination of the dew-fall on the outside and the condensation inside the tent, I had a surprising amount of drying-off to do in the morning.

My next stop was not far off - Undara. Famous of course for its lava tubes. I'll provide a brief explanation for those not in the know. Quite recently - between about 8 million and 200,000 years ago - the area around Undara underwent quite a lot of volcanic activity as the crust stretched thin. One of the final volcanoes at this time was the Undara volcano, which oozed great quantities of lava. This lava would have followed a river bed and cooled and solidified around the edges and on top, while lava in the centre, insulated, could continue to flow. Eventually as the flow ran out (over 20 years or so), the molten lava would have just flowed out and away, leaving a tunnel. This tunnel is now the 'lava tube' system. Here and there, the tube roof has collapsed, allowing access to a number of separate tunnels.

Undara Lodge and the Savannah guides run tours which are the only way to visit the tubes, which are in a National park without public access. So I took a tour.

The diversity in habitat in the area means there is a good variety of species. The valley where the tube runs is a haven for dry rainforest in a sea of savannah. Rock wallabies enjoy the cool interior of tubes. Tree-snakes and pythons are regularly seen around the entrances when bat maternity colonies form.

One lucky thing about the timing of my visit was that the caves were flooded. This has only happened three times since the seventies. We actually got to swim in the waist-high water down through the black tunnels - a very cool experience.

I saw quite a bit of wildlife while at Undara - there are lots of macropods in the park, and I saw grey kangaroos, euros and antillopine wallaroos, the Mareeba rock wallaby, whiptailed wallabies and bettongs. I spotted a golden tree-snake on the tour too. I did a bit of frogging down at the flooded swamp and some spot-lighting on the rocky bluff, near the Lodge, but didn't turn up anything too exciting, just a pretty young brown treesnake that I regret not photographing.

Golden Treesnake, Dendrelaphis punctulatus

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