Thursday, September 24, 2015

Thursday, Sep 24th, Quorn, Australia


At the suggestion of local friends, we drove north from Adelaide to Quorn.  It's about as classic a small town as you can get, with a street plan spanning 48 city blocks.  The name was given to it by Governor William Francis Drummond Jervois in 1878, whose private secretary was from the Parish of Quorndon, England.  Today, we had breakfast at a local cafe (Emily's), and we're back after a long day driving up in the Flinders Range - to upload photos through their wifi.

A few minutes later, twenty horses came down the street with riders.  Sally Brown, the owner (her sister is Emily), commented that it was a group who had come to town for a meeting. There are tourists in town, as we've seen in the two hotels where we ha dinner.  But this isn't a town where tour busses stop.  It's one of the last places to stay in a hotel before the Flinders National Park, and is a good day's drive from Adelaide if you stop frequently to look at flowers.

Flinders National Park used to be an ocean seabed.  And like a lot of national parks, it's mountains are composed of sandstone and limestone from the elements found a long time ago (500-600 million years) in the sea.   But the mountains seem unusually wave-like in design, like ripples across the landscape.

Here's what the official explanation is: The Flinders Ranges are largely composed of folded and faulted sediments of the Adelaide Geosyncline. This very thick sequence of sediments were deposited in a large basin during the Neoproterozoic on the passive margin of the ancient continent of Gondwana. During the Cambrian, about 540 million years ago, the area underwent the Delamerian orogeny where the geosynclinal sequence was folded and faulted into a large mountain range. Since this time the area has undergone erosion resulting in the relatively low ranges today.
Most of the high ground and ridgetops in the Flinders are sequences of quartzites that outcrop along strike. The high walls of Wilpena Pound are formed by the outcropping beds of the eponymous Pound Quartzite in a synclinal structure. The same formation forms many of the other high parts of the Flinders, including the high plateau of the Gammon Ranges and the Heysen Range. Cuesta forms are also very common in the Flinders.
The Ranges are particularly renowned for the Ediacara Hills, South-west of Leigh Creek. This was the site of discovery in 1946 of some of the oldest fossil evidence of animal life. Since then similar fossils have been found in many other parts of the ranges, though their locations are a closely kept secret due to the risk of sites being desecrated. In 2004 a new geological period, the Ediacaran Period was formed to mark the appearance of Ediacara biota.
That one feature described above (Wilpena Pound) which looks from the air like a collapsed volcano, is a natural amphitheater called a syncline, a folded sedimentary rock laying on its side.

It looks like this from space.  It's the main entrance at Wilpena, and the visitor center and bus ride up to near the top is great.  We. however, were going to drive for five more hours and had to get back to Quorn before the kangaroos came out - so we passed on climbing up to look into the actual amphitheater.

Further along the park road, we got to see some of the rich geology of the Flinders Ranges.  Pat and I love wild rides on roads where we really ought to have taken a big powerful jeep, and the upper section of this park contains some of those roads.   Click on Flinders Ranges to learn more about this fascinating region.

We'll head south tomorrow to Murray River, Australia's longest river, on our way to the Great South Highway.

Here are links to recent photos (not as many on long drives):
Wednesday, Sep 23rd, Quorn
Thursday, Sep 24th, Quorn

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