Archives for October 2019

Introduction

The identity of the Volcanic Seven Summits is well-known (see here). Of these, there is currently a recognition of Mount Giluwe as the highest volcano in Australasia.  However for those who consider Australia (rather than Australasia) as the true continent, identification of the highest volcano in Australia may be of import.  It could also affect people’s views of the volcanoes that are to be regarded as members of the Volcanic Seven Summits. A sort of Carstensz versus Kosciuszko argument as to which should be recognised as the seventh volcanic summit. 

Determining which volcano is the highest in Australia has proven difficult to ascertain. This note does not come to a definitive conclusion. However, on balance I think that the answer is likely to be Brumlow Top in the Barrington Tops National Park of New South Wales. In coming to this view I have ignored Mawson Peak on Heard Island which is 2745m high. Whilst Heard Island is an Australian external territory, it is clearly not a part of the landmass of Australia itself.

[Since I originally wrote this blog, further survey work has been undertaken of certain of the Australian mountains. This has given Round Mountain the same height as Brumlow Top. I do not think that this changes the conclusions of this blog. However, those who are interested in climbing the highest might want to climb both!]

Mount Bogong

Readers will note that there is no mention of Mount Bogong.  The Wikipedia page dealing with Australian volcanoes suggests that Mount Bogong is the highest volcano.  However, there is at the time of writing this blog a comment in the Wikipedia entry suggesting that Mount Bogong’s entry is in error. “Mount Bogong is composed of metamorphic sedimentary rocks” it says.  Indeed the coordinates given in Wikipedia for the location of the volcano lie 80km to the south of Mount Bogong.  This is the location of the Bogong lava field.  Mount Bogong does have volcanic rocks. However these have been uplifted in much the same way as those on Aconcagua (which was for a time also once thought to be an extinct volcano).  So the evidence suggests that we can probably discount Mount Bogong.

What is a volcano?

This brings me to the question of what is a volcano?  For this purpose I have discounted locations where volcanic activity has led merely to extrusions of lava at the Earth’s surface.  I have also taken the view that to count as a continental (or country) high point for this purpose, there ought (if possible) to be a suitable prominence from its nearest highest neighbour. 

In terms of the first condition (mere extrusions of lava) this makes no practical difference here.  There are no such locations in Australia where this would determine which point is the highest volcano.

As for the second condition (prominence), I consider that 600m would be the right measure.  Of course one can argue over the use of this number.  It is only an opinion after all.  But if one is talking about a volcanic mountain, then a suitable degree of prominence is (in my view) apt.  In fact, in this case, the point only matters if one thinks that a prominence of less than 100m could define a volcanic mountain.

An equally interesting question is whether something that once was a volcano could subsequently cease to be one.  This is not an issue with any of the currently recognised Volcanic Seven Summits.  But, Australia is an ancient landmass.  What happens where a mountain that once would have been categorised as a volcano is so eroded over time that it is reduced back to roughly its original landform, but now with a vent running up through it?  This is the situation with one of the candidates listed below.

The table below identifies suitable candidates.  Australia is not, I suspect, normally identified as a location of volcanic activity – at least by the lay person.  But, as an ancient landmass, it has experienced significant amounts of volcanic activity over the millennia, particularly down the east coast.  Being an ancient landmass, time has considerably eroded the volcanic formations.  The volcanic activity has been in the form of shield volcanoes (rather than the more noticeable and readily identifiable stratovolcanoes) and lava fields (where lava exudes through faults in the Earth’s surface). 

The highest volcano in Australia

Although my conclusion is that one should consider Brumlow Top to be the highest volcano, I am most certainly not an expert in volcanology (or geology).  Quite the opposite.  I have read a few articles on the internet by apparent experts.  Many refer to scientific papers that are available only on payment which might shed more light on the matter.  I have not sought to access those papers.  So the conclusions in this note are up for debate.

If I am right, a more worthy winner would have been Mount Kaputar.  It stands supremely isolated and does not suffer from trees enveloping its summit.  So there are stunning views from the top.  This mountain lies within the remains of a massive shield volcano where one can observe the impact of ancient forces.  On the other hand, poor old Brumlow Top hides in the lush Gondwana rainforest, a swelling on a high plateau.  There are no views. It is a fight through the bush even to reach the summit and you would not know it was even there if you weren’t looking for it. 

The Contenders

The contenders are:

1. Brumlow Top – the highest and with more than enough prominence.  It was undoubtedly a part of the Barrington Tops shield volcano.  But there may be some doubt as to whether it was a centre of volcanic activity.  On the other hand it is located more centrally to the Barrington Tops area than Mount Barrington which is at the fringes of that area (see below). It would seem odd if the only eruptive activity occurred at that fringe.
2. Round Mountain – lower than Brumlow Top (just) but higher than Mount Barrington.  Almost certainly the location of a volcanic plug.  However the volcano (if it was one) has mostly eroded away. The mountain now essentially consists of granite with the remnant of a volcanic vent within.  As a result it does not seem appropriate to call Round Mountain a volcano.  Otherwise it has sufficient prominence.
3. Mount Barrington – almost as high as Brumlow Top and probably a centre of volcanic activity.  However even the scientific papers I have seen suggest that this activity may have been “nearby”.  But Mount Barrington does not have much prominence.  It is a bump on the edge of the Barrington Tops plateau. There are two nearby tops higher than it, both of which have greater prominence (in Brumlow Top’s case considerably so).
4. Mount Kaputar – undoubtedly a volcano with sufficient prominence.  A lovely mountain in fact with great views.  It would only get to number one spot if the three above were all discounted.

The table below provides height and prominence details taken from a variety of sources, especially Peakbagger.com, Wikipedia and Google Earth.  There are often material differences between them.  Indeed Wikipedia itself is often inconsistent between pages for the peaks themselves on the one hand and the page with the listing of Australian mountains on the other.  So I have used the details that seem to be the most consistent. I have not looked at sites such as Summitpost or Australian National Park websites because in the end this did not seem to matter for the assessment. 

So I repeat.  I am not a geologist or volcanologist.  Accordingly, my interpretation of the information that I have found may well be incorrect.  I am happy to be challenged on the content and conclusions of this note as to Australia’s highest volcano.

Any volcanologists out there?

The Table

Name of volcano	Contender peaks	Height and prominence	Ranking of contender
Tweed	The Tweed volcano is one of the largest volcanoes in the world. It was originally around 100km in diameter. Its lava flows all the way east to the Pacific Ocean. There remains a 30km diameter caldera wall within the original extent of the volcano. At the centre of the caldera is Wollumbin (also known as Mount Warning) which with its striking shape is a well-known landmark and, despite its relatively lowly height, can be seen out to sea even though it is about 35km from the Pacific coast.
	Wollumbin	H: 1159m/3802ft P: 973m/3192ft	Not ranked although it has more than enough prominence. There are many peaks forming parts of eroded volcanoes that are higher than Wollumbin.
The Tweed volcano also incorporates:	Mount Barney (McPherson Range)	H: 1359m/4459ft P: 766m/2513ft	Australia’s fifth highest volcano.
	Mount Superbus (Main Range)	H: 1372m/4501ft P: 815m/2674ft	Australia’s fourth highest volcano.
	Bar Mountain (Tweed Range)	H: 1130m/3710ft P: Not available (but less than 600m)	No ranking for these purposes.
Therefore the highest points in the McPherson and Main Ranges exceed that of the “parent” Wollumbin. Wollumbin is a volcanic plug. The other three mountains are probably volcanic dykes.
Ebor	The remains of another shield volcano. Round Mountain is its highest point, but erosion has removed much of the original shield, especially in the area of Round Mountain itself. See here and note the line depicting the current landform. Round Mountain has a remnant of a basaltic plug but most of its slopes comprise the original underlying granite. So it is probably not reasonable to classify it as a volcano.
	Round Mountain	H: 1584m/5200ft P: 744m/2441ft	Although it has sufficient prominence, no ranking for the reason given in the commentary.
	Point Lookout	H: 1564m/5131ft P: 224m/735ft	Point Lookout is made up of volcanic rock but is not the site of volcanic activity. Therefore it is not ranked. It also does not have sufficient prominence. If this point were to be ranked then so would any lava field that happened to erode at a slower pace than its source so that it was now at a higher elevation than the source.
Nandewar	The remains of a shield volcano. The highest remaining point is Mount Kaputar which forms a part of the rim of the original volcano. Undoubtedly to be classified as a volcano.
	Mount Kaputar	H: 1509m/4951ft P: 859m/2818ft	Signs at the mountain give a height of 1510m or 4954ft. However Mount Kaputar is lower than Brumlow Top and, if counted, Mount Barrington. So Mount Kaputar is Australia’s second highest volcano.
Barrington	The Barrington volcano is an eroded shield volcano. The highest point is at Brumlow Top. This volcano is heavily eroded and so it is unclear where all of the volcanic activity has been. Mount Barrington has been shown to be at or near an eruption of the volcano and shed its lava over most of the Barrington Tops area.
	Brumlow Top	H: 1586m/5203ft P: 1105m/3625ft	Presently ranked by me as Australia’s highest volcano though there may be some doubt as to whether it was the centre of any volcanic activity. But see here where the discussion on Brumlow Top refers to the highest point being at 1576m. This is the height for Mount Polblue. Mount Polblue was once thought to be the highest point in Barrington Tops until resurvey placed Brumlow Top as higher. Note that my GPS (an Etrex 30) put the height of Brumlow Top at 1595m at the “summit” cairn and 1597m at the point shown on the Peakbagger app as being the summit. [See also my Peakbagger trip report]
	Mount Barrington	H: 1555m/5102ft P: 81m/266ft	With a prominence of less than 100m (assuming Google Earth to be correct) it does not “deserve” to rank as a continental high point. However, it should probably properly be classed as a volcano.
Canobolas	Another eroded shield volcano.
	Mount Canobolas	H: 1395m/4577ft P: 674m/2211ft	Australia’s third highest volcano.