the legend of finn mccool

Irish legend is rife with memorable characters, among them a giant named Fionn mac Cumhaill -- or, more colloquially, Finn McCool. As with all myths, the details vary but the essence of the tale is this. Finn McCool lived on the north coast of Ireland with his wife Oonagh. One day his rival, the Scottish giant Benandonner began taunting him from across the channel  -- the usual "I'm bigger and tougher than you, little wuss-boy" macho drivel, no doubt accompanied by much beating of chests and flexing of biceps. (Clearly Benandonner was a wee bit insecure, perhaps because he didn't have a catchy moniker like Finn McCool.) Put bluntly, Benandonner said he could kick Finn's ass if only that pesky channel wasn't in the way to stop him. No self-respecting giant would stand for that insult to his masculinity. So Finn called his rival's bluff, and built a causeway (bridge) out of huge stones across the water, since no boat at the time was large enough to hold a giant. And he invited Benandonner to come right on over and prove his point.

The variations diverge at this point, with some versions saying Finn merely wanted a chance to rest before the confrontation, after exerting so much energy to build the causeway, and others claiming he was frightened when Benandonner loomed into view and he realized his rival was indeed the bigger, stronger giant. (I'm inclined to favor the latter.) Finn's wife Oonagh was smarter than either male giant; she knew that battles aren't always won on the basis of size and strength. She suggested stealth. She disguised her husband as a baby in a large nightgown and bonnet -- possibly even a supersized rattle -- and placed him in a gigantic cradle. When Benandonner arrived, she invited him in for tea and asked him to be quiet so as not to wake the "baby." Benandonner took one look and decided that if this enormous creature was Finn McCool's infant, he had no desire to meet the father, and fled home to Scotland, ripping up the causeway behind him to ensure Finn McCool couldn't follow him. (Jen-Luc Piquant thinks this proves they were both pathetic girly-men, for all their tough talk and macho posturing.)

The remnant of Finn McCool's legendary bridge is still there, in what is now County Antrim in Northern Ireland. It's called the Giant's Causeway, and is considered one of the seven wonders of the United Kingdom. Justly so -- it consists of nearly 40,000 interlocking basalt columns, some as tall as 36 feet. The tops of the columns form "stepping stones" leading form the foot of the cliffs before disappearing under the sea.  I've had the privilege of standing on those columnar formations in person, during a visit to Northern Ireland many years ago, and they're pretty damned impressive. (The locals at the time were far from welcoming. We stopped off for a quick bite at a local pub in Bushmills, and all conversation ceased the moment we walked in. The bartender slipped into the back, never to be seen again, and after waiting 20 minutes in total silence -- a highly unnatural state for a pub -- we got the message and took our leave. To this day, I still don't know what was going on. But the causeway? It's bloody breathtaking.)

Finn McCool is just a legend, on a par with the American giant, Paul Bunyan, dreamed up to explain how such a bizarre formation like the causeway ever came into being in the first place. It looks far too regular in terms of its patterned structure to have been caused by natural processes. And yet it did. First "discovered" in 1692 by the then-Bishop of Derry, Sir Richard Bulkeley II officially announced the causeway's existence in a presentation before the Royal Society of London, of which he was a member.

(Historical sidenote: There's little record of Sir Richard II -- a Google search yielded plenty of information about his father, but little about the son, who left no heirs and was therefore the last scion of that particular baronetcy. He was apparently deformed, but well-educated, a fellow of Trinity College and at Oxford, and in addition to his paper on the Giant's Causeway, he also presented papers on a self-propelling chariot of his own invention, and a scheme for improving Ireland by cultivating the planting of maize. Alas, he succumbed to religious fervor in his dotage, falling in with a cult of self-proclaimed French prophets whom he believed would cure him of his deformity. They didn't.)

Theories abounded as to how the causeway had formed: some said men had made it with picks and chisels, and of course, there was the legend of Finn McCool. The scientists were inclined to favor nature but were mystified as to the mechanism until 1771 when a Frenchman identified only as Demarest announced that it was the result of volcanic activity. (There's even less Google-info on Demarest than there is on poor Sir Richard II.) That's still the accepted explanation, although it's continually being refined as science progresses. The columnar joints that make up the causeway were formed roughly 60 million years ago by the cooling and shrinking of molten lava from a massive volcanic eruption.

According to physicist Lucas Goehring of the University of Toronto, who presented a paper today at the APS March Meeting on his recent work in this area with fellow Toronto colleague Stephen Morris, this is what probably happened. When the lava flowed into the sea, it quickly cooled, contracted, and crystallized into the near-perfect hexagonal columns we see today. (In fact, geologists believe there were three major lava flows, giving rise to lower, middle and upper basaltic layers, with the causeway columns occurring in the middle layer.) That kind of shrinkage inevitably causes stresses that fracture the rock. Per Goehring: "The columns are formed as a sharp front of cooling moves into the lava flow, assisted by the boiling of groundwater. As the front advances, it leaves behind a crack network which evolves into an almost hexagonal arrangement. This network carves out the columns."

Columnar joints are more common than one might think: they are also found at Devil's Tower National Monument in Wyoming, at the "Organ Pipes" formation on Mount Cargill in New Zealand, and at the Devil's Postpile National Monument in California. Similar structures can be created with a simple kitchen experiment: mix equal parts corn starch and water and place into a coffee cup. Dry the mixture by shining a bright light above it. Within a week or so, the mixture will be completely dry and you can break it apart to reveal an interior that is broken up into "starch columns."

In addition to studying the genuine article in situ in both Ireland and Scotland, Goehring and his cohorts have figured out how to control this tabletop kitchen experiment so precisely that they can study the formation process in much greater detail than scientists could in the past, augmented by X-ray tomography to give the first genuinely 3D imaging of the internal structure of the columns. Among the more surprising findings: (1) the columns are not quite as perfectly hexagonal as previously believed, and (2) the continuous dynamics of the formations can be found even deep inside the structure, similar to, say, dry foams. Also, the size of the columns depends on the speed at which the cracks advance, and the rate at which the water can move through the starch. That's why lava-formed columns are 1000 times larger than the tabletop experiment: the analogous properties of lava are much slower.

I'm always appreciative of how much of scientific knowledge seems to get its start simply because someone took the time to notice unusual patterns or structures in nature, and set about asking questions, forming hypothesis, and devising ways to test those ideas. For instance, sharing the session with Goehring was  Meredith Betterton of the University of Colorado, Boulder, who became enthralled by the large icy spikes -- called penitentes because they resemble a procession of white-hooded monks -- she observed while viewing glaciers in the Andes.  "I thought, 'Wow, what's going on here?'" she admits, and being a scientist, she set about figuring it out. (She's not the first to be thus fascinated. Charles Darwin described penitentes in 1839, while relating a March 1835 excursion in which he squeezed his way through snowfields covered in penitentes on the way from Santiago, Chile, to the Argentine city of Mendoza.)

Along with colleagues at the Ecole Normale Superieure in France, Betterton created the first artificial versions of these spiky ice formations, which can be found quite frequently on high-altitude glaciers where the air is particularly dry. She also devised a mathematical model to predict the process. The hope is that this research will yield useful insights into how glaciers evaporate; it may also lead to a practical strategy for preserving glaciers in light of global warming.

There's probably a fascinating legend somewhere on a par with Finn McCool to explain how these spikes of ice form, but science is more than capable of stepping with its own explanation. Penitentes arise when the sun's rays evaporate snow in such a way that the ice turns directly into water vapor, without melting into water first. The process is called sublimation. The snowy surface might start out smooth, but it gradually develops depressions as some areas sublimate faster than others, and the resulting curved surfaces concentrate more sunlight and speed up the sublimation even more, leaving behind a forest of towering spikes of ice. Penitentes are nature's ice sculptures.

Rising temperatures slow the formation of penitentes quite a bit, an especially alarming factor in light of global warming, because fewer ice spikes could accelerate the melting of glaciers. The spikes cast shadows, you see, and serve as a natural cooling mechanism. There's a working hypothesis that spreading a small layer of dirt over glaciers could help preserve them by fostering faster formation of penitentes. This turned out to be true with the small-scale versions Betterton created in her lab. She spread printer toner on her artificial snow layer to simulate pollutants common to glaciers around the world, and found that the ice spikes grew more rapidly as a result. It's a bit counter-intuitive, since carbon-based pollutants actually increase melting rates on glaciers because the ice absorbs more sunlight and therefore heats up more quickly. The formation of more penitentes could offset that damage.

Not that Betterton thinks she has all the answers now about the mechanisms behind penitentes -- not by a long shot. "There's lots of things not yet explained, and that's what makes this field so fascinating," she said.

(Postscript: In my last post I mentioned that the folks at Physics Buzz are also blogging the March Meeting. This is true, but they're doing it at a separate site, so for their ongoing coverage, check it out here.)

Comments

[Blake Stacey]

A man known only as Demarest? Holy Jebus, I think he's my cousin.

No joke. There are Demarests on my mother's side if you go back a few centuries. I think they originally sprang from an aristocratic house called De Maret, or something like that.

Carry on, carry on. . . .

[Quasar9]

"fellow of Trinity College and at Oxford, and in addition to his paper on the Giant's Causeway, he also presented papers on a self-propelling chariot of his own invention, and a scheme for improving Ireland by cultivating the planting of maize"

lol, talking about myths
You should see the advert for Jolly Green giant sweetcorn - yep advertising (myth) to get kids to eat their greens - or in this case yellow sweetcorn

"Penitentes arise when the sun's rays evaporate snow in such a way that the ice turns directly into water vapor, without melting into water first. The process is called sublimation. The snowy surface might start out smooth, but it gradually develops depressions as some areas sublimate faster than others, and the resulting curved surfaces concentrate more sunlight and speed up the sublimation even more, leaving behind a forest of towering spikes of ice. Penitentes are nature's ice sculptures."

Penitentes, are those guys who dress up like KKK - at Easter in Spain. Masonic brotherhoods, walking barefoot (or whatever) in procession for hours in the night, their long candles with molten max slowly dripping down the side are said to ressemble these towering spikes, or should I say viceversa.

[Mark]

On your visit to N Ireland, did you happen to get down to the Republic of Ireland? A few years ago we visited and ate in a few very local pubs, where we found people uniformly pleasant and friendly, if somewhat difficult for us to understand. One particularly friendly, slightly tipsy fellow was happy to learn that my mother's maiden name was Kennedy.

[Jennifer Ouellette]

Mark, I only got down to the northernmost tip of the Republic of ireland, but yes, the folks were friendlier. So were the folks in belfast proper -- it was only farther north that the populace viewed outsiders with extreme suspicion... In Belfast, one day I gave a pound to a couple of guys in the park who were panhandling. They openly admitted they intended to use it to buy whiskey and I admired their honesty. They came back 15 minutes later with three bottles of the cheapest alcoholic beverage imaginable -- also the most potent. It was like drinking battery acid. Still, it's the thought that counts. Even the panhandlers will share their drinks with you. :)

[Kea]

Nice to see a blurb on glaciers. Yes, the Andes is the only place I have seen the penitentes. They can be quite an obstacle!

[dzimm]

I believe that it was Isaac Asimov that said

'The most exciting phrase to hear in science, the one that heralds new discoveries, is not Eureka! (I found it!) but rather, "hmm.... that's funny...."'

[Lee Kottner]

Your cool welcome could have been due to the jerk you were traveling with, although I met the same sort of welcome in North Wales, in the company of someone who'd grown up there. Of course, she'd had the audiacity to leave town and go to college, AND go abroad to America! Not to mention bringing one of them back to visit.

Great post, Jen. This formation has always fascinated me. I always sort of envisioned it as an extrusion, like toothpaste, or those Play-Doh factories.

[Markk]

Basalt columns are also found at Tower falls in Yellowstone (you are looking at them from the side when you look across the valley to the North. Also in my favorite spot in the Hebrides the island of Staffa (Right by Iona) where in Fingal's cave on a nice day you can look at the bottom of the columns, and walking to the cave the "giants" footsteps are just as awesome as in Ireland. That cave also has such a great resonance that Mendelsohn was supposedly inspired to write the Hebrides symphony from being there, and in the 1800's I heard they would bring in strings to play (on nice days). Awesome volcanic forms all over that area of the world.

[d chedwick]

i love the Giant's Causeway I have a zillion cousins in Donegal, so it is a quick drive to the Causeway when I visit them) I hike all around and enjoy the beauty of the place. It is an amazing amazing place!

[d chedwick]

Oh I can explain your Bushmills pub experience / it is a very very common occurance.

[Stephen Morris]

Wonderful stuff!

Its a great problem, with a great history. I didn't know all that stuff about Sir Richard. Ironically, I have since learned that the history is more compicated. The Giant's Causeway was announced to the Royal Society in 1689 by Sir Robert Redding, although the first published paper was by Bulkeley.

Redding sent a letter to the Roy Soc, which was read out at one of their meetings, January 1689, and minuted accordingly. The original letter no longer exists, but the minutes read:

" There was read Sr. Robert Reddings Description of ye Giants Causey within
2 miles of Dunluce, to the north thereof, in the County of Antrim in
Ireland: where there are a vast quantity of Hexagonall Pillars of stone
about 8 Inches side, which stand pitch’t perpendicularly as in a Pavement
runing down obliquely into the Sea. These Columns are so regularly ranged
and fitted one to the other that it seems rather the work of art than
nature, and they are made up of pieces of about 8 Inches deep, the Convexity
of the bottom parts entering into a Cavity in the Top of [the] next under it
made to receive it."

Actually if you read Bulkeley's paper closely he hints at this letter which
he'd obviously heard of, or perhaps even read, and the minuted account of
Bulkeley's paper reading to the RS also cross references Redding briefly,
though not by name or date. Minutes freely available in the Royal Society.

I learned all this from an Irish geography student, Alasdair Kennedy, who is writing a thesis on this stuff.

Another oddity: You say "When the lava flowed into the sea, it quickly cooled...". This was in the APS press release, but they just made that up. There was no sea there to flow into 60 million years ago, as that part of the atlantic had not opened yet. So there you are. It was just a wet jungle environment. You can even see a red layer that marks the (burned, compressed) jungle between the basalt flows.

Keep it up!

[Nolan Porterfield]

My wife and I visited Northern Ireland in 1983 and got the same cold shoulder. But of course that was at the height of the Troubles. Today it's quite different. We were in Belfast and the northern counties twice this year and were warmly received, possibly because I was quick to mention that my great-grandfather emigrated from County Tyrone to the U.S. in 1852. The Giant's Causeway is indeed a sight to behold. If you go there, by all means pick up a copy of the illustrated "re-telling" of the Finn McCool story, by "Daniel Ferguson" (Stephen Hall). It's a hoot.

[Aislinn]

Really good article, but I have to argue with -one- point you made. Finn mcCool wasn't a giant. He was human-sized, if slightly taller than the average for those days. If you read the other legends/myths about him, you'll see they never claim him to be a giant. Son of a God, oh yes, giant? No.

[Sara]

Here's some more - on their side, so to speak - Karitane Beach, South Island, New Zealand - http://trunc.it/4se1o