Lava Blisters AKA Tumuli near Byaduk, Victoria, Australia

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Robin Whittle  25 October 2026  rw@firstpr.com.au




Lava blisters are a rare geological formation as a crust of a fresh molten lava flow, which solidifies and is pushed upwards into mounds which remain to this day.

The Nomadic Explorer family, originally from Kazakhstan, visited in 2013: thenomadicexplorers.com/content/about .  Here is the diagram they made, which explains the formation process:


There are various web pages on this formation: www.google.com/search?q=%22lava+blisters%22+Byaduk&lr= .

However, few have detailed photos.  Here are ours.  First, directions on how to get there:

Google maps location www.google.com/maps/@-37.939338,141.8900589,1875m/  Lat, lon: -37.937, 141.885.


This is on Old Crusher Road, 5km west of the junction with Harpers Rd, which can be accessed from the Hamilton - Port Fairy Rd:  





Here is the location, within south-west Victoria, with BD indicating the location of the volcanic Byaduk Caves, just west of the volcano Mount Napier:


To the south is the Mt Eccles (Buj Bim National Park), with its lava cave, lava tubes, lava lake and lava channels, where the molten rock melted its way as it flowed, through the basalt formed by previous flows, and then drained away towards the ocean, leaving a channel 20 to 70 metres wide, and 6 to 10 metres deep.  (Watch out for leeches!)  https://www.google.com/maps/@-38.0713214,141.906557,219m/.  -38.07118, 141.90661.

Mt Napier en.wikipedia.org/wiki/Mount_Napier erupted about 32,000 years ago.  It rises 150 metres above the surrounding lava plains.   From that page, a map of the area:



By KenG44 - Compiled by me in Corel Draw, for use in a variety of talks, handouts, field guides, interpretation signs etc Previously published: Versions have appeared in Field Guides etc., CC BY-SA 3.0, commons.wikimedia.org/w/index.php?curid=21451910


There is a magnificent guide to many Victorian volcanos, at least in the west of the state.  It it is an excursion guide from a 1993 tour of the area, following a conference in Canberra of the International Association of Volcanology and Chemistry of the Earth's Interior www.iavceivolcano.org.  This includes:




Ollier 1964: Volcanic Physiolography of the Western Plains of  Victoria, C. D. Ollier and E.B. Joyce.  The Basalt Plains of Western Victoria Symposium 12 September 1963, PDF pages 127 to 150, Proceedings of the Royal Society of Victoria [1964]. Vol. 77 (New Series). Part 2 - get the PDF via the download icon at the bottom right of: viewer.slv.vic.gov.au/?entity=IE12667448&mode=browse.

Here is the relevant section.  The last sentence refers to the curve in the Harman Valley flow, which I think is directly north of the lava blisters site, with the site forming as a dead-end side-branch as some of the lava advanced up a shallow valley, to the east-south-east, for about 3 km.

I think this means that the lava which flowed into this area then remained quite static, while the lava in the main channel kept flowing.




See my notes at the end of this page, about the formation process and the last photo, which may be evidence of gas, rather than molten rock, pushing up the blister or at least being part of a curved structure associated with these blisters.  This is highly speculative, since the observation of the geologists is that they found no hollow blisters.




In October 2026, I cannot figure out how to navigate the Victorian Government maps system.   The 1:250,000 Hamilton Geological Map is at https://gsv.vic.gov.au/SearchAssistant2/details?q=internal_id:11169.   An excerpt with B for the site of the lava blisters:




 
There is a TUMULI LAVA BLISTERS signpost and a gate at www.google.com/maps/@-37.9377419,141.8850396,133m/ . 

When we visited in July 2017, there was no lock on the gate.  I don't know what the situation is now, in 2026. 

The lava blisters are on private farming land.

Some web pages suggest viewing from the road.

Here was our reasoning for venturing into the property to get a closer look.  We make no claims about the legal veracity and moral rectitude of our decision.

If this was our land, we might not want to encourage or support people walking in, due to potential legal and insurance complications, and also to discourage those with only a passing interest in geology.

If we wanted to keep people out, we would install a warning sign to this effect, and keep the gate locked.

We would want responsible, appreciative people to be able to experience these geological formations, so we wouldn't lock the gate.

The implication being that anyone who entered did so at their own risk, and should tread lightly, watch out for bulls, snakes and leeches - and leave no rubbish behind.

















































Drystone walls made by stacking basalt boulders.
























Ollier 1964, above, states "We have not been able to find any hollow blisters".

They attribute the formation of the blisters entirely to pressure from lava.

However . . .   why would heavy lava rise up like this, some of it evidently above the elevation of the top surface in the crust surrounding it, pushing up the stiff crust to such heights above the top of the rest of the crust, that the elevation of the top of the molten lava below the highest part of the now dome-like crust is, I guess, above the top of the surrounding, level, crust? 

This does not make sense from a hydrodynamic point of view, any more than does the idea of a patch of liquid water in a top-frozen lake rising up to push the ice above it into a dome.

Ollier refers to the intense bending of the crust at the top of the blister causing it to open up with cracks, which can be seen in photos above.

While hollow arch-like formation pictured above is arguably not that of a proper lava blister, it looks hollow, as if it was pushed up by gas - and the rock above it looks like it has been bent upwards to some extent.

Alternatively, it might have been pushed up by lava which subsequently drained away.  But why would that happen? 

The whole body of recently arrived lava is no longer moving.  It is cooling from the top with cool air and radiating its heat into space, while it is sitting on cold rock, only metres below.

It is easy to imagine the lava heating some water in the rock below and this rising as high-pressure steam with enough pressure to push up, and deform, the still somewhat plastic lava, which I guess would be red-hot inside, with the outside crust not radiating much in the visible spectrum - until the cracks appeared.




~~~ooo000ooo~~~