Riversleigh

After I’d been to the underground hospital museum with the three buildings, I booked the last session of the day for the Riversleigh experience at Outback at Isa. Riversleigh is a very large fossil site in the Gulf of Carpentaria region. It’s a UNESCO World Heritage Site (along with the Narracorte Caves in South Australia) and a Lagerstatten (the most scientifically significant fossil sites - our others are The Age of Fishes at Canowindra and the Edicarian Fossils at Nilpena in South Australia). The limestone rocks at Riversleigh contain bones which are some of the most recent fossils you can find - 15 million to 25 million years old, showing what the ancestors of our Australian fauna were like. They dissolve the lime from the rock, and are left with bones, ranging in size from the bones of megafauna down to what look to be grains of sand. However, when you put these grains under a microscope you see microscopic bones of really small creatures. Outback at Isa has the tanks dissolving the rocks and does the work to identify the bones.

It was a pretty amazing experience! I had already decided to extend my day today to visit Riversleigh itself on my way to Camooweal. It extended my driving to over six hours, rather than the two and a half hour trip I would have had between Mount Isa and Camooweal, but I thought it would be worth it. The site is mainly fenced off but there’s a section that’s open to the public with paths and rocks and lots of explanations. It’s a very remote area, so there aren’t any rangers at the site or the national park next door, and a lot of the road is dirt. Having had the Outback in Isa experience, I felt that I would recognise the fossil rocks when I saw them.

The road from Mount Isa to Camooweal starts with some of the same glorious scenery that I’d enjoyed going from Cloncurry to Mount Isa, but it soon changed into flat Mitchell grasslands. There was a road stop with information about the Landsborough Highway. It was named after an explorer who had been sent to find Burke and Wills, and had mapped this part of the world. In WWII, they needed to be able to send convoys from Mount Isa and Cloncurry to Darwin, so they built the Camooweal to Mount Isa road. Up to 1000 trucks a day used the road during the war and it has been the main road linking Darwin to the eastern states ever since.

I found the road to Riversleigh. The first part was paved, and after the dirt road started, there were some significant sections of paved surface, but it was mainly a very dusty road. Every caravan going in the opposite direction sent up a big plume of dust, and I needed to stop each time before I could see to continue. It was mainly scenery like around Mount Isa with occasional sections of Mitchell grassland. Then there were a couple of creek crossings which had been concreted and the water was so clear I could see the bottom easily. Then I came around a corner, and there were five vehicles at another crossing. The water was flowing fairly fast and it was deeper than the others. I think it must have gone up overnight because another vehicle was on the other side, and the driver was very hesitant about crossing it. The road goes nowhere, so they must have crossed it previously.

It turned out that three cars with trailers and caravans were a convoy going to the national park campground. There was also a vehicle that looked like a VW combi van. They were international tourists, and had tried to cross but had wet their engine so they were stuck. The convoy had set up starlink so they could talk to their son in Brisbane to get out of their situation, and everyone was waiting for them to finish before they could proceed. I decided to go back since I haven’t crossed this type of crossing. I knew I was only a couple of kilometres from Riversleigh at the most, so it was disappointing. I figured out afterwards that Riversleigh was less than a kilometre away, so I could have walked across the creek and visited Riversleigh and come back. I offered to take the foreigners to Camooweal, but they declined.

I was following a truck for the first part of the way back, and the dust was dreadful even though I tried to stay well back, but I overtook it on a section of paved road, and got to Camooweal by just after 3pm.