16-22 deg C
Death by Undara today. We were booked on the 10:30am tour (takes about two hours) and had to meet at 10:20am for a brief about our day, and were on the bus by 10:30am; better than being in the military. Our tour today was the ‘Archway Explorer’ which was the same as the ‘Active Explorer’ except we had stairs and walkways instead of having to clamber over rocks. Whilst we were being driven to the Tubes we were given a running commentary about the bush, wildlife and the different types of rocks found here – basalt and granite.
For millions of years Undara was an active shield volcano. About 190,000 years ago there was a massive eruption and lava flowed more than 90 km to the north and over 160 km to the north-west. An estimated 23.3 km3 of lava flowed from the volcano at a rate of about 1000 m3 every second. A lava flow this large could fill Sydney Harbour in six days. It is thought that the lava flowed at a temperature of around 1200 °C. The lava tubes and caves were formed when rivers of lava confined to a valley crusted over and formed a roof. Insulated in its casing of solidified lava, the lava flow carried on for tens of kilometres before draining out, leaving an empty tube of lava. Weaker sections of the roof of the tubes later collapsed to form caves and depressions. More than 50 caves have been found in the park. The Undara lava tube system is Australia's longest, and one of the longest in the world. It is also unusual, if not unique, in that it developed on a granitic basement.
The tour started with the Archway which was once part of a very large tube, but over time the roof has collapsed leaving just the archway. Next stop was at Ewamian Cave and lastly Stephenson Cave. To get to the caves you had to walk along the inside of a tube.
After lunch and a short nap, we cycled out to the Kalkani Crater to walk around the rim as we had been told it was quite spectacular. We were also told the road was in very good condition; it may very well have been if you were in a vehicle, but on a bike, it was quite torturous – corrugation after corrugation! Anyway, we eventually got there and climbed up to the top of the rim only to find we couldn’t really see the crater due to the mass of vegetation. So, after a while we decided to turn back. On the way home, Wendy got caught in a really rough patch or corrugations and came off the bike again! Not too much damage done, just a bit of skin missing.
After
dinner, it was not long before we were in bed sleeping like logs!
