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Ancient Skies, Ancient Climbs

Community Highlights Oceania Ancient Skies, Ancient Climbs

We arrived yesterday to the regional centre of Narrabri, a major cotton growing area of Australia. Before the arrival of the Europeans in the early 19th century, Narrabri was the home of the Kamilaroi people, who still constitute a significant part of the local population. Narrabri derives its name from an early property in the district called the Narrabry Run. The name Narrabri is aboriginal in origin and has several possible meanings which include 'snake place', 'big creek' or 'Forked Sticks'.

Today was a hot one, and we learned from one of the National Park workers that the cause of a haze across the plains was due to most likely a fire plus a dust storm from the western desert plains. It gave the sky a very milky colour instead of the deep blue we normally have been seeing.

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First we headed over to the CSIRO Australia Telescope Compact Array at the Paul Wild Observatory over to the west of Narrabri at a township called Wee Waa. It's a huge facility that cost about $50m to build a few decades ago which consists of an array of six 22m antennas used for radio astronomy that work together using a technique called radio interferometry. It is the largest and premier instrument of its kind in the southern hemisphere, which is important as Australia itself has a unique vantage point on observing our own galaxy compared to the northern hemisphere. It operates 24/7, 356 days a year and is only for astronomy. The radio waves being tracked and studied allow not just Australia but other counties to study cold hydrogen gas clouds, energetic electrons spinning around massive black holes (and finding multiple micro-black holes in our own galaxy), pulsars and even the glow left behind after the big bang. It's amazing science. We were able to read and understand the components that make up the sophisticated measuring and scans of radio signals, and then we used one smaller antenna to aim at the sun as well as ourselves to find and check the frequencies emitted.

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You can check out the array here to see exactly what it's looking at and the configuration of the six antenna.

We then said goodbye to the high powered science and headed southwest to Yarrie Lake. Now this perfectly circular body of water is 3km in diameter around the rim but with only a floor of 2m deep in the centre. A few million years ago, a meteor fell and crashed here. With erosion from wind and the tendency of this floodplain to be flash filled, the walls have smoothed away leaving only a remnant of the impact site. While most of the waters near this area are crystal clear, only in Yarrie Lake is it with a very unusual milky colour which is said to come from the bases of the creeks and soil around the scrub nearby. With the sky still hazed from smoke and dust, the water and skyline were nearly the same colour! Tom and Alexis played a bit in the shallow water along the rim and shoreline before we packed up and headed on.

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Our next stop was the Mount Kaputar National Park, where some of the most ancient rocks and formations are in Australia and indeed the world! The magnificent Sawn Rocks is where we went first and are one of Australia’s best examples of a rock formation called ‘organ-piping’ – because they look like a wall of giant organ pipes. They are a fascinating reminder of Mount Kaputar’s volcanic past. The kids enjoyed walking and climbing on some of the lesser (although still two stories high) clumps that have broken off the main surface while I climbed up to the side of the cliff face. The organ-pipe effect is created when a lava flow cools slowly and evenly so the forming crystals align perfectly, with the uniform shrinkage causing cracks that join up to form the columns. Unsurprisingly it's also known as columnar jointing! I thought it was amazing, these natural features looked as though they were crafted by hand, and even the ground at the base had evidence of the features. In the shadow of the impressive 1510m Mt Kaputar – that rises 1510 metres and is what's left of the Nandewar Shield Volcano that ruptured into virtual oblivion back in the dim distant past.

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From there we went over the mountain and down near a rural spot called Bingara. Again, we went back in time about 300 million years ago and were standing at the base of a huge ancient glacier that cut through the granite, volcanic and sedimentary rocks. We saw the typical glacial features where there were angular pebbles and boulders, lots of sand and finely ground rock and there was a lot of angular and oddly shaped rocks many with flat faces and very sharp edges, all showing sighs of plucking from the walls of a glacier by the slow yet steady ice movement. There was varved siltstones present which Sophie and I were interested in, showing the seasonal deposits of silt and mud from the glacial met water. There were a huge amount of drop stone pebbles and boulders that showed up they were transported in fragments of glacial ice and released once the ice began melting, sending these huge things down to the bottom of a great lake where they were embedded in the silt. Now it looks as though the rocks are made from concrete with thousands of different sized rocks and pebbles of different colours trapped.

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After such a long day walking and exploring ancient Australia, we couldn't help ourselves but take a break and dip our feet in the creek!

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This featured blog entry was written by giffords from the blog Ridgey Didge Spring Vacation.
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By giffords

Posted Tue, Sep 24, 2013 | Australia | Comments