Saturday, 3 December 2011

Looking out from the lookout at Point Lookout

The view of the National Park from Point Lookout
One of my favourite places is Point Lookout at the New England National Park between Ebor and Dorrigo. Point Lookout is spectacular for it scenery and feel. On most days you can see the pacific ocean while looking over rugged hills and valleys and I particularly like going there during winter where icicles hang from trees and the waterfalls below the peak are frozen. Point Lookout is nearly 1560metres high which I understand makes it the highest point in northern New South Wales. Like the beauty of the Mount Warning area and Tweed and Brunswick River region, Point lookout owes its attractiveness to the erosion of a large shield volcano.

Point lookout is located on the rim of an escarpment which formed through the erosion of the Cenozoic aged (in this case 19-18 million years) Ebor Volcano and the much older Devonian to Carboniferous (up to ~416Ma) accretionary complex rocks that make up the balance of the New England tablelands. Today, only the north western portions of the lavas (called the Ebor Volcanics) and the central weathered volcanic plug from the Ebor Volcano remain. Research by Ollier (1982) suggested that the central volcanic plug of Ebor Volcano was centred on what is called the crescent which is actually a fairly insignificant looking feature when compared with the rugged valleys today.

It is interesting to note that even though the nearby 23 Million year old Mount Warning (located near and over the Queensland border) is regarded as one of the biggest shield volcanoes in the southern hemisphere, having a height of around 2000 metres before it was eroded, the Ebor volcano was probably a similar size or bigger at its greatest too. It is a bit of a mystery why so little is left of Ebor Volcano when so much remains of the Tweed Volcano/Mount Warning.

The Crescent complex once thought to be Permian (290Ma-250Ma) as recently at the 1970's and was considered part of the intrusives that constitute the New England Batholith. In fact most of the most 'current' geological maps of the area were drawn at this time and so they are incorrect. But since investigations on the radial drainage patterns and geological features by Ollier in the late 1980s followed by dating by Gleadow and Ollier (1987) (which is difficult due to how weathered the Crescent is) and more recent work by Ashley et al (1995) now it is known to be the centre of the Ebor Volcano and aged around 19 Million Years. Ashley et al (1995) also discovered that a nearby basalt called the Doughboy Basalt was around 46 Million years old which is clearly not related to the Ebor volcano but is consistent with other locations where an older Cenozoic basalt is present before the hot spot volcanism that formed the Ebor, Mount Warning and other volcanoes existed.

When I was last at Point Lookout there were several bush walks from long and difficult to short and easy. The most difficult ones take you into the valleys where the rock has been eroded into the older accretionary complex. But even on the short one you can see some interesting 'recent' volcanic rocks. On a section of the walk around the top of the cliffs where security fences are necessary (lest you plummet away!) there is cuttings through the rock. In this rock look closely and you'll see some big crystals within a fine groundmass. This rock is a type of basalt called tholeiite (which means that it has crystalised with a certain geochemical signature) and the crystals are feldspars which is a common rock forming mineral. The feldspars here quite obvious and seem to catch the light at two angles, this feature is called twinning and is characteristic of the calcium rich variety of feldspar called plagioclase. Along the bigger walks below the point dacite can be found as well as basaltic and dacitic breccias at the stunningly beautiful during winter, weeping rock and numerous palaeosols.

The remnant of the shield volcano shows the characteristic radial drainage pattern for volcanic shields but the eroded central areas of the volcano (including the caldera if there was one) drains fairly directly to the east via the Nambucca River. The radially draining creeks and rivers are well known for their waterfalls such as Dangar Falls and Ebor Falls.

The road from Dorrigo to Armidale is not a busy route, it is often missed by many people but I always recommend people visit the New England tablelands because of its beauty and uniqueness in Australia. Point lookout is just off the Waterfall Way which name probably gives you an indication of many of the other attractions. In my opinion, the depths of winter are the best times to visit to get the mood and subtle beauty of the area. I should get back there myself... it has been too long since I was last there.

You may be interested in a self-guided geological tour. Bob and Nancy from Armidale have a wonderful site which includes an excellent (and expanding) range of geological tours including ones of the Northern Rivers Area. Their tour guide on Point Lookout can be accessed from their webpage (very much worth the look) or  directly linked from here.   

References/bibliography:

*Ashley, P.M., Duncan, R.A. & Freebrey, C.A. 1995 Ebor Volcano and the Crescent Complex, northeastern New South Wales: age and geological development. Australian Journal of Earth Sciences V42.
*Gleadow, A.J.W. & Ollier C.D. 1987 The age of gabbro at the Crescent, New South Wales. Australian Journal of Earth Sciences V34.
*Ollier, C.D. 1982 Geomorphology and tectonics of the Dorrigo Plateau, NSW. Australian Journal of Earth Sciences V29.

10 comments:

  1. Always wanted to know more about the Ebor Volcano and you answer some of my questions. Thanks Rod.
    Agree that the Waterfall Way is a great place to visit. Ebor Falls is one of my favourite spots. There is (hope this is right) some incredible basalt columns on the lower falls.

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  2. The Guy-Fawkes River runs mainly through older accretionary complex rocks (metamorphosed ocean formed greywakes) a very short distance downstream of the falls but the falls themselves pretty much mark the edge of the Basalt I think. There are some lovely big columns of basalt at the falls!

    Ebor always had a lovely little cafe that I hope is still there and a pub for a good lunch. Thanks for the encouragement Mark.

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  3. Interesting post, Rod. I love the drive along Waterfall Way, which we did last year. Next time, I hope it's not raining!
    We have a photo of Ebor Falls on our wall - lovely place that we would like to visit. We hope the cafe and pub are still there the next time we pass that way.

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  4. Hi wangiwriter,
    What a shame about the weather! The upper Ebor falls are very close to the road though... even if it is raining it is worth a quick run to the lookout! Hope you get the chance to travel that way again soon and hope to talk to you again soon too.

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  5. Great post Rod.

    Not only is it interesting for geology, but there are some superb examples of differing vegetation types from alpine snow forests, amazing cathedral-like beech forests and very rare heath lands. All within an hours walk. Great spot, and I think you can even hire cabins up there for the night.

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  6. Rod

    You and your readers might be interested in a discovery made around Ebor and Guyra just last week, when I was working with a team of glacial buffs from UQ and UT. We found definite evidence of periglacial activity, presumably from the Last Glacial Maximum, ~20 000 years ago. The best examples were at Guyra on the slopes around Malpas Dam--clear evidence of solufluction lobes, rock glaciers, snow hollows, and other freeze-thaw features, and what could only be described as incipient cirques--ponds and bogs sapping back into the escarpment and probably still holding some snow in the frigid Guyra winters. The curious point is that they were between 1200 and 1300 metres, not at the highest points above 1500 m where we were expecting them, but all on steep south facing escarpments.

    One intriguing feature near Point Lookout, on the road up where it crosses the Little Styx River and at 1450m, was what looked very like a terminal moraine. This of course is a glacial, not a periglacial feature, so it is very hard to believe--but have a look at it, and see what you can make of it. There were at least 16 glacial cycles in the Pleistocene, so maybe one of them at least was really severe, and glaciated this far north. Otherwise, you have to go back to the Permian...


    Bob H.

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  7. Hi Bob,

    Quite intriguing! I wish I could spend more time up that way. I know the landscape around Malpas dam but not the geology. I did not even think about glacial related landscapes in the area... probably because evidence of glaciation is fairly rare in Australia (comparatively). Next time I'm in the Ebor area I'll check out that moraine... Wow... I hope it is (and I'm not confident in my ability to confirm it) but that would be a rare find here!

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  8. Bob, very interested to see if I can find the feature you mention on google maps.
    I assume the little styx river crossing on point lookout road is this one?:
    https://www.google.com.au/maps/@-30.507853,152.36694,3a,75y,100.29h,86.17t/data=!3m4!1e1!3m2!1sexvjqIlfA_CHPnk7HI03pQ!2e0

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  9. Hi there Rod,
    This blog is a few years old now but I hope it finds you.
    My late father was very interested in the Ebor Volcano and did a lot of looking around the whole area. He has written down some theories and conclusions that as yet has not been seen by persons of your educated levels. He was a farmer in the Nambucca valley at Missabotti. I would like to be able to share this info with you if you are interested. I am also in possession of some VERY unique rocks that were found in a pre EV riverbed running north to south across the valleys of the Nambucca and Macleay tributary's that I would dearly love to find out their origin.
    Frazer Gorely,
    Wauchope

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    Replies
    1. Hi Frazer,

      I've obviously been off the blog for a few weeks/months. Sorry it has taken so long to reply.

      Yes, I'd be quite interested in what you know about Ebor Volc. My email address can be found by clicking on the "About This Blog" tab on the top of the page. I'd please feel free to email me,

      Cheers,

      Rod.

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