The honey hunters

One of the things I learned from 32 years of teaching biology is that many non-human animals are way smarter than we give them credit for -- and its corollary, which is that we humans are not as far separated from the rest of the natural world as many of us would like to think.

A charming piece of research in Science this week illustrates this point brilliantly.  It's about a species of African bird, the Greater Honeyguide (its scientific name, which I swear I'm not making up, is Indicator indicator).  It's found in open woodland in most of sub-Saharan Africa, and has a very specialized diet -- it lives on bee eggs, larvae, and wax (it's one of the few known animals that can digest wax).

Illustration of a Greater Honeyguide by Nicolas Huet (1838) [Image is in the Public Domain]

Because of its diet, local residents have developed a mutualistic relationship with honeyguides, a relationship that is what gives the birds their common name.  People living in the region listen for the bird's call and then follow it to find the bees' nests it was attracted to.  The people tear open the nests and take the honey -- and the bird gets the larvae and the wax.  Many cultures that live in the honeyguides' range have developed specific calls to attract the birds when they're ready to go on a honey hunt.

The study, led by ecologist Claire Spottiswoode of the University of Cambridge, looked at the fact that honeyguides seem to learn the specific calls used by the people they live near.  Initially, it was uncertain if the people had figured out what the birds responded to, or if the reverse was true and the birds had learned what noises the people made.  So she and her team decided to test it; they used recordings of individuals from two cultures that are known to use honeyguides, the Hadza of Tanzania and the Yao of Malawi and Mozambique.  The Hadza employ a complex series of whistles to summon their helpers, while the Yao make a "brrr-huh" sound.

Both signals work just fine, but only in particular regions.  When a recording of the Hadza signal is played in Malawi, or a recording of the Yao signal is played in Tanzania, the birds don't respond.  The birds have evidently learned to recognize the specific calls of their partners in the region where they live -- and don't "speak the language" used elsewhere.

Spottiswoode's team also found there are two places where the symbiotic relationship is falling apart.  In more urban areas, where commercial sugar is widely available, there are fewer people engaged in honey hunting, so the birds have decided they're better off working as free agents.  Even more interesting, in some areas in Mozambique, the Yao discovered that if they destroy the wax and the rest of the hive, the honeyguides will stay hungry and look for other nests.  But... the birds are learning that their human partners are stiffing them, and they're becoming less likely to respond when called, so the human honey hunters are having less overall success.

So even birds can recognize when they're getting a raw deal, and put a stop to it.

The more we find out about the other life forms with which we share the planet, the more commonality we find.  Everything in the natural world exists on a continuum, from our physiology and our genetics to characteristics many thought of as solely human traits, like emotion, empathy, and intelligence.

So be careful when you throw around terms like "bird-brain" -- they're not as far off from us as you might like to believe.

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Geological toothpaste

One of the fun things about science is that sometimes, when you look closely at a phenomenon, you find out that what you thought was fairly simple turns out to be not only complex but just flat-out weird.  That was my reaction to something I first heard about only a couple of days ago, which (like the topic of yesterday's post) comes from the realm of geology.

Continental slopes are generally pretty straightforward.  They represent a sharp boundary between continental crust (usually thick, cold, and relatively old) and oceanic crust (by contrast, thin, hot, and fairly recent).  The slopes are steep dropoffs -- the topography of the ocean floor is no gradual decline down toward the abyss -- and the continental shelves, the shallow regions of varying widths that ring the continents, are actually geologically part of the continent.  (They just happen to be covered by sea water.)

So the continental slopes shouldn't be that complicated.  They're a narrow transitional band separating shallow regions connected to the continental land masses from the very different geological realm of the deep ocean.

But then there's the Sigsbee Escarpment.

The Sigsbee Escarpment is a stretch of the continental slope in the Gulf of Mexico, south of coastal Louisiana, Mississippi, Alabama, and Florida.  The first clue that there was something weird going on there is that the continental shelf north of it is a good bit wider than it should be -- certainly wider than a lot of continental shelf regions.  This is great for the fishing industry, which thrives in shallow continental shelf regions.  The deep ocean has far less in the way of life, largely due to the fact that the depth makes significant vertical mixing difficult, so nutrients that settle to the ocean floor tend to stay there.  Any given cubic meter of surface water over the deep ocean is unlikely to have much living in it beyond single-celled organisms.

Most continental shelves are relatively narrow, but the Sigsbee Escarpment sticks way out into the Gulf, and the reason why has to do with the combination of something that happened 150 million years ago and something that happened two thousand kilometers away.

[Image courtesy of Harry H. Roberts and the National Oceanic and Atmospheric Administration]

At the beginning of the Jurassic Period, around two hundred million years ago, North and South America were joined (well, everything had been joined not long before; Pangaea had lasted through most of the Triassic Period).  Rifting opened up what would eventually become the Gulf of Mexico, letting seawater into a new embayment that initially was quite shallow.  The climate was generally hot, so for the next fifty million years, the evaporation rate was high, and this water became extremely saline, leading to the deposition of huge quantities of crystalline salt on the seafloor.

These salt deposits are found all over the southeastern United States, and what are responsible for the Lake Peigneur disaster in November of 1980.  Lake Peigneur is a broad, brackish lake near Delcambre in Iberia Parish, Louisiana, which unfortunately is right above a huge salt deposit that had been mined for years by the Diamond Crystal Salt Company.  The problem is, the area is also a prime spot for oil drilling -- oil deposits and salt domes are frequently found in the same geological context -- and a Texaco oil rig drilling in the lake floor accidentally punched through into a cavern that had been excavated by the Salt Company.  Suddenly the bottom of the lake collapsed, creating a vortex like water going down a bathtub drain as the entire lake drained into the cavern.  The sinkhole swallowed the oil rig, eleven barges, a tugboat, hundreds of trees, and 26 hectares of land from the lake edge.  Where the lake had been, all that was left was an expanse of salty mud.

But back to the Sigsbee Escarpment.  The salient point here is that this same salt deposit, created during the Jurassic Period, extends offshore.  And that's where the second factor comes in.

The Laramide Orogeny is a complex series of events that is mostly responsible for raising the Rocky Mountains.  What had been relatively flat terrain, from Arizona up to Alberta, was now rapidly increasing in elevation and steepness.  Well, there's a general rule in geology that if you increase the angle at which a land surface sits, you increase the rate of erosion from running water; rivers run faster, can carry more suspended debris, and have a greater capacity for abrasion.  The raising of the Rocky Mountains meant that as they were lifted, the forces of erosion started tearing them down -- and all of that pulverized rock had to go somewhere.

Ultimately, any of it east of the Continental Divide ended up in the tributaries to the Mississippi River, and was flushed out into the Gulf of Mexico.

This plume of debris -- some of it from thousands of kilometers away -- settled out over the Jurassic salt deposits, and the weight of it started exerting significant downward pressure.  And salt -- especially the saturated salt mush that was at the bottom of the sea -- flows when it's compressed.  So like toothpaste squeezed from the world's largest tube, the salt domes squished outward, forming the lobes that are on the southern edge of the Sigsbee Escarpment.

Geologist Harry H. Roberts, of Louisiana State University, writes, "This process continues today.  As sediments have been continually added to the northern and northwestern Gulf rim, salt has been squeezed seaward in front of a constantly thickening wedge of sediment.  Today, the steep transition between the bottom of the continental slope and the deep Gulf floor, called the Sigsbee Escarpment, represents the old Jurassic Louann salt formation being squeezed seaward over much younger sediments."

So what started out seeming simple -- the steep boundary between continental shelf and deep ocean -- turns out not to be that simple after all, and way more interesting.

But that's how science is, isn't it?  Answering one question raises a hundred more, but that's the thrill of it.  As physicist Brian Greene put it, "Science is a way of life.  Science is a perspective.  Science is the process that takes us from confusion to understanding in a manner that's precise, predictive and reliable -- a transformation, for those lucky enough to experience it, that is empowering and emotional."

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The story of the bands

Something that strikes me about many scientific discoveries is how they so often come from someone noticing something the rest of us had overlooked or thought insignificant -- and afterward, most importantly, the person asking, "Why?"

A now-familiar example of this is the discovery by the father-and-son team of Luis and Walter Alvarez of the thin iridium-bearing clay layer at the boundary between Cretaceous rocks and Paleocene rocks -- analysis of which led to the discovery of the dinosaur-killing Chicxulub Meteorite Impact.  Without their questioning why there was a narrow layer of heavy-metal-enriched clay at the boundary, everywhere on Earth where there are rocks of that age, we might never have found out about one of the major events in the history of life on Earth.

Another example, less well known, has to do with the banded iron formations found in locations all over the world, including Australia, Brazil, Canada, India, Russia, South Africa, Ukraine, and the United States.  They're striking in appearance, sometimes hundreds of meters thick, with alternating layers of light-colored iron-poor and dark, reddish-brown iron-rich chert or limestone.  Here's an example from near Fortescue Falls in Western Australia:

[Image licensed under the Creative Commons Graeme Churchard from Bristol, UK, Banded iron formation Dales Gorge, CC BY 2.0]

Most of us, I think, would say "pretty rock formation" and leave it at that; a smaller number would recognize the fact that they were sedimentary, and wonder why the colors alternate.  Geologist Preston Cloud, though, took it several large steps farther -- and what he came up with is a little mind-blowing.

What first struck Cloud as curious about banded iron formations is that they're all about the same age.  Regardless of whether they're in Australia or Ontario, just about every banded iron formation studied was deposited around 2.4 billion years ago.  But what could create this pattern not just in one location, but in widely-scattered spots all over the planet?  Whatever the process was must have happened everywhere simultaneously -- and rapidly.

Cloud's hypothesis, which is now well-accepted, is that banded iron formations represent the fingerprint of something called the Great Oxidation Event.  Here's basically what we think happened.

Early living things were largely scavengers, living from abiotically-produced organic compounds dissolved in seawater (and the decomposing bits of dead cells).  These compounds were abundant -- an anoxic atmosphere, rich in reducing compounds like ammonia, methane, and carbon monoxide, together with an energy source like ultraviolet light, generates organic compounds of all sorts.  (As the Miller-Urey experiment conclusively demonstrated.)

But there's always competition between species, and sometimes mutations can create proteins or structures that allow organisms to able to access resources faster or more efficiently than their neighbors.  And that's what happened when a single-celled bacteria evolved a gene to produce chlorophyll, which can quickly capture energy from visible light and store it as chemical energy.

In other words: photosynthesis.

This had only one downside, but it was a huge one.  Photosynthesis generates molecular oxygen.  Oxygen is highly reactive, a strong oxidizer (thus the name), and tears apart organic compounds as quickly as they form.  The presence of oxygen, first dissolved in seawater and then liberated into the atmosphere, did three things.

First, it shut off the abiotic production of excess organic compounds, eliminating the food source for most of life on Earth.

Second, it was directly toxic to most cells, except for the (very) few which had detoxifying enzymes like superoxide dismutase to cope with living in an oxygenated environment -- or which were capable of metabolizing it, using a pathway we now call aerobic respiration and which we have become completely dependent upon.  (It's amazing to think about, but our energy-production system originally evolved as a way to mitigate the poisonous effects of molecular oxygen.)

Third, the oxygen reacted with dissolved ferrous (II) ions in seawater, and altered them to mostly-insoluble ferric (III) ions, which settled out on the ocean floor.  This process, however, bound up the available oxygen, so the reaction dropped oxygen levels, and for a while any iron eroded into the oceans was dissolved as ferrous ions again.  But eventually the photosynthesizing bacteria pumped out enough oxygen that the iron precipitated once more.  The result: alternating layers of iron-poor chert when the oxygen levels were low, and iron-rich chert when the oxygen levels rose.

Eventually, of course, the oxygen rose and stayed high.  By this time, damn near all life on Earth had died; the only ones left were anaerobes that could hide (like the bacteria we still have in deep-sea mud and other anaerobic habitats), and aerobes like our own ancestors that had metabolic pathways to cope with the presence of oxygen.

And the alternating pattern of light and dark layers in banded iron formations chronicle the rising and falling of oxygen during one of the pivotal moments of Earth's prehistory.

Certainly a large part of being a successful scientist is intensive training in a specific field, but I think sometimes there's not enough attention given to another facet of it -- the role of creativity.  The scientists who make important discoveries are usually the ones who notice things the rest of us might just walk past, wonder about them, and most importantly, draw connections between disparate realms to find answers (in this case, geology, chemistry, and biology).  Without this combination of technical knowledge, curiosity, and insight, we would know far less about the universe we live in -- and what an impoverished understanding we would be left with.

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Quantum pigeons

I have a fascination for quantum physics.  Not that I can say I understand it that well; but no less than Nobel laureate and generally brilliant guy Richard Feynman said (in his lecture "The Character of Physical Law"), "If you think you understand quantum mechanics, you don't understand quantum mechanics," so I figure I have a pretty good excuse for my lack of deep comprehension.  I have a decent, if superficial, grasp of such loopy ideas as quantum indeterminacy, superposition, entanglement, and so on, but that's about the best I can do.  At least I understand enough to find the following joke absolutely hilarious:

Heisenberg and Schrödinger were out for a drive one day, and they got pulled over by a cop.  The cop says to Heisenberg, who was driving, "Hey, buddy, do you know how fast you were going?"

 
Heisenberg says, "No, but I know exactly where I am."

 
The cop says, "You were doing 85 miles per hour!"

 
Heisenberg throws his hands in the air and responds, "Great!  Now I'm lost."

 
The cop scowls at him.  "All right, pal, if you're going to be a smartass, I'm going to search your car."  So he opens the trunk, and there's a dead cat inside it.  He says, "Did you know there's a dead cat in your trunk?"

 
Schrödinger says, "Well, there is now."

Thanks, you're a great audience. I'll be here all week.

In any case, the topic comes up because of a paper in Proceedings of the National Academy of Sciences called, "Experimental Demonstration of the Quantum Pigeonhole Paradox," by a team of physicists at China's University of Science and Technology, which was enough to make my brain explode.  Here's the gist of it, although be forewarned that if you ask me for further explanation, you're very likely to be out of luck.

There's something called the pigeonhole principle in number theory, that seems kind of self-evident to me but apparently is highly profound to number theorists and other people who delve into things like sets, one-to-one correspondences, and mapping. It goes like this: if you try to put three pigeons into two pigeonholes, one of the pigeonholes must be shared by two pigeons.

See, I told you it was self-evident.  Maybe you have to be a number theorist before you find these kind of things remarkable.

[Image licensed under the Creative Commons Razvan Socol, Rock Pigeon (Columba livia) in Iași, CC BY-SA 3.0]

In any case, what the research showed is that on the quantum level, the pigeonhole principle doesn't hold true.  In the experiment, photons take the place of pigeons, and polarization states (either horizontal or vertical) take the place of the pigeonholes.  And when you do this, you find...

... that when you compare the polarization states of the three photons, no two of them are alike.

Hey, don't yell at me.  I didn't discover this stuff, I'm just telling you about it.

"The quantum pigeonhole effect challenges our basic understanding….   So a clear experimental verification is highly needed," study co-authors Chao-Yang Lu and Jian-Wei Pan wrote in an e-mail.  "The quantum pigeonhole may have potential applications to find more complex and fundamental quantum effects."

It's not that I distrust them or am questioning their results (I'm hardly qualified to do so), but I feel like what they're claiming makes about as much sense as saying that 2 + 2 = 5 for large values of 2.  Every time I'm within hailing distance of getting it, my brain goes, "Nope.  If the first two photons are, respectively, horizontally polarized and vertically polarized, the third has to be either horizontal or vertical."

But apparently that's not true. Emily Conover, writing for Science News,writes:

The mind-bending behavior is the result of a combination of already strange quantum effects.  The photons begin the experiment in an odd kind of limbo called a superposition, meaning they are polarized both horizontally and vertically at the same time.  When two photons’ polarizations are compared, the measurement induces ethereal links between the particles, known as quantum entanglement.  These counterintuitive properties allow the particles to do unthinkable things.

Which helps.  I guess.  Me, I'm still kind of baffled, which is okay.  I love it that science is capable of showing us wonders, things that stretch our minds, cause us to question our understanding of the universe.  How boring it would be if every new scientific discovery led us to say, "Meh.  Confirms what I already thought."

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The problem with intercessory prayer

There are many things I don't get about religion, but one of the ones I understand least is the idea of intercessory or petitionary prayer -- prayer that has as its intent to alter the course of something unpleasant like an illness or run of bad luck.

The Bible is full of examples of intercessory prayer, of God's wrath being turned away by a devout word in the Divine Ear.  In the episode of the Golden Calf (Exodus chapter 32), God apparently intended to destroy the Israelites for idolatry, but his judgment was altered by Moses' plea.  Even Sodom and Gomorrah, those pinnacles of depravity from the book of Genesis, would have been saved had Abraham found ten or more "righteous men" there.

All of this, to my admittedly unqualified ear, sounds as if God could change his mind.  The problem, so far as I can frame it, is this; in the typical Christian model of how things work, God is changeless, eternal, all-good, and all-knowing.  As such, the whole idea of a person's prayer altering the course of what God wants is a little silly.  God presumably already knows not only what is the best outcome, but knows what will happen; why would the prayers of one person, or even of everyone on Earth simultaneously, change that?  And what happens when you have equal numbers of devout people praying for opposite outcomes -- like what happens in the United States at every high-stakes sports event?  Does God simply tally up the number of prayers, or does the intensity of the prayers count?  Or the piety of those who are praying?

Old Woman in Prayer by Gerrit Dou (ca. 1630) [Image is in the Public Domain] 

So, in my effort to understand this idea, I turned to C. S. Lewis.  Even if I usually disagree with Lewis' conclusions, I find him to be generally rational, and certainly a clear, sober-minded writer on the subject.  Here's what I found, from his essay "Does Prayer Work?":

Can we believe that God ever really modifies His action in response to the suggestions of men?  For infinite wisdom does not need telling what is best, and infinite goodness needs no urging to do it.  But neither does God need any of those things that are done by finite agents, whether living or inanimate.  He could, if He chose, repair our bodies miraculously without food; or give us food without the aid of farmers, bakers, and butchers, or knowledge without the aid of learned men; or convert the heathen without missionaries.  Instead, He allows soils and weather and animals and the muscles, minds, and wills of men to cooperate in the execution of His will.

So far, sounds like the God/No God models look kind of the same.  But Lewis goes on to say:

I have seen it suggested that a team of people—the more the better—should agree to pray as hard as they knew how, over a period of six weeks, for all the patients in Hospital A and none of those in Hospital B.  Then you would tot up the results and see if A had more cures and fewer deaths.  And I suppose you would repeat the experiment at various times and places so as to eliminate the influence of irrelevant factors.

The trouble is that I do not see how any real prayer could go on under such conditions.  “Words without thoughts never to heaven go,” says the King in Hamlet.  Simply to say prayers is not to pray; otherwise a team of properly trained parrots would serve as well as men for our experiment.  You cannot pray for the recovery of the sick unless the end you have in view is their recovery.  But you can have no motive for desiring the recovery of all the patients in one hospital and none of those in another.  You are not doing it in order that suffering should be relieved; you are doing it to find out what happens.  The real purpose and the nominal purpose of your prayers are at variance.  In other words, whatever your tongue and teeth and knees may do, you are not praying.  The experiment demands an impossibility. 

What brings this up today is that a team in Brazil did exactly what Lewis suggests -- not with "properly trained parrots," but with a group of the devout who were told to pray for a group of COVID-19 sufferers, and who were honestly desirous of a positive effect.  The people doing the praying weren't told not to pray for the other group; in the setup of the experiment, they didn't even know the other group existed, so this circumvents Lewis's objection that the prayers wouldn't be valid because the people praying would only be "doing it to find out what happens."

The results, which appeared this week in the journal Heliyon, found zero difference in the survival rate, severity, or rate of complications between the prayed-for and not-prayed-for groups.

I am very curious as to how a Christian would explain why, if intercessory prayer works at all, the prayed-for group didn't show a lower risk of complications or death.  "Thou shalt not put the Lord thy God to the test," perhaps -- but all that means is that the scientists running the experiment were sinning, and you'd think God wouldn't be petty enough to let the prayed-for group suffer and die just to get back at the researchers.

Plus, there's the consideration that if ever there was an opportunity for God to show that what the Christians claim is correct, this is it.  You would think that if presumably God wants people to believe and to pray (and in fact Christians are positively commanded to pray, in a variety of places in the Bible), some sort of results would have been forthcoming.

You get the impression that even Lewis was a little uncomfortable on this point.  He said, "Prayer doesn't change God -- it changes me."  Again, I have to wonder how this would work.  How would praying for something to a deity whose mind I can't change, who knows what is "supposed to happen" and who will do what he chooses regardless, have any beneficial effects on me?  Imagine a parent whose mind could never be swayed by his children's requests -- and telling the children, "You should ask anyway, because it's good for you."

While I am not religious (obviously), I can at least understand the concept of other sorts of prayer -- prayers for enlightenment, prayers for understanding, prayers for courage.  But I really have no clue what the possible logic could be to praying for intercession, other than "the Bible says we have to -- never mind why."  Perhaps some reader will have a good explanation of it, but on the face of it, it seems like the most pointless of pursuits.

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Message in a bottle

Ever heard of a witch bottle?

Witch bottles are magical items that are a type of apotropaic magic -- spells meant to ward off evil (the word comes from the Greek αποτρέπειν, meaning "to turn away from").  The idea has been around for a long time; if someone tries to use an evil enchantment on you, you can respond with a defensive spell of your own, and it might even rebound on the person who was trying to hex you.  One of the first written accounts of a witch bottle is in seventeenth century English clergyman Joseph Glanvill's book Saducismus Triumphatus, or Evidence Concerning Witches and Apparitions, wherein we hear about a man whose wife was sick and who kept getting visited by the apparition of a bird that would flutter in her face, because apparently that was a thing in seventeenth-century England.  The man was given advice by an "old man who traveled up and down the country," who said the cure was to have the sick woman pee in a bottle, then add some pins and needles, then cork it up tight and put it in the fire.

Which, I have to admit, is at least a creative solution.

The first time it didn't work because the heat made the air in the bottle expand and blew out the cork, which must resulted in a situation that was unpleasant to clean up.  But they tried a second time, and it worked -- and had an interesting result:

Not long after, the Old Man came to the house again, and inquired of the Man of the house how his Wife did.  Who answered, as ill as ever, if not worse, and still plagu'd by birds.  He askt him if he had followed his direction.  Yes, says he, and told him the event as is above said.  Ha, quoth he, it seems it [the spirit which was troubling them] was too nimble for you.  But now I will put you in a way that will make the business sure.  Take your Wive’s Urine as before, and Cork, it in a Bottle with Nails, Pins and Needles, and bury it in the Earth; and that will do the feat.  The Man did accordingly.  And his Wife began to mend sensibly and in a competent time was finely well recovered; But there came a Woman from a Town some miles off to their house, with a lamentable Out-cry, that they had killed her Husband.  They askt her what she meant and thought her distracted, telling her they knew neither her nor her Husband.  Yes, saith she, you have killed my Husband, he told me so on his Death-bed.  But at last they understood by her, that her Husband was a Wizard, and had bewitched this Mans Wife and that this Counter-practice prescribed by the Old Man, which saved the Mans Wife from languishment, was the death of that Wizard that had bewitched her.

Apparently other things that people sometimes put in witch bottles were hair, blood, fingernail clippings, red thread, written charms, feathers, dried herbs and flowers, and money.

The reason this comes up is that apparently there are still people who believe in this, because there's a beach in southern Texas where a guy keeps finding what appear to be modern witch bottles.  He's found eight of them thus far, all filled with odd items -- sticks and leaves seem to be the most common.

[Image licensed under the Creative Commons Malcolm Lidbury (aka Pinkpasty) , Witch Bottles Curse Protection, CC BY-SA 3.0]

Jace Tunnell, Director of Community Engagement at the Harte Research Institute, has spent years scouring the beaches of South Padre Island for anything odd that's washed up, and starting about six years ago, he began finding sealed bottles that evidently had been out there adrift for a long time, given the fact that some of them had barnacles on them.  After studying the currents, he believes they may have come from as far away as the islands of the Caribbean, or perhaps even West Africa.

"I don't open the bottles," Tunnell said.  "In fact, my wife won't even let me bring them into the house.  The theory is that if you open it you can let the spell out, whatever the reason the person had put the spell in there.  They're counter-magical devices, created to draw in and trap harmful intentions directed at their owners, so it's best to leave them sealed."

The fact that some of them could contain piss and rusty needles is another good reason to leave the tops on.

Predictably, I don't think there's any other particularly good reason to be concerned about them.  You have to wonder, though, how these superstitions get started, and (especially) how they persist despite the fact that they don't work (notwithstanding accounts like the one from the estimable Mr. Glanvill).  I wonder if it's because sometimes the "cursed" person does get better after the counter-curse, and to the credulous this is sufficient proof, even though it is an established scientific principle that the plural of "anecdote" isn't "data."

Although you have to wonder about the sanity of the first person who came up with the idea of peeing in a bottle full of pins.

In any case, if you find a sealed bottle washed up on the beach, it's probably best just to deposit it in the nearest trash can and not worry about it.  Unless it contains money, in which case open that sucker right up.  Call me greedy, but I'd risk being plagu'd by birds if the price was right.

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Analysis of a cataclysm

Any idea what volcano is responsible for the largest known eruption?

Krakatau?  No.  Vesuvius and the Campi Flegrei?  Not even close.  Tambora or Toba?  Nope.  The Yellowstone Supervolcano?  Closer, but still not right.

The biggest volcanic eruption on record came from an extinct caldera I'd never heard of until a friend and loyal reader of Skeptophilia mentioned it a couple of days ago.  It's the La Garita Caldera in southwestern Colorado, near the little town of Creede, and when it last erupted -- during the Oligocene Epoch, on the order of 28 million years ago -- it did so with an estimated force of 250,000 megatons, which is five thousand times the explosive force of the largest nuclear weapon ever detonated.

The eruption resulted in something called ignimbrite -- a rock layer created from a frozen pyroclastic flow.  When a volcano powered by viscous high-silica (felsic) magma erupts, it's usually explosive, quite unlike the runny, flowing lava from one made of low-silica (mafic) rock.  Instead of creating a liquid flow, the force of the eruption pulverizes the magma and surrounding rock, creating a superheated cloud of ash, dust, and volcanic gas that then rushes downhill, incinerating anything in its path.  This is what did in Pompeii and Herculaneum in 79 C. E., and more recently, occurred during the devastating eruption of Mont Pelée on Martinique in 1902 that killed thirty thousand people in the space of a few minutes.

An ignimbrite forms when the pyroclastic flow loses speed and settles, and the ash, pumice, and glass shards (still plenty hot) fuse together to form a solid layer of rock.  If you've seen pictures of Pompeii (or better yet, been there) you can picture what this looks like, and your mental image is probably of something like a meter's worth of consolidated ash.

The La Garita Caldera eruption produced an ignimbrite an average of a hundred meters thick.

The amount of rock and magma blown to smithereens in the eruption is estimated at around five thousand cubic kilometers -- compare that to the one cubic kilometer blown skyward when Mount Saint Helens erupted in 1980, and you have an idea of the scale.  The resulting rock formation, the Fish Canyon Tuff, covers 28,000 square kilometers.

[Image is in the Public Domain courtesy of photographer G. Thomas]

The most interesting part of this is what caused the eruption.  It's part of the larger San Juan Volcanic Field that was created when the center of the North American continent was stretched and cracked by the Rio Grande Rift.  This is a long, north-south trending fault running from northern Mexico up through New Mexico and into central Colorado, and was responsible for a number of eruptions between forty and eighteen million years ago (although none as big as La Garita).  The reason for this fault, in the middle of the stable continental craton, is still being puzzled over by geologists, but here's one possible explanation.

Starting during the Cretaceous Period, a huge slab of oceanic crust called the Farallon Plate subducted underneath the North American Plate.  This had a couple of major effects -- cementing a number of island arcs onto the west coast of North America (called suspect terranes because they don't have the same geology as the neighboring land they're welded to), and triggering the Laramide Orogeny that created at least parts of the Rocky Mountain Range.

[Nota bene: the geology of the Rocky Mountains is ridiculously complicated, so what I'm presenting here is a vast oversimplification.  If you want a great overview of it, as well as the geology of other parts of North America and the people who study it, a good place to start is the excellent quartet of books by John McPhee, Rising From the Plains, Basin and Range, In Suspect Terrain, and Assembling California.]

In any case, the Farallon Plate was eventually consumed by the subduction zone, leaving only three small pieces still in existence -- the Gorda, Juan de Fuca, and Explorer Plates, which I considered in my post about the Cascadia Fault a month ago.  The rest of Farallon is now underneath western North America.

And, more germane to our topic, the rift zone that powered it eventually got dragged underneath as well.  This meant that the force pushing the Farallon and Pacific Plates apart was now beneath the North American continent.  The result was that the continental crust was stretched, creating a topography called horst-and-graben (or basin-and-range), where extension cracks the rock layers and some of them sink downward, creating an alternating step-up and step-down landscape that you see all over Colorado, Utah, and Nevada.

But along the Rio Grande Rift, the cracks ran so deep that it didn't just cause earthquakes and topographic change.  The fault went down far enough that magma upwelled into the fissure, resulting in a chain of volcanoes -- the aforementioned San Juan Volcanic Field, one of which is the cataclysmic La Garita Caldera.

Eventually -- and fortunately -- the convection current powering the spreading center ran out of steam due to friction with the thick, cold continental crust, and the whole thing simmered down.  The last ignimbrite from the San Juan Volcanic Field is about eighteen million years ago, and the entire area has been geologically quiet since that time.

Whenever I find out about something like this, I'm awed by the power of which the Earth is capable.  We tend to flatter ourselves about our own capacity for controlling nature, but by comparison, we're pretty damn feeble.  Being reminded of this is not, of course, a bad thing -- especially since at the moment our activities stand a good chance of unleashing a backlash from the climate that could be nothing short of catastrophic.

It's best to keep in mind that in a war between nature and humanity, the odds are very much in favor of nature.

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