Sawn Rocks at Mt Kaputar National Park in New South Wales are an amazing cathedral like formation, the result of a lava flow from the Nandewar Volcano between 17million and 21 million years ago – I find that time frame hard to get my head around!
The forty (40) metre high cliff face visible at Sawn Rocks is the sheared off remains of a basalt lava flow from the (now extinct) Nandewar Volcano ….The striking columnar fractures are a result of the cooling process: the basalt cools from the outside toward the centre, causing shrinkage cracks to form, commonly, in a hexagonal pattern. The shape of the columns is attributed to tensional stress. When the molten rock within the basalt lava flow cooled slowly and, importantly, evenly, this enabled the individual crystals within the molten rock to align perfectly with each other.
While this type of six-sided (hexagonal) ‘organ piping’ is not rare to lava flows it is exceptionally rare to find them so perfectly formed and preserved and Sawn Rocks is recognised as being one of the best examples of columnar jointing in Australia.
Some of these pillars had fallen to the ground and sheared off to look like perfectly formed paving stones.
Mt Kaputar is the highest peak in New South Wales outside the Great Dividing Range and when I went on a guided tour there we were told that from the top of Mt Kaputar there is nothing to obstruct a view all the way to South Africa. Obviously it needs greater vision than I have but isn’t it interesting to think there is nothing as high or higher for just over 11,000 kilometres.
Two volcanos pushed Mount Kaputar high above the plains, and millions of years of erosion have carved a dramatic landscape of narrow valleys and steep ridges. Many of the mountains are ancient lava terraces. Experience ancient history for yourself by standing on Lindsay Rock Tops – an excellent example of a lava terrace. (Information and photo from http://www.nationalparks.nsw.gov.au)
Now here’s something you won’t find in any old back yard! Mount Kaputar is famous for a very unusual, colourful local – a bright pink slug. It can be seen after rain on rocks, trees and amongst the leaf litter. Not what you’d call your common garden variety of slug.
Sawn Rocks is located 64km out of Bingara on the road to Narrabri. On the way you pass the ancient Rocky Creek Glacial Area. The glaciers that we are more familiar with were formed about one million years ago but this glaciation is very old, dating back some 290 million years to the Carboniferous Period. A vast amount of weathering and erosion occurs in over 200 million years, so all the original glacial landscape features have been eroded away and replaced by those typically associated with running water.
Bingara is a perfect base to explore this wonderful landscape. It was recently named the Free Camp Capitol of Australia and the town values all the different tourists who discover all it has to offer. Can you say “I’ve seen Sawn Rocks”?
March 27, 2018 at 6:45 am
I wish I could.