Monthly archives of “August 2014

comment 0

Really Old Mongolian Limestone

There’s an awful lot of limestone in Mongolia. When you are in your Landcruiser lurching your way along the rocky tracks of the Gobi Altai you can spot whole mountains of the stuff off on the horizon. White mountains, or near enough to white. When I first started geological mapping  in the region I was intrigued by the stuff. Partly this was because I was hoping it would be full of fossils. Much later I would come across fossil-rich limestone, but where I first worked, the limestone was a bit recrystalised (technically some of it might be marble). This tends to obliterate fossils. The other reason it was intriguing was its great age – it was variously listed on the Soviet/Mongolian geological maps as “Vendian” or “Cambrian” in age. Vendian is latest Precambrian and the Cambrian is immediately after that – the earliest period from which hard, shelly fossils are known (Some might call it the age of trilobites). What I didnt know at the time was that Vendian is mostly not used by western geologists any more – having been superceded by the “Ediacaran”. It turns out that this was the result of a sort of geological coup where Australian geologists managed to get the type section for a roughly similar period of time officially recognised in their own country. But whatever name you want to go by – this time is well before coral reefs, so it got me wondering – what was it that actually formed these really old limestone massifs?

An outcrop of limestone in the Gobi Altai, Mongolia - known as the "White Doors".

An outcrop of limestone in the Gobi Altai, Mongolia – known as the “White Doors”.

A view of the limestone "White Doors" from the other side. Our Landcruiser gives the scale. We slept in swags between it and the limestone. Two times in the night I heard wolves howling high up in the mountains.

A view of the limestone “White Doors” from the other side. Our Landcruiser gives the scale. We slept in swags between it and the limestone. Two times in the night I heard wolves howling high up in the mountains.

The nearest town to my base was Gobi Altai. At first this could be done in about 45 minutes, straight over the mountain, if the weather was good, or a bit longer around the base. After a camp shift it became a good two hours away. Up behind Gobi Altai town is a limestone massif – and one day I had the chance to get there for a quick look. I picked up a chunk of limestone that, despite some recrystalisation, had nice fossils visible. These were archaeocyathids – the first reef-forming animals(according to Wikipedia). They are only known from the Early Cambrian, and yet diversified into over a hundred families. On the rock surface they can look like rings that are a centimeter or two in diameter. These are cross-sections of the organism, which the Wikipedia entry describes as “nested ice cream cones”. It is thought they are either a type of sponge, or something related to a sponge. In any case, huge accumulations of archaeocyathids might have formed some of those limestone massifs – but only the Cambrian ones.

Could the limestone have been formed by stromatolites? These were the first reef-forming organisms (Yes, I had to read it twice, Wikipedia states archaeocyathids were the first reef-forming animals). Stromatolites were formed by micro-organisms, especially cyanobacteria. They were common in the Precambrian (I’ve seen the limestone they built up in South African Precambrian sequences). Uchio et al. (2004) documented what they called “The oldest mid-oceanic carbonate buildup complex” from Vendian rocks in the Gorny Altai Mountains of Siberia. This location is several hundred km from the Gobi Altai (Yes, more than one Altai = ‘Golden’ mountain) but possibly a broadly similar group of rocks. Uchio et al. (2004) concluded their limestone had originally been no more than 500 m thick, and had accumulated on an undersea volcanic plateau. Preservation was good enough to see stromatolites and remains of other more enigmatic micro-organisms. However, much of the limestone was massive, and much of the thickness may have formed from lime mud, and Uchio et al. (2004) determined it could be considered as an ‘Agglutinated Microbial Reef’ sensu Riding (2002). He wrote that these “consist mainly of microbially trapped particulate sediment”. To me this sounds a bit like stromatolite, but without the lamina that are intrinsic to genuine stromatolites. In any case, the key component to identifying the Gobi Altai limestone as one of these is a direct association with volcanic rock – something which would, in the Mongolian case, have been metamorphosed to greenschist. This might have been the case, but with structural deformation and the fact that our job wasn’t to delve into such details, this wasn’t clear.

But there is yet a third possibility. It is now clear that there were several Precambrian glaciations of huge extent – big enough to warrant the term ‘Snowball Earth‘ (Hoffman & Schrag 2002).  Glacial sediments are typically overlain by 3-30 m of what has been called a “cap carbonate’. One explanation for their formation is that during such an extensive glaciation rocks are covered with ice, so normal weathering processes can’t operate. This means there is no sink for carbon dioxide, which continues to build up in the atmosphere from volcanic eruptions. Eventually the super-greenhouse conditions melt the ice, and the carbon dioxide quickly reacts with the exposed fresh rock  to form carbonate. One of these cap carbonate sequences is known from the Tien Shan Mountains of Xinjiang Province, China. This is not too far (a few hundred km) from the Gobi Altai. The key here is an association with glacial-formed rock such as a tillite. This is probably not possible in the Gobi Altai due to the amount of metamorphism.

These massive late Precambrian-Cambrian limestones are an integral part of Mongolian geology – they are one of the things you see a lot of in the field. They are ripe for some more detailed work to figure their origins.

References

Hoffman, P.F. & Schrag, D.P., 2002. The snowball Earth hypothesis: testing the limits of global change. Terra Nova 14, 129-155.

Riding, R. 2002: Structure and composition of organic reefs and carbonate mud mounds: concepts and categories. Earth-Science Reviews 58:  163 – 231.

Uchio, Y., Isozaki, Y., Ota, T., Utsunomiya, A., Buslov, M. M. & Maruyama, S. 2004: The oldest mid-oceanic carbonate buildup complex: Setting and lithofacies of the Vendian (Late Neoproterozoic) Baratal limestone in the Gorny Altai Mountains, Siberia. Proceedings of the Japan Academy Ser B Physical and Biological Sciences 80: 422-428.

comment 0

Sunday School stole my heritage – Bears, Baa-lambs, and Salmon

Don’t get me wrong – Christian virtues (the teachings of JC) are admirable. I was brought-up going to ‘Sunday School’ and I guess it didn’t do me any harm. I’m not exactly sure what I did get out of it – we were told ‘Bible stories’ and there was a fair amount of colouring-in pictures of the same. Pictures of shepherds with their flocks of goats and sheep in a bone-dry, rocky, treeless land (courtesy of said goats and sheep). Yes, I was brought up as a ‘Christian’, no particular problems there. But what I do feel kid of resentful about now – is that meant being brought up on what was essentially someone else’s heritage. Being of solid ‘Atlantic facade’ and far-north Scandinavian background, goats, sheep and Middle-eastern deserts really aren’t my roots. Where were the tales of the deep-forests that my ancestors lived-in? Tales of reindeer, lynx, wolf, beaver, and bear? Well, as for the bear, I now have a sort of explanation and I blame it entirely on the Otago University Book Shop (Dunedin). It’s invariably a fatal (for my wallet) decision to pop inside that place, but what I came across, I probably wouldn’t have spotted it on-line.

It was an odd kind of book – “The Bear – History of a Fallen King”, written by Michael Pastoureau, an Italian, and translated into English by George Holoch. It explains how the European church set out, quite deliberately, to destroy the bear. In pagan days it was the European ‘King of the Beasts’, an animal so strong, but at the same time, weirdly human-like. In days before DNA and rigorous comparative morphology – it was our closest relative. It featured in mythology, festivals, rituals, personal names and heraldry. But Saint Augustine declared “Ursus est diabolus (the bear is the Devil)” and it was all on. Over several centuries the Church made sure the mighty bear was first demonised, then  ridiculed. To achieve this the Church needed to replace the bear with something else – the lion. This is why, throughout almost all of Medieval European heraldry – you see heaps of lions, but no bears. By this time, the destruction of the bear’s reputation was complete. Total elimination of the bear would take a bit longer. Pastoureau’s verdict, after 239 pages – is grim:

“In killing the bear, his kinsman, his fellow creature, his first god, man long ago killed his own memory and more or less symbolically killed himself. It is too late to turn back the clock. … conservation measures … seem totally futile … the bear is doomed to disappear”. 

So my myths were replaced by sheep and goats and my pageantry by lions – none of these are European. Yes, I feel robbed. But the book got me wondering – where are the bears in Irish/Scottish mythology? Actually they don’t seem to crop up much, other than incidental cameos. When it came to the really important spiritual beings – the Irish, as you might expect, were a little less predictable. The oldest and wisest creature in the ancient Irish world was a … salmon.

The reason it was wise is because it lived in a pool where it ate some very special hazelnuts that dropped in. Weirdly, the fate of the salmon was to be eaten. To me this sort-of smacks of one of those instances where a conquering religion manipulates the local mythology to establish a new status-quo. As in: “forget your salmon guys, our chaps grilled it”. But other versions of the tale suggested the right kind of fish+hazelnuts would come along every seven years. Perhaps it would be a bit too logical to suggest somebody should have just looked after that grove of hazel-trees.

The position of the salmon in Irish mythology is actually, not so silly when you think about it. Salmon were/are incredibly important in the lives of many northern cultures and they figure prominently in myths. The one or two Irish stories that we have may be all that survived of a much earlier veneration of that fish.

Bears, salmon, hazelnuts – am I seeing the shadows of my culture’s myths?

comment 0

New Zealand, Middle-earth and Reality

There was a time when I threatened myself to start teaching the ecology of Middle-earth. I helped take a couple of trips taking American university students around New Zealand. It was an amazing itinerary, but it came with a strong feeling that my students were far more interested in where scenes from ‘Lord of the Rings’ were filmed than in actual, real-life ecology of New Zealand. Yeah, I was ready to give in, to go with the flow. ‘Lord of the Rings’ did a lot for New Zealand tourism, I’ll grant it that. It had some other effects too, so I understand. It brought us so far on to the radar that cashed-up foreigners snapped up some prime real-estate. Sour grapes? Yeah, I’m uncomfortable about it. Now New Zealand is going hell for leather to make the most of its new-found Middle-earth image. It has become Middle-earth, and what could possibly be wrong with that?

So what is it about Middle Earth that is so appealing? My guess is it’s not just the spectacular scenery – it’s somehow incorporated the sense of pre-industrial lifestyle. Well, at at least above ground – the industrial heartland seems to be nicely out of sight below the Misty Mountains (I’m not a Tolkien-freak, so I’m bound to get some names and geographies wrong). where all the dwarves are mining. I’m not sure where their intensive on-surface agricultural base is and surely the degree of smelting associated with all that mining will have caused massive deforestation, acid rain, polluted air, polluted rivers,  …. but that would spoil the image. I would guess that there was also the appeal of a land with a sense of mystery – a place where there was ‘wilderness’ and where ‘adventure’ was possible. And if you focus on what could be considered the ‘core’ of Middle-earth, at least from Tolkien’s point of view – The Shire, it’s extremely egalitarian.

But what is the reality that our tourists see? The movie scenery, absent a few digital additions, is all too real. New Zealand/Middle-earth is a pretty country. Within a short drive/walk/cycle you can see forest, mountains, fords, glaciers. I can even accept that some people see grassy cow paddocks in front of snowy mountains as ‘pretty’. What they don’t see is what there isn’t there to see, because it’s gone -the massive number of species that are extinct or near-enough so. And you would need a little education to tell a healthy forest from one that’s being eaten alive by cows, deer or possums. But look beyond the landscape to the social environment. I see on the National Party’s website “New Zealanders know that this country today is doing better than most other developed countries … ” If your idea of “doing better” is limited to a weird abstract entity called … The Economy.

When I was a kid we all understood that New Zealand was ‘egalitarian’. And it was something to be proud of. I remember being told (I would say late 1960s) that we probably did have millionaires – but they kept themselves quiet. How things have changed!  I’ve just finished ‘The Spirit Level‘, a book documenting, very bluntly, the relationship between increasing inequality in developed countries – and a whole range of social dysfunction. We’re talking obesity, mental illness, imprisonment levels, life-expectancy, teen pregnancies, trust, and a bunch of other things. Sound familiar? The shocking thing to a kiwi of my generation is to learn that New Zealand is now at about number three globally for all these things (hardly better than “most other developed countries”). It’s happened over the last 30 years or so, as we went from being that egalitarian society to one of the most unegalitarian.

As The Spirit Level points out, again and again, ‘egalitarian’ doesn’t just mean improvements for the lower ‘class’ in society. And it doesn’t mean we have to become communist, tree-hugging hippies, intent on destroying capitalism. It means that a reduction in levels of inequality – independent of how they are achieved, will benefit all of us. Yep, even in the upper echelons of society, life expectancy will increase. Incarceration levels will decline, meaning we can spend more money on  education instead of prisons. It will even mean we get more time off. It’s not fantasy, because there are societies whether this have been achieved – Sweden being the classic.

But don’t take my word for it, read the book. Or if you want a quick introduction, check out a You-Tube video. The authors also have a website. There are of course, other points of view. I haven’t yet read that one, but judging from the reviews, I don’t expect much.  We (New Zealand)are heading for an election soon – but few parties emphasise policies to lower the inequality levels that will result in a better place for us all to live in (Flicking through party websites I see a lot of projects, not policies).

For a tiny, beautiful country with a population of less than 4 million – there simply isn’t any excuse to not be Middle-earth.