barely on topic due to proximity of many North American precious metals mining operations - AND a real treat for every geology buff from the USGS:
Prize exchange:
Supervolcanoes
BBC2 9:30pm Thursday 3rd February 2000
NARRATOR (SINĀAD CUSACK): Yellowstone is America's first and most famous National Park. Every year over 3 million tourists visit this stunning wilderness, but beneath its hot springs and lush forests lies a monster of which the public is ignorant.
PROF. ROBERT CHRISTIANSEN (US Geological Survey): Millions of people come to Yellowstone every year to see the marvellous scenery and the wildlife and all and yet it's clear that, that very few of them really understand that they're here on a sleeping giant.
NARRATOR: If this giant were to stir, the United States would be devastated and the world would be plunged into a catastrophe which could push humanity to the brink of extinction.
PROF. ROBERT SMITH (University of Utah): It would be extremely devastating on a scale that we've probably never even thought about.
PROF. BILL McGUIRE (Benfield Greig Centre, UCL): It would mean absolute catastrophe for North America and the problem is we know so little about these phenomena.
NARRATOR: In 1971 heavy rain fell across much of east Nebraska. In the summer palaeontologist Mike Voorhies travelled to the farmland around the mid-west town of Orchard. What he was to discover exceeded his wildest dreams.
PROF. MIKE VOORHIES (University of Nebraska): Well I was walking up this gully looking for fossils, the way I'd walked up a thousand gullies before, keeping my eye on the ground looking for pieces of fossils that might have washed down in the rain the previous night and I scrambled up to the top and I saw something that completely astounded me, a sight that no palaeontologist has ever seen.
NARRATOR: It was a sight of sudden, prehistoric disaster. Voorhies's digging revealed the bones of 200 fossilised rhinos, together with the prehistoric skeletons of camels and lizards, horses and turtles. Dating showed they had all died abruptly 10 million years ago.
MIKE VOORHIES: It suddenly dawned on me that this was a scene of a mass catastrophe of a type that I'd never, never encountered before.
NARRATOR: The cause of death, however, remained a mystery. It was not from old age.
MIKE VOORHIES: I could tell by looking at the teeth that these animals had died in their prime. What was astounding was that here were young mothers and their, and their babies, big bull rhinos in the prime of life and here they were dead for no, no apparent reason.
NARRATOR: For the animals at Orchard death had come suddenly. There was another strange feature to the skeletons, an oddity which offered a crucial clue about the cause of the catastrophe.
MIKE VOORHIES: We saw that all of these skeletons were covered with very peculiar growth, soft material that I first thought was a mineral deposit. Then we noticed that it was cellular. It's biological in origin so there was something actually growing on those bones. I had no idea what that stuff was, never seen anything like it.
NARRATOR: A palaeo-pathologist, Karl Reinhard, was sent a sample of the bones.
PROF. KARL REINHARD (University of Nebraska): This specimen is typical of the rhino bones. You see this material, in this case it's a whitish material that's deposited on the surface of the original bone. This is peculiar to me, but as I thought back in my experience I realised that this was similar to something that turns up in the veterinary world, a disease called Marie's disease.
NARRATOR: Marie's is a symptom of deadly lung disease. Every animal at Orchard seemed to be infected.
KARL REINHARD: One of the clues was that all of the animals had it. Now that is a very important observation for all the diseases, all the animals to exhibit this disease there had to be some universal problem.
NARRATOR: Scientists discovered the universal problem was ash. 10 million years ago ash had choked them to death.
KARL REINHARD: It may have been a bit like pneumonia with the lungs filling with fluid, except in this case the fluid would have been blood for the ash is very sharp. There'd be microscopic shards of ash lacerating the lung tissue and, and causing the bleeding. I would imagine these animals as stumbling around the thick ash, spitting up blood through their mouths and gradually dying in a most miserable way.
NARRATOR: Only a volcano could have produced so much ash, yet the wide flat plains of Nebraska have no volcanoes.
MIKE VOORHIES: I remember some of my students and I sitting around after a day's digging and just speculating where did this stuff come from? There, there are no volcanoes in Nebraska now. As far as we know there never have been. We, we obviously had to have volcano somewhere that, that produced enough ash to completely drown the landscape here, but where that was really was anybody's guess.
NARRATOR: One geologist in Idaho realised there had been a volcanic eruption which coincided with the disaster at Orchard 10 million years ago, but the site was halfway across North America.
PROF. BILL BONNICHSEN (Idaho Geological Survey): It seemed like a really fascinating story which made me think, because I had been working on volcanic rocks in south-western Idaho that potentially could make lots of ash and, and there was some age dates on that that were around 10 million years and I began to wonder wow, could this situation in Nebraska have really been caused by some of these large eruptions that evidently had happened in south-western Idaho.
NARRATOR: The extinct volcanic area, Bruneau Jarbridge, was 1600 kilometres away, a vast distance. How could this eruption have blasted so much ash so far? Bonnichsen was sceptical.
BILL BONNICHSEN: Volcanoes will spew ash for a few tens or maybe a few hundreds of miles. This ash, and it's like two metres thick, in Nebraska is 1600 kilometres or more away from its potential source, so that's an amazing thing. There really had been no previous documentation, to my knowledge, of phenomenon like that.
NARRATOR: Despite his doubts Bonnichsen decided to compare the chemical content of ash from the two sites. He analysed samples from both Bruneau Jarbridge and Orchard and plotted their mineral composition on a graph looking for similarities.
BILL BONNICHSEN: if you have a group of rocks that are very similar to one another they should be a closely spaced cluster of pods. We had these analyses come out from the Orchard site and I thought I'd try the clock again and see how close they were to one another. By golly, they fall right in the same little trend as the Bruneau Jarbridge samples.
NARRATOR: Bonnichsen's hunch had proved correct. Bruneau Jarbridge was responsible for the catastrophe at Orchard. An eruption covering half of North America with two metres of ash was hundreds of times more powerful than any normal volcano. It seemed almost unbelievable, but then Bruneau Jarbridge was that rarest of phenomena which scientists barely understand and the public knows nothing about: a supervolcano.
ROBERT SMITH: Supervolcanoes are eruptions and explosions of catastrophic proportions.
BILL McGUIRE: When you actually sit down and think about these things they are absolutely apocalyptic in scale.
PROF. MICHAEL RAMPINO (New York University): It's difficult to conceive of a, of an eruption this big.
NARRATOR: Scientists have never witnessed a supervolcanic eruption, but they can calculate how vast they are.
Last few exchanges include(but all is a very interesting read):
NARRATOR: This team of scientists believe the bottleneck occurred between 70 and 80,000 years ago, although this date is hotly debated. Toba erupted in the middle of this period, 74,000 years ago. If there really is a connection this research has terrifying implications for a future Yellowstone eruption. It could well be of a similar size and ferocity to Toba. Like Toba, it would have a devastating impact, not just on the surrounding region, North America, but on the whole world.
MICHAEL RAMPINO: If Yellowstone goes off again, and it will, it'll be disastrous for the United States and eventually for the whole world.
NARRATOR: Vulcanologists believe it would all start with the magma chamber becoming unstable.
BILL McGUIRE: You'd start seeing bigger earthquakes, you may see parts of Yellowstone uplifting as magma intrudes and gets nearer and nearer the surface.
ROBERT SMITH: And maybe an earthquake sends a rupture through the brittle layer, you've broken the lid of the pressure cooker.
BILL McGUIRE: This would generate sheets of magma which will be probably rising up to 30, 40, 50 kilometres sending gigantic amounts of debris into the atmosphere.
ROBERT CHRISTIANSEN: Where we are right now would be gone. We would be instantly incinerated.
MICHAEL RAMPINO: Pyroclastic flows will cover that whole region, maybe kill tens of thousands of people in the surrounding area.
BILL McGUIRE: You're getting a, an eruption which we can barely imagine. We've never seen this sort of thing. You wouldn't be able to get within 1,000 kilometres of it when it was going like this.
ROBERT CHRISTIANSEN: The ash carried in the atmosphere and deposited over large areas of the United States, particularly over the great plains, would have devastating effects.
BILL McGUIRE: The area that would be affected is, is the bread basket of North America in effect and it produces an enormous amount of grain on a global scale really. That's, that's, that's the problem and you would see nothing. The harvest would vanish virtually overnight.
ROBERT CHRISTIANSEN: All basic economic activity would certainly be impacted by this and let alone changes in the climate that could possibly be induced.
MICHAEL RAMPINO: The climatic effects globally from that eruption will be produced by the plume of material that goes up into the atmosphere. That'll spread worldwide and will have a cooling effect that will probably knock out the growing season on a global basis. We can't really overstate the effect of these huge eruptions. Civilisation will start to creak at the seams in a sense.
ROBERT SMITH: The fact that we haven't seen one in historic time or documented means the human race really is not attuned to these things because they're such a rare event.
MICHAEL RAMPINO: It's really not a question of if it'll go off, it's a question of when because sooner or later one of these large super eruptions will happen.
presented for consideration
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casual readers should note: these are far from your garden variety TEOTWAWKI NUTS, This is a BBC report, which speaks with top professors from ID, NE, NY and respected members of the USGS.
Presented For those making an investment in land or mining for as much the next generation as your own. |
