There’s a real mix of topics on offer in this week’s geoscience round-up, and plenty more that I had to leave out — though, the world being the place it is and research science being an incremental process, I daresay those particular areas will be back on my list before very long. So this week we have a couple of very different approaches to historic volcanism, something extra-terrestrial, and a monster or two.
Iceland’s Eldgjá Eruption and the Coming of Christianity
I was particularly interested to see a paper published this week in the journal Climatic Change which happened to pick up on several of my areas of particular personal interests — volcanism in Iceland, how we understand what happened before scientific recording, and the interaction of the Earth system and the culture of the humans who live upon it.
Let’s begin with the volcanoes. Iceland’s tectonic setting has blessed (or cursed) it with a wide range of volcanic types, and one of the longer-lived and most spectacular is the effusive eruptions like that of Bárðarbunga back in 2014-5. Such eruptions can last for years and, without causing too much of an immediate impact, produce enormous volumes of ash and spectacular fireworks displayed.
One of the most notorious eruptions is that of the Eldgjá fissure system, part of Katla volcano, in the middle of the tenth century, not long after the settlement of Iceland. The Global Volcanism Program gives its date as “0934 ± 2 years-0940 (?)” which just about sums up what we know about it — until now.
This week, new research has narrowed the date down much more specifically, using tree ring data and volcanic ash preserved in ice cores from Greenland to fix the onset of the eruption to early 939 and its earliest conclusion to autumn the following year.
This is where the humans come in. There’s ample evidence that cataclysmic events have had an impact on human thinking — by no means the least of them being another Icelandic fissure eruption, Laki, which is credited with having caused food shortages which exacerbated a difficult political situation and helped to cause the French Revolution.
Contemporary written sources make reference to the eruption and its environmental impacts, but perhaps the most fascinating part of the research is the suggestion that the eruption was interpreted by some as the anger of the pagan gods and that it “acted as a catalyst for the profound cultural change brought about by conversion to Christianity”.
I would love to go into all aspects of this particular study in much more detail — and, indeed, spend time following up the references, but for now I’ll leave it at that. If you’re interested, the study is open access and listed in the references. And, for the record, it’s probably one of the most fascinating research pieces I’ve read this year.
I promised you an extra-terrestrial — and so, here’s Steve. If you’re interested in the aurora, you may have read about an unusual phenomenon which has been observed during episodes of the northern lights, namely pillar-like wisps of light which not only differ from the usual arching light show, but are different in colour and observed much further south than the ‘full’ aurora. Not knowing what it was, but knowing that it was different, aurora watchers named it Steve.
You would need to be a physicist, and probably an astrophysicist, to understand all the terminology. Put simply, the aurora is caused by charged particles from the sun reaching the Earth’s atmosphere, and, avoiding the technicalities, these pillar lights appear to be caused by variation in the temperature and density of these particles.
So what did the researchers call it? Well, they’ve taken on board the public vote and chosen the scientific acronym to fit it. “On the basis of the measured ion properties and original citizen science name, we propose to identify this … as a Strong Thermal Emission Velocity Enhancement (STEVE)”.
Can Volcanic Clouds Have a Silver Lining?
Volcanic supereruptions — those really, really large ones that have devastating impacts and send people into panic at the mere suggestion that one of them might occur — have had devastating impacts on the planet and its fauna. It’s beyond question that, were one to occur now, the damage would be almost inconceivable and the impact on the world’s climate significant.
They’re incredibly rare, the most recent to have occurred being that of Toba, in Indonesia, roughly 74,000 years ago. The eruption was huge: the GVP describes it as “the world’s largest known Quaternary eruption, ejecting about 2500-3000 km3 (dense rock equivalent) of ignimbrite and airfall ash,” and its impacts will have been significant.
The degree to which humans were impacted by the eruption is, however, up for debate. Five years ago the BBC was reporting on research which questioned the prevailing theory that the eruption might have brought humanity to the brink of extinction, and further research published this week takes this debate a step further.
Studying sites in Africa where volcanic ash from Toba has been found, researchers looked at the impact on human settlement. Far from finding it wiped out, they discovered evidence that it prospered. “After Toba, the intensity of population increased. People were in bigger groups at the site, or staying at the site for longer periods,” the BBC quotes a member of the research team as saying.
I said above that research is incremental and this is another example of a story that, as it unfolds, challenges the views we hold of the past, and therefore potentially the future, impacts of major events.
Footnote on Dinosaurs
I wish I loved dinosaurs more than I do. If I did, then I’d probably know far more about the iconic archaeopteryx. Nevertheless, I was fascinated by an article about these creatures which popped up on my news feed this week, if for no other reason than it tackles the same thorny problem that I’ve talked about above — namely, how we can establish what happened hundreds, thousands or in this case millions of years ago.
One of the big puzzles about archaeopteryx is whether or not it could fly. This time researchers have tried a different approach to learning about the past, by applying a variety of scientific techniques (with which, I confess, I’m not familiar) to a comparison of three archaeopteryx specimens.
Their conclusion? That the creatures: “actively employed wing flapping to take to the air”. So now you know.