Rock art conservation: impact of microclimates on reactions of the environment with the engravings

Video | Updated 2 years ago

Presented by Dr Ian D. MacLeod, Executive Director, Fremantle Museums and Collections, Western Australian Maritime Museum

Part of the WA Museum’s 2014 In the Wild West Lecture Series.

The remarkable rock engravings found in the Burrup Peninsular are internationally acknowledged as being rich in diversity and intensity.  Rock engravings in the Burrup are subject to natural weathering in an arid and hot climate.

Dr Ian MacLeod has spent 35 years studying the decay of materials in the cultural landscape and has worked on conservation of rock art in the Kimberley, Murchison and in the Wheatbelt. Dr MacLeod will present the results of a study on the chemistry of the rock surfaces and the impact that natural and man-made materials have on the micro-organisms that control the rate of biodeterioration on the rocks.

Rangelands Natural Resource Management is the Presenting Partner of the 2014 In the Wild West series.

Rangelands NRM


Ian MacLeod: As you probably gathered from the introduction, I'm a chemist and quite proud of that, and also I'm a conservator and also a Museum Director, and people say, ‘Well, how can you be all of those?’ and the answer is very simple. I'm just me. But what I'm going to do is give you, I hope, a bit of an insight into the complexities of the issues surrounding the preservation of the rock engravings in the Burrup.

Now, for those of you who aren't familiar with the Burrup, the area contains perhaps the greatest number of rock engravings over a small area that there are in the world. So it's significant on an international scale, and there has been an awful lot of misinformation in the media about rock art and how rapidly it's degrading; and ‘What's going to happen?’ and ‘What are we doing?’ and ‘How can you have your industrial development right in the heart of this cultural landscape?’ and – you know – and the answer is it's complex. All of life is complex.

I look at all of you. You've all got different faces, you've all got a different posture, you're all breathing at subtly different rates, so every one of you is like another rock engraving. You can't assume that you know everything about the rocks. You have to come up to them and subtly interrogate them, talk to them, ask them how they're going – you know – ‘What was last night like for you?’ and they will tell you. You just have to learn the language of decay, and that's something that I've learned over the last 35 years. So it means that I can come up to an object underwater or to a cathedral standing on St George's Terrace or to rocks in the Burrup and I just sit down and we have a chat and try and work out chemically, environmentally what's going on.

So in the talk tonight you'll see a lot of [Microsoft] Excel graphs and that's because you need to understand the connectivity between biological activity, the acidity of the environment and also the natural impact of salt spray on the rocks. So … I don't expect you to remember everything [I say]. There will be no test at the end of the talk, but I hope I will give you an insight into some of the complexities that there are in the natural environment.

[Addresses screen] So… for those of you who aren't familiar with the Burrup rock art, this is the view of the famous – the most famous engraving on the … [in the area and] on the site – and the so-called ‘climbing man panel’ which traditional owners say is images of people climbing up on the tree of life and meeting different animals and creatures in their journey, … and it's not up to me to do interpretations of the symbolism and the meaning of the engravings. It's up to me to try and understand what's going on with their decay, but before we journey on there – this purply black material is called ‘desert varnish’ and there have been dozens of papers written about what is the nature of desert varnish, and it's still somewhat open to debate – but the reason why you've got that purply-black colour is these rocks are granophyre and gabbro rocks, and as they weather over the millennia and well, millions of years, they build up a layer of degraded rock on the surface. And so the Aboriginal people would get instruments and chip their way through this pattern and create the rock art. One mistake, … boof, ruined. It's a bit like Michelangelo, … you’re doing David and one little wrong blow with your hammer and chisel – woops, all gone. Start again. And so, pretty important to get it right.

[Addresses screen] And one of the things about the climbing man panel – that's me wearing my hat and keeping the sun off – the climbing man panel is there, and there's Woodside's new production facility, … and people would say, ‘Oh, oh, look at all the smoke and all the pollution. It's destroying everybody. The health of people in Karratha and in Dampier is being ruined. They have higher cancer rates because of the industrial pollution from the Burrup,’ … absolute poppycock, and the reason why gas and oil production facilities have flare towers is they burn the naturally-produced, highly toxic, polysulphide materials that are there in the condensate and in amongst the gas. If they didn't burn them they would have a big (do come in Nicola) … they would have a big storage and a pollution problem. So they flare them periodically and – you know – it's big and looks … you see these flames leaping out and you think, ‘I'm in hell.’ No, ‘I'm in the Burrup.’ And so what we had to do was work out ‘Are these NOx?’ – that's a mixture of nitrogen dioxide and nitrous oxide – ‘Is it having an effect on the decay of the rock art?’ and the reason why I say beware of simplistic answers is, … well, if you think you know what you're talking about, you're 90 percent wrong, unless you've heard my talk before.

So, what we did was we worked out [the chemistry of the rock surfaces and]… we had to be systematic. So these are some of the rocks that were put into the so-called museum compound. Now first of all, we now know 25-35 years later that was not a smart thing to do. The rocks had to be moved there because they were in the road of the first Woodside plant and it was agreed with the traditional owners that the rocks could be uplifted, put in a compound to save them from vandalism. And one of the things was that all the rock engravings were always … [they were traditionally positioned so that they] had a vertical aspect and some of the rocks were put lying down horizontally, and others that were secret and sacred material were put face down; and with the benefit of hindsight, that wasn't the best way to treat it [them] because if water is not freely draining from the surface then you're not [keeping the same environment and so]… you're altering the chemical balance of the rocks and so therefore things will change.

[Addresses screen] So what I did was I went and used set areas of [rock, defined] … with a plastic – with a polyester sheet – and I rolled cotton buds (bought from Coles because it was cheaper) [over the surfaces to get microbiological samples for analysis] … and you roll them over a set area and put them into sterile tubes, and one my friends at the Department of Agriculture cultivated the yeast, moulds and fungi for me. So to make sure that we didn't have the material going off, we had ice in [around] the vials so that we would get accurate results; … and just as well because that is 55 degrees in the shade, and when you're out working on the Burrup and sitting on the rocks, there is no shade, and I thought at one stage, ‘Gosh this is hot,’ and I put my digital thermometer on the rock and it was 67[°C], and so … and when your bare … back of your bare leg hits a 67-degree rock, you move very quickly.

So that was the first thing. We wanted to go and look at [the impact of microflora and] get counts of the yeast, moulds and fungi that are naturally there in the environment because it's those weathering reactions of all the hyphae from the organisms reaching into that crusty rock that control the amount of by-products which go and feed on the rock and therefore control the rate of decay. Being a good little chemist I knew that salt was another important weathering agent … because anyone who's been up in the Pilbara knows that those winds, they fair do blow and they come in from the sea and they bring salt spray and mist with them.

So therefore we could get an idea of what the underlying weathering effects from all the salt would be if we just went around with a surface sensitive chloride electrode [and measure the amount of available salt]. And so we'd put a drop or two of distilled water on the rock … and these rocks are tricky. Sometimes they say, ‘I'm not going to tell you how much chloride I've got on me,’ and they just go … [and] suck in the water. Another couple of drops … I say ‘Please, please, let me measure you. I'll be very kind,’ and after another few more drops it says ‘Okay,’ and then it lets you get a result, and so we'd just write down on a piece of paper what the results are.

[Addresses screen] And as you can see from the sweat on my hand, it was getting quite warm, but I was smart [and used sunscreen]. Don't (ignore the brand) ... but there was water on hand. And there you can see some engravings. Now … the form of documentation of the rocks when these were removed 30 years ago into the compound was not particularly subtle. They used standard paint that you use when you're tagging cattle or – you know – or anything that moves, and because the rocks were being moved, they used some good old white paint.

[Addresses screen] But it's a good test. If you want a good paint in the Pilbara, use that one. So … these are typical of the images that are engraved. At least here the rock was still in its vertical orientation, and like … we had a flat surface chloride electrode, [and] we had a flat surface glass [pH] electrode [to get our measurements with]. And you can see a bit of a dribble line of the moisture down the side of the rock, … and it takes about a minute and a half to get a steady reading. And so we were able to get readings on all the various sample rocks in the compound, away from the compound, away from industrial activity and we went all around the Dampier Archipelago doing sampling and because we wanted to make sure that we had representative results.

And … ah, next trick was developing a system whereby we could take samples of [water soluble minerals from] the surface. [Addresses screen] So I got some high-density polyethylene foam, stuck it to the bottom of a Perspex tube and then we poured in a standard amount of water. So I know it seems funny to go all the way up to the Pilbara with water and wash bottles and stuff like that, but unless you wash your rocks you don't know what's on the surface. So … some of you may enjoy a bath, some of you may prefer a shower. These rocks got a bath by courtesy of the Museum. So what we would do is equilibrate the water on the surface of the rock for a set period of time and then use a hypodermic syringe to suck up the solution and then that was analysed at the ChemCentre of WA.

Chemists like most people use acronyms. [Addresses screen] ICP-MS means inductively coupled plasma mass spectrometry. What it means is it is so sensitive if someone spat on the rock with a radioactive compound in their teeth, you would pick it up 20 years later. So it's very sensitive and it tells you what the mineral composition, the soluble mineral composition of the rock surfaces are. So we had the chloride, the pH, the number of yeast, moulds and fungi, and the composition of the surface of the rock. Therefore we thought, ‘Uh-huh, we have a chance of understanding what's going on.’

And so we went up in the Mermaid Sound. [Addresses screen] There's me. No, that's Warren Fish. My friend Warren Fish was then Registrar of Aboriginal Sites. He had money. I didn't. Warren paid for my four trips to the Burrup, so I'm very grateful to him, and that was Mance Lofgren, the former Curator of Anthropology in the Museum, and this [location] is half a day's steaming on that boat, up away from Karratha onto Dolphin Island and where [we took our measurements on local rocks] … because we all wanted to get some samples that are well away from any industrial activity.

And so the whole issue is bacteria, yeast, moulds and fungi have acidic metabolites and so therefore one of the counteracting effects of the sea spray, because salt water is alkaline, and as it dries, it becomes increasingly alkaline, therefore the salt spray can inherently balance out the natural acidity from the normal biodeterioration of rock and so help slow down decay, … and that's what we found.

For those of you … and I know Loisette [Marsh] in the audience is an old experienced fieldwork operator in the marine environment … when there's no water other than to drink, you wash in salt water, and one advantage of washing in salt water for weeks is you don't get smelly armpits; and it's because the alkalinity of the seawater kills off all the bacteria, and so – or at least keeps them at a nice low level – and so there is no lactic acid to live on in your armpits, therefore no pong. So … if you run out of shower water, just regularly go for a swim in the Indian Ocean and you'll be fine and still be socially acceptable even in the best of company.

[Addresses screen] Right, here's the first graph and I'll walk you through it. Here is in milligrams per litre or parts per million, the amount of chloride on the surface of the rocks. And a hundred milligrams per litre is 0.1 gram a litre, and if you went … it'd taste salty. And so what we found was … and here's the pH with the lower values. pH 4.0 [which] is about the level of [acidity in] vinegar, pH 6.0 is 10 times more acidic than pH 7.0. So pH is a logarithmic scale. A separation of one unit means a difference of tenfold in acidity or alkalinity.

[Addresses screen] So you can see the pH varied from about 4.2 … or something up to about 5.5. So … it's on the acidic side – there's neutral up there – so it's all acidic. [Referring to graph] And we found a series of dot, dot, dot, dots. So we had orangey colour, our greens and blues and purples, and a few spots in between that didn't join on, and interestingly these couple of linear relationships that the intercept value of 4.07 – that is when there was no chloride – and 3.25 … this line here was clearly a very different chemical environment to the one over there. So even though it's just measuring the chloride and the acidity, there's something different in the way in which the rocks there and there are behaving. So what that immediately told us was … it ain't simple. It's complex. You've got to look at the patina of the rock. You've got to look at the different substrates, whether they're granophyre or gabbro rocks, and that's where you’ll begin to start to get an understanding.

[Addresses screen] And here is an engraving –- beautiful zoomorphic creature – and here are the results of the acidity … around about 5.0, 4.0, 3.5, 5.0, almost 4.0, almost 4.0. So that … that's quite a significant variation, a tenfold difference in acidity between the bottom and the top of the rock. So therefore with that difference in acidity it means that the chemical dissolution reactions of the patina on the rock will be varying, and so that is just on one rock that's only that big. So … we've got our work cut out for us.

[Addresses screen] And what we found was that here we've got – so back in the left-hand corner –  it's very acid at pH 3.0, 4.0 is vinegar and 6.0 is over there. What we found was here's … here's the number of bacteria and ‘ho, ho, ho, ha, ha, ha, vroom, vroom, vroom’ what it means is that you are getting the acidity increasing as the number of yeast, moulds and fungi go up. So as this line is the number of bacteria [which] went up, ‘vroom’, the acidity [also] went up. But look, these are essentially parallel lines and so the slopes of 39 points [of measurement] – you know, 39,000, 39,000, 36, whatever, 37 – [it shows that they are] all … experimentally they're the same slope. So that means there is a common mechanism connecting the number of yeast, moulds and fungi, and the acidity. So that means even though the values may be varying over the rocks in different parts of the Burrup, you've got a common mechanism, and unless you understand a  mechanism of decay, you're never going to be in the right situation of being able to work out what's going on, … and if you know what's going on, you've got a chance of managing it.

And so it's a bit like the traffic  [that] change[s] and snarls with Riverside Drive being dug up. Now you may say ‘What is the connection between traffic and Riverside Drive and rock art in the Burrup?’ It's all [about] understanding the mechanism. In the case of the traffic snarls in Perth, it's the mechanism of Perth … traditional car drivers who have got so used to driving down particular roads all the time, they still do it even though the roads are being dug up, and then it takes time for them to learn a new pattern. Well … the rocks are smarter than the average Perth drivers because they conform to the same mechanism of decay no matter where the surface is oriented or – you know – where the acidity came from or whether it's this rock or that.

So … sometimes people say, ‘It's just rock. What does it know what it's doing?’ The rock knows very well what it's doing. It's responding to the changes in the chemical and physical environment created by the things that are living on it.

[Addresses screen] And I owe a lot of gratitude to the late Pat Vinnicombe who used to be a rock art guru in the Department of Aboriginal Affairs, or DIA as it was then [and who taught me heaps about the power of the rock art], … and here's one of the engravings. This is what the rocks look like in the valleys, just massive piles of these ancient shattered rocks that have got a beautiful varnish on … and there is another engraving, and it is totally awesome.

You are up there at different times of the morning and the day and the evening, and you walk around, and you see as the sun hits different parts, you say: ‘I didn't see that before,’; ‘Who did that?’; ‘Hey?’ … ‘Who's drawing rock art?’. No … no-one's done on it … you, it's just you don't see it because when these images were engraved, the rocks began to repatinate, and so slowly the engravings are disappearing, naturally over time. And so therefore you often need subtle angles of light to be able to pick up the engravings, and at different times of the seasons you will see images of the wallabies or the goannas, or the dugong or the turtles coming into if you like, full view of where you're camping, and … and that was associated with the stories of the increase, that when the sun was tracking and moving over these images, that's when it was time to go hunting after those foods.

So some people say, ‘Well it's just a giant food catalogue and we get them shoved in our mailboxes today by Coles and Woolworths saying “buy this”, “buy this now”.’ Well, tens of thousands of years ago perhaps the elders were saying, ‘Well, go and hunt this now,’ and Pat had led this group of us up into the Burrup to talk about the rock art and the engravings, and she was saying to me on one night, ‘Look, I don't know how much longer I'm going to be around. Will you promise me that you will care for the rocks?’, and I said ‘Yes.’ She said, ‘Well, I know you will,’ and the next day she died.

And so she had – like many Aboriginal people do – an understanding that death was coming close and so she discharged her responsibility for the rocks to me, and so hopefully before I go, I will be able to charge someone else with caring for the rocks.

[Addresses screen] And so here's your next graph – I said there would be a lot of graphs – and what we did, we looked at the amount of nitrate … and those of you who have lawns, know that if you want your lawn to go green and look healthy, you put nitrate fertiliser on it … and here was the level of nitrate, not much, but quite measurable amounts, and here is the log of the number of yeasts and well, bacteria. So, there's a direct relationship, logarithmic relationship, between the amount on these different types of rocks … between the amount of nitrate and the number of bacteria. So that tells you – surprise, surprise – nitrogen is a limiting agent for biological activity in hot, dry, arid environment. So, where does the nitrogen come from?

Well, up in the sky there's a lot of nitrogen during a lightning storm. The high energy of a lightning discharge makes normal nitrogen and oxygen react to form nitrogen oxides which then come down as acidic rain … and for example, the rain that falls in the Kimberley can be as low as pH 3.5 when it hits the ground. So having … having acidic rain is quite natural but also if there is man-made sources of nitrogen oxides in the air, then they will come down also as acid rain.

[Addresses screen] And so you can see here I hope, that these different coloured surfaces with the engravings on, they look different don't they? [Addresses audience] Can you tell that they're different? Yes? Yes, yes. Thank you, and remember all these parallel lines with different intercepts? That's just saying, ‘I've got a different mineralogy to you, but I've got a common mechanism that's controlling my rate of decay.’ So that's why these engravings will be behaving in a different way to these ones because the minerals there are different. I mean obviously there are a lot of iron-containing minerals because of the red-brown, but they're subtly different, just like all of your hairstyles in here is wonderfully different and you're all human, but you're subtly different. You've [got] different dresses, clothes, trousers, shoes, … so you're like the rocks in the Burrup: quite diverse, basically connected. Half of you are women, half of you are men, so one of you may be like gabbro, the other might be like granophyre, but you've still got connections.

[Addresses screen] And one of the other things that varies enormously is the roughness of the rock, … and if a rock is microporous, then the yeast, moulds and fungi, they just go in and go  ‘Ha, ha, ha, ha. I'm hiding,’ [they say]. I says, ‘Well what are you hiding from?’ ‘The sun,’ … because you … when you are being cooked to 50-60 degrees, you're really being pushed to survive. So what you do is you go into these tiny crevices in the rock where the capillary action is so fine that moisture is still there for you. So you don't die. You [survive] … living may be difficult, but you wait around, [then] night-time dew condensation comes, you've got enough moisture … you go and reproduce, produce a bit of acid, dissolve a bit of rock, get some minerals and you live a happy life, … until the next morning comes and the sun comes up and tries to cook you to death. So, if you think life in Perth is difficult, try being a bacterium living on the surface of the rocks in the Burrup. I'll tell you who's got the better deal.

[Addresses screen] And the other thing that I was alluding to before, is that here is the surface pH and getting quite acidic, … you're down to 3.5. So that's about five times more acidic than vinegar that you have on your fish and chips if you like vinegar. (I don't. It makes me cough.) And so there's quite a difference between this intercept value at about 4.1 and that at about 5.6, but again, you've got these parallel lines and these are rocks from different parts of the Dampier Archipelago in different parts of the Burrup. So … their chemistry is different but you've got a common mechanism. So it means though, that the higher the amount of nitrate, the more bacteria will be [present] and as the nitrate goes up, the acidity increases. So that's an important thing to remember.

[Addresses screen, referring to graph] And the colour, the size [of the] the font of the [letter] ‘N’, is an indication of the amount of nitrogen and so – you know, down here, Dampier West – very low nitrogen, … more there, stuff all there and around here there's a lot of nitrogen, and so … and that's where the Museum compound was, Deep Gorge where a lot of the rock art is. So … you know, there was a big amount of nitrogen – surprise, surprise – within the vicinity of the gas plant. So, when I showed these preliminary results to people at Woodside they were quite concerned and then they said, ‘Well, can we look at your data?’ So I gave it to them all and people said to me, ‘How can you give Woodside your data?’ I said, ‘Well unless they can look at it and examine it for themselves – you know – how do they know whether what I'm talking is a load of rubbish or not?’ I could be totally off the mark. I may not know what I'm talking about.

And so they brought me [in for a meeting] and we had a chat, and as a result Woodside went and brought forward their plans to change the burners where they burn natural gas to get energy to drive – you know the complex plant - and they changed all their burners to being ceramic-lined which produces far less nitrogen oxides and their emissions just went [indicates downwards]. So now the Pluto, the next big gas train is running, … they are producing less nitrogen oxide emissions than they were when I began my work, and they've doubled the size of their plant and so the air quality up there in terms of nitrogen is … is much better.

But don't be tricked, because right up at the top of the Dampier Archipelago, I got my equally-high nitrogen concentration, and you say, ‘How can that be? It's away from prevailing winds.’ Yeah, it was near some euro poo [small rock wallaby scats] and – you know – I'd sampled the rock art, done all my measurements and then I noticed the poop. It was dried poop, but it was still enough poop to give plenty of nitrogen to the rock surface. And so there I was measuring quite acidic rock surfaces dozens and dozens of miles away from Woodside [operations], and it equalled the concentration of the emissions [near] at [the] Woodside [plant]. So, if I hadn't gone far away from the [Woodside plant] point – [the] ‘apparent’ point source of the nitrogen - I wouldn't have known that:  where … [where nature can match industry for creation of environmental nitrate and therefore] where the balance point [of decay] is. So, I just think it's quite telling.

[Addresses screen] And so we also found … we looked at the amount of sulphates and people go and say, ‘Oh,’ – you know – ‘there's industrial pollution in the Burrup,’ or ‘The sulphur dioxide is producing acid and it's killing everything.’ Wrong. But in fact a lot  [or at least]… some of the sulphur dioxide comes from shipping. They burn … the iron ore ships burn bunker fuel and it stinks, but you can smell that in Freo, and also cars are burning diesel, often produce emissions, … but this stuff, dimethyl sulphide is a natural by-product from good healthy seaweeds living in the ocean. So dimethyl sulphide [comes out of the sea and then it] gets oxidised in the air to produce sulphur oxides and that explains – as you can all read – the high levels of SOx at Dolphin Island way up in the Archipelago because the environment is absolutely pristine and it's naturally biologically-produced sulphur oxides. So, just when you think you've got something good to talk about, nature intervenes and corrects you.

[Addresses screen] And so what it is, that's why we've got – here we are – we've got these different lines. You can see lots and lots along there.  That's because the rocks are common, and there's a connection between chloride there and sulphate. The normal ratio is along there because you've got sulphate salts in seawater and chloride [salts as well]. So you've got basically deposition of sea salts on the rocks. But some of them have different activities and the ones … the cause of the difference here is [due to these rocks, contained in which] there are a whole series of little micro fossils, cute little things living – well they were once, rest their soul in peace – but they were living in the rocks and became part of the rocks, and because of the calcium carbonate, when it finds sulphate on it, it reacts to form gypsum [CaSO4.2H2O].

[Addresses screen] So, we were able to pick up the difference in the micro-morphology and mineralogy of these sulphate containing rocks, the normal gabbro and granophyre and these ones up here, were downstream from the major iron ore loading facilities. So … this is extra sulphate from the burning of the oil that keeps the ships running. So just how good are those rocks? They tell you how much salt's there, they differentiate between the source of sulphur, they tell you how many yeasts, moulds and fungi are there, and they – and what minerals are being solubilised – they tell you everything. So, if next time you're going for a walk in the bush, just remember sit down and talk to the rocks and they've got a lot to tell you.

[Addresses screen] And one of the things was in this famous turtle image, you can see that even though this is black and white, this was the rock when it was faced up in the compound and 20 years later some of the subtlety of the engravings has been lost, … and that's what we found was, … we would never again allow rocks to be oriented face up because it allows the water to pool, it allows yeasts, moulds and fungi to live longer, produce more acidic metabolites and therefore accelerate the ageing of the rocks.

[Addresses screen] And one of the things was people go and say, ‘Well how reproducible is this? You … you may just be creating artefacts by your measurements,’ and I find that really quite offensive. People go – and think that you would go – and rig your results just to prove a point? No. The results speak for themselves.

[Addresses screen] And here on the same rock surfaces – we went back in different seasons – and pH is different, and what the main variable here with the different results is, … moisture, [in the form of] rainfall. When there's more rainfall or – you know – there have been rain events, you've got a different acidity, same NOx, same engravings, [react to create a] different [micro-] environment.

[Addresses screen] And so that's why you get here on this different graph, in these cases you can get some areas, some rocks where they decrease in acidity and that's because of their orientation and the amount of rain they've had. It's washed acidic metabolites off the rock and so it becomes more alkaline and therefore rates of dissolution of the minerals goes down.

In some cases you get increase in acidity and that's due to moisture being available to the yeast, moulds and fungi. They go and regenerate, grow as fast as they can and so it changes. So, therefore rain can be good or it can be bad, but in the balance it all works out.

[Addresses screen] And look at this for reproducible results. Went back and on three different areas there are the results of pH and that's incredibly reproducible. If anyone's done real experimental work in the field looking at the variability of rocks, getting results that can track over the seasons as close as that means that you're onto something good.

[Addresses screen] And look  – this is probably a bit hairy for you – but I have to admit that I prayed for rain. We went up there, storms were meant to be coming and I desperately needed [rain] … it was a really hot time of the year and so I said – you know – well, I won't say my communication was with God, but I asked for rain and then in three days … down came the rain, and then we were out going back to the site, re-measuring the rocks and seeing how quickly they'd responded, and they did. They said ‘Yum, yum, yum, yum, yum, yum,’ and … and so the main thing to note that for some of the areas there was very little difference in the acidity, but here's in the dry there was 22 groups of yeasts and moulds, there [in another dry location were] 144, 402. So, there isn't necessarily always a direct correlation between the population and the acidity because some yeasts and moulds produce fairly neutral metabolites.

[Addresses screen] So clearly in this case, in the Burrup South West 1 area, there was very little difference in the acidity and yet there was – you know – a huge difference in the number of yeasts and moulds and fungi, but in this case there … there were [results showing an] eight [-fold increase]. It went up with the rain to 232 and, but look – look at how the acidity fell on that one. Different organisms and – going, ‘Zoom, zoom, zoom, brrrr,’ – up and down [the graph scale] like blinking yo-yos. So, clearly here these organisms were producing a lot of acidic metabolites and … and these ones were not. So … the main thing to note there is the variability of the results. So it's not one story fits all. You have to know your rocks and do your measurements and do them over several seasons before you can reach any valid conclusion.

[Addresses screen] And that just gives you a view of some of those little yeasts, moulds and fungi as they were doing their stuff on … in the culture medium and I owe another debt of gratitude to Ian Arthur at the QE2 pathology centre. They are normally used to dealing with growths of organisms on human flesh and infections after operations, and so they kindly obliged the Museum and did measurements free of charge for me, and in return I've given them special tours of Shipwreck Museum for their friends and families and conference delegates. What goes around comes around. You look after people, they look after you.

[Addresses screen] And so look, … it is an extraordinary environment and … and so there's Mance, there's Warren. Warren's about six foot five, [with giant] shoulders on him – you know, like that [gestures] – taught me heaps and these … this is just a view of some of the incredible worn granophyre and gabbro ranges and rocks, and upon these you have tens of thousands of thousands of rock engravings. If you haven't been to the Burrup, go up there, get a tour with some of the traditional owners and you will have your socks blown off. It is absolutely stunning.

[Addresses screen] And therefore currently there's still [monitoring] going on … the government is funding and the industries in the Burrup Peninsula are funding monitoring [of] sites. That's where we did the work on Dolphin Island, and this is where there are currently CSIRO recording devices and the Mardie Station is the reference point way away from anywhere. And so there's still monitoring going on up there for another four or five years so that we can look at some longitudinal trends and work out what … what the right answer is.

And so we don't know it all, but hopefully now at the end of my talk you have got a bit more of a feeling for the remarkable complexity of the interaction of the natural environment with the rocks and yeah, … have a feeling and an understanding that yeah, it's beautiful, but it is ultimately going to all decay, but that may take another 30 or 40,000 years. So who knows if Canberra will still be there taking all our GST or if we will have done the right thing – I can't say that – and have seceded from the rest of the country, … but look, in WA it doesn't matter whether you go into the Wheatbelt, into the Pilbara or into the Kimberley, or in deep in the South-West, we live in a really beautiful part of the world, and also we're extraordinarily lucky to be able to engage with the longest ever recorded group of … of traditional owners and people who've been living on the land for more than 55,000 years. So, we're pretty lucky in WA and I'm lucky that you came along to my talk. So thank you very much.