New Zealand volcanoes going for gold

While they might be 19th on the medal table, the kiwis are doing a sterling job of heading up this weeks volcano news.

Both White Island and Tongaririo have shown activity this week. White Island was last active in 1980, and is a beautiful example of an andesite volcano. Tongariro is a volcanic complex, comprising numerous adjacent vents. Technically, it includes Ngauruhoe (a volcano I have spent some time on, and wrote about back in January).

This morning we then get news that a huge pumice raft has been spotted 1000 km North of Auckland, believed to have been generated by a submarine eruption from Monowai.

The first thing I should point out is that these three eruptions are not related. This is just one of those statistical anomalies that crop up with random scatter. All three volcanoes are associated with the subduction of the Pacific plate under the Indian-Australian plate, but their magma plumbing systems are completely unrelated. To put the magma plumbing in perspective, the crust is 35-40 km thick, and the distance between White Island and Tongariro (the closest two of these events) is about 220 km in a straight line. These two volcanoes lie at approximately the NE / SW extents of the Taupo Volcanic Zone (VTZ), and have the much larger features of Rotorua and Taupo separating them. Below is a map which plots the recognised features of the TVZ (taken directly from here and plotted in Google Earth), with White Island and Tongariro highlighted.

Importantly, the Monowai seamount – although associated with the same tectonic boundary (the Kermadec trench), is clearly not directly associated with activity over 1400 km away.

 

The Kermadec/Tonga trench is itself an interesting feature. At over 10 km deep in places, it is one of the deepest trenches known, and with a closure rate of 24 cm per year at the northern end, and perhaps as low as 4.5 cm per year at the southern, is something of an anomaly.

The eruptions we’ve seen from Tongariro and White Island have been small. The Tongariro event was particularly interesting as while there was some indication of rising activity 2-3 weeks ago, there was no immediate precursor activity. The seismic trace below is for the 24 hour window in which the eruption started.  The drum is timestamped in the top right, and each horizontal trace represents 1 hour (numbered in hours before timestamp). All seismic traces here courtesy of GNS Science.

 

That lack of build up activity is good to highlight. One of the biggest issues volcanologists face is trying to provide some level of forecasting for eruptions. The simple fact is (and this event proves) that while we can monitor all we like, even with light-speed communication, eruptions are not nice orderly events which lend themselves to easy forecasting.

Below are two more seismic drums, from the last 24 hours at two separate locations on Tongariro.

 

 

The red lines indicate points where the signal was stronger than the drum could record. You can see the constant activity in the second trace 7-14 hours ago, which is likely to represent magma movement within the plumbing system, similar to that demonstrated at El Hierro for example. The alert level at Tongariro is 2 (minor eruptive activity), and its aviation colour code is down to yellow  (down from red at the onset of eruption).

The White Island eruptions are somewhat more significant – not least because while Tongariro (exluding Ngauruhoe) has not been active for over 100 years, White Island was last active in 2001, following 25 years of activity. This is the seisimic trace from White Island:

 

And it’s looked like that pretty much constantly since Sunday.

So, with everything from rhyolite/obsidian eruptions, to the largest eruption seen on Earth in the last 5000 years, the TVZ is a fascinating study. It is related to a complex plate boundary system, as it transitions from subduction to transform (before reversing its subduction direction West of South Island), and on the whole a great place to do some geology.

 

There’s some great videos and images collated by Erik Klemetti over at the Eruptions blog which are well worth having a look at.

New age proposed for Giants Causeway

UPDATE: The National Trust have released a statement, stating that the NT supports the scientific explanation, but that they simply highlight “that for some the debate continues”. To me, that still doesn’t fix the fundamental issue at play. There’s a lot of people who believe some very weird stuff – it doesn’t mean they are opinions which should be given oxygen.

—–

The National Trust have opened a new visitor centre at one of the UK’s greatest World Heritage sites. What’s particularly of note is that – in a display of bombastic ridicule-attracting lunacy – they’ve included an explanation of the Giants Causeway formation which proposes that it’s no more than 5000 years old.

Their defense of this act of belligerent ignorance is that they wanted to

 ”reflect and respect” the fact that some people contest the views of mainstream science.

Frankly, if we’re going down that route, presumably they’ll also be opening displays supporting the Expanding Earth hypothesis, the idea that the sun rotates around the Earth, and that aliens live amongst us. Actually, that last one might have some truth in it.

I’m not going to pretend that the National Trust has any mandate to do science right, or even that education is part of its aims (“The National Trust was founded in 1895 to promote and look after places of historic beauty permanently for the benefit of the nation across England, Wales and Northern Island. Our core purpose is to look after special places for ever, for everyone.”).  However, as an organisation which takes a great deal of effort to educate people about the places it cares for, it strikes me as utterly ridiculous that this could happen.

I mean, Lord Kelvin had managed to work out that the Earth was at least 20 million years old 150 years ago. And that was before geology caught on as a pastime, let alone a serious area for research, pushing that age up to 4.54 billion years. Hell, even a rudimentary measurement of the thickness of the sedimentary pile we see preserved in crustal rocks, and a simple bit of calculation on settling rates puts you in the hundreds of millions of years. How can we possibly take ourselves seriously as a society if we let this 5000 year nonsense get promoted alongside actual, measurable, quantifiable, testable science?

It’s bad enough when private enterprises like ‘Creationism Museums‘ get set up. For such a large charity, with so much influence in this country to adopt this stance is truly terrifying. I can only presume that we can expect National Trust volunteers to shortly start providing alternative explanations of Stone Age archaeology, and placing some insightful dioramas of men in robes riding pleisiosaurs at strategic locations around Dorset. I’m really looking forward to the explanation of the Kimmeridge Bay ammonites as some kind of mass death-assemblage in a pan-global mega-flood a couple of thousand years ago.

To let a small local lobbying group have this much sway on a visitor centre for one of the most stunning geological sites in the UK is farcical – particularly after years of time to think about it. This appears to be an impolitic view in some circles, but just because you should respect someones *right* to an opinion doesn’t mean you have to actually heed their opinion. If I’m interested in how a computer works, and I get two conflicting opinions from an IT engineer and an astrologer who’s never used one, it doesn’t mean I conclude there’s still some debate on the subject.

The National Trust should be ashamed of themselves.

McLympics 2012

(Apologies for no science – normal service will resume shortly. Spleen needed venting)

To be fair, I should have caught the early warning signs when they released the official mascots. Stopcock and Vaudeville or whatever the hell they’re called. The most uninspiring, crappy, and useless mascots I’ve ever seen for anything. Primary schools around the country have done better jobs of creating engaging corporate personalities. The tragedy here is that one of the UK’s most successful cultural exports over the decades has been cartoons and characters.

And of course, we can’t forget the logo fiasco. The day it was published b3ta.com hosted two things that have stayed with me.  First, they Photoshopped a new logo in a goatse* theme which not only looked better than the official one, but even got onto the BBC as a ‘replacement submission from a child’.

The second thing they did is point out how much the official logo looks like Lisa Simpson giving head.  I literally have not been able to look at the logo once since that point without seeing it that way. So now you can all share that joy with me (assuming you weren’t already).

In fact, the first clue should have been when the highlight of the London presentation at the Beijing closing ceremony was a professional footballer - considering the olympics is an amateur competition.

That all should have been enough of a warning.

However, I can be an ignorant soul at times, and when I caught a whiff of the news that the esteemed institution at which I work was going to become an olympic village to host the rowers and flat-water kayakers, I was even a little bit excited. I’m a gullible fool.

Serious question – when was the last time you heard anyone talk about the olympics in terms of actual sport? The entire thing appears to have become a massive corporate carnival of crap. I know 4 people who were nominated as torch-bearers in the ongoing marathon around the country. The torch relay itself is a lovely idea, as is the idea that it gets within range of so much of the population. What is less great is that the procession basically consists of a whole load of huge buses with corporate advertising on, one person going along with a torch, then another queue of advertising buses. With a load of tannoy broadcasts trying to get people ‘excited’. Oh, and why in buggeration did Will.I.Am get a go on it? He doesn’t strike me as a Somerset local, so I can only presume that his sponsors couldn’t find a single other appropriate member of the UK population. Either that, or it’s a massive advertising scheme dressed up as a relay…

But that’s just endemic of a whole corporate whoring extravaganza. Have you read about the brand exclusion zones around all the sports areas? Presumably you also already know that the only branded food being sold inside the olympic parks are McDonalds, Coca Cola and Cadbury’s Chocolate?

But it’s not even just the companies. The branding madness goes far further. A quick peruse of the official branding document makes it eminently clear that the phrase ‘summer 2012′ is a protected term.  Which presumably is why it hasn’t bothered turning up here in the UK.

Not content with ruining our weather, they’ve gone to all sorts of extraordinary lengths to be a bunch of dicks about it. How about the town that was forced to rename an annual musical olympics? And of course the O2 Arena can’t possibly be allowed. They even consider puns fair game for censure – the idea to call a hog roast the the ‘Olympig’ was inspired.

I’m also really looking forward to seeing how their policing of this little gem will go down.  No photos or video footage to be taken inside the stadia.

There were some genuinely good ideas for some of the celebrations, but even these seem to get stymied. My favourite (and the only one I might have had any real interest in going to see) was the sailing of a trireme down the Thames. That got booted from the schedule just a couple of months ago.

Between all of that, the missiles, olympic lanes, ticket sales debacle, cost, and nonsense, I’ve had about enough.

I’m not even going to go into the massive ballache that working on campus has become now that LOCOG have got their greasy mitts (barriers, fences, patrols, security checkpoints, no-go-areas, et al.) all over it. Suffice to say remote desktopping and mobile phones are a wonderful thing. I certainly have no intention of struggling my way in and trying to find anywhere to park so I can come and watch the Coca Cola bus queue come past for the torch relay next week.

So apart from a bit of a whinge, what was the point of this post? Basically to voice my considered opinion that this Olympics is nothing but a huge misadventure in corporate douchebaggery. “The People’s Games” my arse.

Not once in this article have I mentioned sport, which at least puts me on a par with the way the entire event seems to have been organised. To close, I have only one thing to say, and I don’t *think* the following falls foul of the branding document:

“2012 sucks”.

* Do NOT google what goatse is if you don’t already know. Have a look at the wiki if you must, but don’t say I didn’t warn you. Suffice to say it is a horrific image which made something of a meme of itself over 10 years ago

Diamond Geyser – anatomy of a kimberlite eruption

Sorry, I can’t resist a pun.

Kimberlite pipes are – geologically and economically – hugely important things. These weird  features appear on maps as simple circular(ish) structures, perhaps up to a few hundred meters across. They are the vent which once supplied a volcano. More importantly, they’re stuffed full* of diamonds.

Excavation of several kimberlite pipes for diamonds, EKATI Mine, Canada. Image from Wikipedia

There’s a number of odd things about kimberlite pipes. Firstly, they are – on the most part – very old. We’ve never seen a kimberlite eruption take place, and they’re not particularly common in the geological past. There have been a few spurts of kimberlitic activity, and periods with none at all. Chemically, they’re very odd indeed. They can be broadly separated into two categories – both ultramafic, but Group 1 kimberlites are CO2 rich potassic, and Group 2 being ultrapotassic (3 times more potassium than sodium) peralkaline (so much potassium and sodium it can’t all go into feldspar minerals as the magma runs out of aluminium).

The source regions for these magmas is also an intereting – and contentious – issue. They’re derived from the mantle (>100 km depth), and make their way through the crust at very high speed (for a magma). The eruptions appear to be fairly explosive, as the pipes we observe often carry pyroclastic materials which fell back into the vent. Due to the general age, and ultramafic nature of these volcanoes, there’s not often** been any of the original volcanic edifice to analyse – all we have left is the sub-surface vent.

The reason for this post is that this week sees the publication of some work I’ve seen presented a couple of times in the last year or so looking at the Igwisi Hills kimberlite volcanoes in Tanzania. These are the youngest known kimberlite volcanoes in the world (Upper Pleistocene/Holocene, 100 – 120 ka). Because they’re so young, they have the surface eruptive structures still preserved.  These are able to give us a huge amount of information on how these volcanoes behave.

Prior to the recent study, the Igwisi Hills had only been looked at a couple of times by geologists –  most recently in 1966. They’re remote, very low elevation (standing no more than 40 m from the surrounding topography), and generally pretty underwhelming if you don’t know what you’re looking at.

The three vents all demonstrate the explosive eruption style which was assumed from the study of older pipes, but also bear lava flow activity which fills the scoria cone / Maar-like  pyroclastic craters. Over a period of a few days to weeks each of these cones formed, developed and finally grew silent.

The bulk of the paper deals with some very careful mapping and logging used to calculate relatively small eruption volumes (~10^5 m^3), and it’s the record of the eruption style and duration of these vents which is valuable. Kimberlite lavas are incredibly rare – now there is perhaps an indication that this is due to the lack of surface preservation, rather than a lack of formation.

To finally have a proper hold of what these volcanoes were doing at the surface is fantastic. however, there’s still a lot of questions unanswered, and if anything,  a whole truckload of new questions to ask. We still don’t know how these magmas form, or why they can be so diamond rich. We don’t now why they appear to form such discrete single pulses of activity.

This paper is a beautiful example of how there is still great fieldwork and science to be done even at the surface of our planet.  There’s another message it has too I think; after all, if this kimberlite had been one of those laden with diamonds I sincerely doubt we would still have such a pristine site to go and investigate today.

The paper can be found here:

Richard J. Brown, S. Manya, I. Buisman, G. Fontana, M. Field, C. Mac Niocaill, R. S. J. Sparks and F. M. Stuart, 2012. Eruption of kimberlite magmas: physical volcanology, geomorphology and age of the youngest kimberlitic volcanoes known on earth (the Upper Pleistocene/Holocene Igwisi Hills volcanoes, Tanzania). Bulletin of Volcanology

*Well, maybe 10-15 carats for every 100 tons of rock. A hundred tons of kimberlite would fill about 40 cubic meters, so an olympic sized swimming pool might be expected to have as much as 100 carats (20 g) of diamond in it

**A good paper demonstrating kimberlite pyroclastic density currents was kindly brought to my attention by a colleague who has a near encyclopedic knowledge of the literature.

Accretionary Wedge #46 – Geology, Life and Civilisation

For those of you who may not be aware, there is a fantastic thing in the geobloggosphere known as The Accretionary Wedge.  Every month or so,  someone hosts a specific topic.  Geobloggers are invited to contribute, and the submissions over that month are then collated on the hosts blog.

I’ve been meaning to join in for a while, but never quite got there for one reason or another.  This month it’s happening.

The topic, hosted over at Knowledge-flocs, is the relationship between Geology, life and civilisation. Or, in the words of Cat herself:

How has life or civilisation been affected by geology or how has geology been affected by life?

There are, within the field of geology, so many examples of this that it is difficult to pick any one.  Everything about our society has in some what been influenced by geology, whether a single event such as a devastating earthquake, to the economic wealth of particular areas driven by events in the geological past, through to migration patterns being impacted by mountains, oceans and rivers – all constrained by geological events and behaviours.

The one that occurred to me immediately, however is a a single, one-off event.  Had it not happened almost exactly where it did, at exactly the time it did (at least on a geological time scale), the world now would almost certainly be a completely different place.

To set the scene, we first must consider that much of world history for the last 2000 years has been dominated by European nations. Global colonisation (actually, mostly recolonisation) was driven by the great European powers throughout the Age of Exploration. This, after centuries of pan-European infighting, invasion, and intrigue.

These European powerhouses all grew from a similar background, with a long history of pan-continental trade and communication.  Much of this grew off the back of the Roman conquest of Europe, which in turn owed much to the Greek civilisation.

So how did we get to a point with such dominant European city-states, which could lead to the Roman Empire? Let’s go back in time a bit.

Prior to the Iron Age we largely have disparate local communities, with limited trade and communication. Through the Bronze Age (~3200 – 600 BC) we see a much more complex set of civilisations develop. Farming becomes well developed, allowing cities to flourish. We city-state civilisations develop in Africa, the Mediterranean, and the Persian plateau.

These states build on pre-existing trade routes, which in turn enables strong civilisations to grow in wealth, power and influence. We start to see the development of kingdoms, and from there our early European history takes shape.

So how does all of this relate to a geological event? Well, at some point between 1627 and 1600 BC, the volcano of Santorini erupted.

The eruption itself was significant, ejecting about 60 cubic kilometers of magma into the Aegean skies in a period of perhaps a few days. As that magma was jetted from the chamber, the dissolved gases within it came out of solution allowing the otherwise glassy shards to bubble into pumice, bulking the total volume of ejected tephra to about 100 cubic kilometers. That puts the eruption at about 4 times the volume of Krakatau in 1883, and makes it the fourth largest eruption in recorded human history.

That in itself is significant, but we’re still basing our history on the success of the Greek and Roman empires – what effect did this eruption have?

What the Santorini eruption did is completely devastate the Minoan civilisation. Based on the island of Crete, the Minoans were a remarkably advanced civilisation.  Their cities had stone paving,  sewerage, and not only were their buildings multi-storey, but also display considerable earthquake resilience (not entirely surprising when you consider where they lived).

The Minoans operated one of the main trade networks across the Aegean, with routes connecting the Northern and Western Mediterranean with areas as remote as Kush and Afghanistan. They were instrumental in the tin trade, essential for the smelting of the Bronze which defined the age. They appear to have built almost their entire empire on the basis of trade. They developed complex written languages, and produced impressive works of art and architecture.

When Santorini erupted it put an end to the Minoan civilisation. The trade fleet is believed to have been wrecked by the resulting tsunami, and many of its port towns and cities destroyed. The tephra fallout is likely to have made the Aegean difficult if not impossible to navigate for weeks or months, and volcanic ash and pumice will have blanketed everything.

However, without the fall of this mighty trade empire, there might never have been the window of opportunity for the Greek – and subsequently Roman civilisations to grow. That’s not to say the Minoans would still be going strong today – the nature of civilisations is to rise and fall.  The question is whether under different pressures and timescales  - in an environment with so many different city-states looking for power and influence – an entirely different history might have developed.

Following the Santorini eruption, the Myceanean civilisation – more into war and conquest than the trade-reliant Minoans – started to exert their influence over the Aegean. After a few hundred years the Myceanean civilisation ground to a halt, and the city-states of Greece eventually formed the ancient Greek civilisation we are all familiar with.

So, I think it’s fair to say that without that one-off cataclysmic eruption, we almost certainly would not have seen the same pattern of growth and development in ancient Europe, which in turn could not have spawned the same nations across the continent for the next 3500 years, which in turn means I almost certainly wouldn’t be sat here typing this.

Poking sleeping lions

I can only assume that the mass of exam papers in the department has caused a time-dilation.  It’s the only possible reason I can come up with for the fact it’s June next week.

After the rush of #gradingjail starting so quickly after my return from EGU, a flurry of job applications, and a mad catch-up attempt on my actual research project, I’ve somehow found myself staring down the barrel of my last 3 months of employment at RHUL.

Geologically it’s been an interesting month.  In fact just in the last week or so we’ve had the farcical fartisaurs, the attempted sale of an (allegedly) stolen tyrannosaur, and a devastating earthquake in Italy.  And lets not forget the woman with the burning rocks in her pocket.

However, there’s another story which has my interest.  At the end of last week the Campi Flegrei Deep Drilling Project was given the go ahead.  This is a project which has been on the cards for a while, and at various times hit either financial or political stumbling blocks.  The premise is simple; drill a hole down into the Campi Flegrei caldera.

Campi Flegrei is a pretty impressive volcanic complex; it has, in the past, been responsible for some very large VEI 7 eruptions, and has been gradually inflating pretty much since we started monitoring it.  This, combined with the fact it is a short walk from Naples city centre (Population 3 million) makes it an object of obvious interest for observation.

Campi Flegrei. Lots of nested calderas, Naples just creeping in to shot at the top centre, Vesuvius just out of shot to the top-right. Image taken from Google Earth.

I’ve been fortunate to spend some time around Campi Flegrei (and in fact camp within it), and it’s an impressive feature – mostly because you can hardly get any feel for its scale or structure from standing on to of it.  As a caldera volcano there’s very modest relief, and once you’re inside one crater, you can’t see any of the others.  Aerial and satellite views are the only way to get a decent feeling for the place.

The deep drilling project was originally scheduled to begin in 2008, but there was a degree of concern voiced by a number of geologists, and the local populace more widely.  With plans to put a 500 m test hole in, followed by a main drilling campaign down to 4km, there were concerns raised about high-pressure fluids, and – it being a volcano – a degree of panic about triggering an eruption.

In fact, the drilling project has no plans to penetrate the magma chamber, and while high pressure fluids may be present, there are high pressure fluids present in all deep-drilling projects.  Many countries have drilled near magma bodies in order to tap geothermal energy, so we’re not working completely in the dark.  Drilling into the magma body itself would be rendered largely untenable in any case, as the high temperatures as you approach the body wreaks havoc with drill heads.

There’s potentially a lot of information to be gathered from this enterprise – not just in better understanding the structure of the material lying above the magma chamber, but also in instrumenting the volcano to better measure the deformation and inflation of the magma chamber. The inflation (and deflation) of Campi Flegrei over the last few decades has been both intermittent and extensive.  There are Roman ruins at Pozzuoli which were built at or above sea level, which now have marks of marine shellfish burrows up to 7 m high on the columns. Those columns are now several meters above sea level.  Furthermore, in the four years between 1968 and 1972 Pozzuoli rose more than 1.2 m.  Something is going on in the magma system below, and properly instrumenting it is a useful step in better understanding it.

Of course, all this extra monitoring may be a completely pointless endeavor.  By far the biggest hazard Naples has to contend with – and one it might actually be able to do something about – is the utterly dreadful prognosis for evacuation.  As pointed out by the volcanocafe blog last month, the political infighting, public attitude toward volcanic risk, and the infrastructure make any hope of a successful mass evacuation into a pipedream.  Last year in Nature Warner Marzocchi, a geologist at the National Institute for Geophysics and Volcanology (INGV) in Rome stated that a complete evacuation of Naples’ 3 million residents “would be impossible to manage”.

Which may explain why they’re a little edgy about poking the lion sleeping next to them.

Viennese Whirl – EGU 2012

Thought it might be time for a little update on how EGU’s been going for those of you who couldn’t make it (and a restaurant tip below for those who could).

There’s been some really good science on show, and while the inevitable timetable clashes have been highly frustrating, between a bit of rushing around and planning with others everything has just about fallen into place.  Obviously this is only really going to represent what I saw (there’s 20-30 concurrent sessions all day, every day).

My particular interests have been pretty well served so far, although the physical volcanology is a little thin on the ground, and the turbidity current stuff later in the week also looks a bit sparse.

There were a couple of sessions on natural hazard modelling, and volcanic vent and eruption dynamics on Monday (run concurrently… grrr….), in which some really lovely examples of probabilistic hazard mapping and conditional frequency mapping (something I’m applying to my own work on turbidites at the moment) were given.  There were also presentations on VolcWorks and vHub – both collaborative works to bring wider access to modelling suites such as Titan2D, Tephra2 and similar.  While VolcWorks is aimed at observatory workers wanting straightforward modelling and mapping workflows, vHub is being targetted more at the research and teaching end of things.  Looks like they have huge potential.

Yesterday for me was dominated by the ‘Physics and Dynamics of magma ascent, emplacement, and deposition in volcanic systems’ session – something of a mammoth which was born of several smaller sessions (including the one I had been co-chairing) which ended up merged.  It actually worked out really nicely, as the flow was retained with talks presented in a logical order.

Perhaps the most interesting talk of the day was by Ed Llewellin  (Durham, UK) who presented some really nice work on the effects of crystal shape on magma viscosity.  Coming from a granular modelling background myself it was an interesting demonstration that things known in one field are not necessarily well considered in others.  The presentation made a convincing case that increasing aspect ratios of crystals in magmas can cause 10-fold increases in bulk viscosity compared to assumed spherical crystals.  That obviously has huge implications for eruption dynamics assumptions, and with the mineral dependence of crystal shape, presumably we’re going to see a tranche of work on this in the future looking at the effects of different magma chemistries and cooling histories on crystal shape-derived viscosity changes.

I think my favourite find of the day, however, was down in the basement poster halls, where adjacent posters by Steffi Burchardt and Val Troll (both of Uppsala University, Sweden) presented the analyses of the ‘restingolites’ formed in the El Hierro eruption of 2011.  I covered these eruptions in some detail, and briefly mentioned these funny old blocks last year, which were found floating to the surface at the ‘jacuzzi’ – a hot pool above the active submarine vent.  They have a number of notable features – They have a dark basaltic crust, but highly vesicular folded white internal structure.  There’s a collection of photos of some of these things here.

The two-tone folded structures are weird.  The striking two-tone nature (indicating two very separate rock types) is weird.  It turns out that things get far, far weirder.

These restingolites contain fossils.

The white material is Cretaceous sediment containing marine microfossils.  The Hierro activity was fed by a high-level magma chamber injected at the base of the sediment pile.  Fragments of this sediment inevitably found themselves sinking within this basaltic magma.  Troll and his many and various co-workers have modelled the process and found that after 10 days of submersion in basaltic melt,  these enclaves of sediment had outgassed and vesiculated enough to become buoyant within the chamber and rise to the top, before being erupted.  Hence you get a vesiculated high-temperature metasediment containing microfossils, mingling textures, and surrounded by a basaltic crust. Awesome.

Fossil bearing pumice material is a first for me, and now I desperately want to get hold of some as a teaching sample.

There’s more info and pictures available here and no doubt more to come in the future.

In non-conference related news the Vienna Natural History Museum is great, with a beautifully presented and impressive mineral collection.  Found some lovely little restaurants and bars serving the beer, sauerkraut, sausages, stews and dumplings we all love, but these were somewhat put in the dark by last nights visit to the Schweizenhaus in Prata.  After a slightly creepy walk through the empty carnival grounds, we were greeted with a place specialising in roast pork and Czech beer.  I would wax lyrical, but I think this picture probably does it justice.  If you’re in Vienna at any time I highly recommend it.