A Wonderful Life

Sir isaac Newton December 25-1642 - March 31, 1727

          Sir Isaac Newton, born December 25, 1642

Are you ready? Just 7 more shopping days until December 25th – Newton’s birthday.* People celebrate Sir Isaac Newton’s birthdate in interesting ways. In this part of the world, there are a lot of coloured lights, decorated trees, and shiny tinsel. Stores all over our city are running specials (although the best sales are on Newtonian Boxing Day, December 26). All in all, it’s a festive occasion and a great way to remember the man who brought us gravity, optics, calculus, and all those laws of motion. Newton would be 372 years old next week, had he not been stricken by the infirmities of elderliness. But I wonder what the world would be like if he had never been born? Would gravity work the same as it does today? Probably, but we should still celebrate the great man of physics.

George

George

There are a lot of fun ways to commemorate Newton’s birthday – each year one of our local TV stations broadcasts the great science fiction classic, It’s a Wonderful Life, in honour of Newton. The movie probes the idea of how vastly different the world might be if one person – let’s call him George – had never been born. In the absence of George, the Earth suffers a devastating dystopia as gambling, jazzy music, and boozing abound. Without George, the world is a far different place. It’s just a movie, of course, so we will never know the impact of just one George. However, Harvard paleontologist Stephen Jay Gould pursued the idea by investigating the evolution of life on Earth as it might have been, had the peculiar creatures of the Burgess Shale survived and had the Cambrian extinction not taken place.

Stephen Jay Gould, cover of Newsweek, 1982

Stephen Jay Gould, cover of Newsweek, 1982

Gould’s thought experiment – what our planet would be like without that one single extinction event –  is part of his outstanding 1989 book, Wonderful Life. Catchy title, isn’t it? I have a signed copy of the book. Not signed by Professor Gould, but signed instead by my former co-workers who presented the book to me when I resigned from a big, big, big corporation (I think it is the world’s largest.) where I had briefly worked. The signatures of my co-workers mean more to me than Gould’s name inscribed in the book would have meant, though I liked Stephen Jay Gould and immensely enjoyed a talk he gave here in Calgary in 1991, the year Wonderful Life was a finalist for the Pulitzer Prize. Gould spoke about his book and the evolution of life. He was great.

Here is my three-paragraph recap of Gould’s Wonderful Life: The Burgess Shale and the Nature of History. Yes, the book has a subtitle. This narrows the scope of the book down to Canada’s Burgess Shale and the entire Nature of History. Gould is up to the task. Gould believed that chance was one of the crucial factors in the evolution of life on Earth and survival of the fittest might actually be survival of the luckiest. Controversially, Gould suggests that fitness for existing conditions does not guarantee long-term survival. If environmental conditions change abruptly, species survival may depend mostly on luck. It could also mean that the best adapted creatures for the present environment will be replaced by marginal creatures that have attributes unexpectedly suited to a suddenly changed environment. This certainly challenges “survival of the fittest” – those best adapted for the present environment might not win the longevity contest against some obscure maladapted creatures that were inadvertently prepared for some radically and abruptly changed future environment.

Hallucigenia - not your grandfather's ancestor.

Hallucigenia – not your grandfather’s ancestor.

Pikaia, arguably your grandfather's ancestor

Pikaia – arguably, your grandfather’s ancestor

A large part of Gould’s argument is based on remarkably well-preserved fossils in British Columbia’s Burgess Shale. The type of animals that thrived just after the Cambrian explosion (around 505 million years ago) would not normally have left fossils, but the muddy conditions (now a shale formation in the Rockies) captured their soft bodies’ outlines in surprisingly clear relief. Gould argued that during the Cambrian the Burgess fauna were perfectly adapted to their environment, but most of them left no descendants because conditions changed. Most Burgessites became extinct.

Importantly for Gould’s thesis, surviving creatures did not seem better adapted than the ones that went extinct. Stephen Jay Gould invites us to consider what the world would be like if we could roll back time, change the happenstance of the extinction event, and imagine that the world is now populated by descendants of Hallucigenia rather than Pikaia. Would the distant offspring of Hallucigenia have evolved into bloggers who could ponder this question?

But here we are.  And now, with the big Newton holiday quickly approaching, you might consider lighting a candle to one of science’s most brilliant brains. Or perhaps buying a copy of Wonderful Life for the science geeks in your circle of friends. It is sure to be appreciated.  Maybe it can become an annual tradition.

*About Newton’s birthday on December 25th 1642 . . . Most references cite January 4, 1643, the date it falls upon with our Gregorian calendar. But it was a Julian calendar hanging on his mum’s cottage wall when he was born, and it said December 25, 1642. This gives you a chance to celebrate his birth twice each year.

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Dinos 101: Everything You Ever Wanted to Know

Greeter at Tyrrell Museum (photo - Miksha)

Greeter at Tyrrell Museum (photo – Miksha)

Want to know about dinosaurs? You’re in luck. The University of Alberta is offering a free 12-week course, a MOOC (Massive Online Open Course) starting January 3rd. I am thinking of signing up for it – the course is offered through Coursera, a giant MOOC-clearinghouse. I’ve taken advantage of Coursera before – I took their Philosophy of Science (University of Edinburgh),  A Brief History of Humankind (Hebrew University of Jerusalem), Origins – Formation of the Universe, Solar System, Life and Earth (University of Copenhagen). I haven’t studied any MOOCs that were taught via a Canadian school, so I am looking forward to Phil Currie’s lectures from the University of Alberta. Dr Currie ran the Royal Tyrrell Museum of Palaeontology here in southern Alberta and he is a smart and capable presenter.

If you have never taken a MOOC, maybe this is the time to give it a try. The Coursera program is free (although you can purchase “Verified Certificates of Completion” if you want – I haven’t done this myself).  Give Coursera’s MOOC a try. You can always drop out if the material or time commitment (about 3 – 5 hours/week) doesn’t work for you. The January 3rd course is called Dino 101: Dinosaur Paleobiology and it will cover topics in dino biology, as well as evolution, plate tectonics, and extinction. Course material claims it will also help you understand how science works. Go to this site to learn more.

As part of their promotion, the University of Alberta put together this fun page: Dinosaur Videos: 12 dinosaur myths that will blow your mind. I don’t know how these myths will actually “blow your mind” or even if that is something you want done to your mind. (I know, that silly title is just tedious click-bait.) But the webpage itself is not bad. Each myth is accompanied by a short video. If you aren’t jumping over to their site, here are three of the best of the U of A  blow-your-mind myths:

  1. Dinosaurs walked the earth, then mammals came. That’s a myth. Mammals actually evolved before dinos, but stayed in a repressed rat-like stage until the dinosaurs cleared out. Synapsids, of which mammals are the major modern representatives, arose 324 million years ago. They became rather large and dominant creatures until the Permian extinction, after which most were wiped out – except for the mammal branch. Those animals kept our bloodline alive, but were forced into cowering submission by the rising influence of the dinosaurs. Then, of course, most dinosaurs went extinct while others became birds, clearing the way for the rise of synapsids (as mammals) once again. 

  2. Some dinosaurs lived in water. That’s a myth, too. Even the super-big 100,000-pound fellows like Brachiosaurus and Apatosaurus were landed gentry. Somehow they had enough muscle to hold their bodies upright. (There is a theory that the Earth was smaller and gravity was weaker and that’s how the dinosaurs got so big. The Earth might be expanding, but I don’t think it was that much smaller during dino days.)

  3. Dinosaurs were slimey, featherless creatures. Another myth. According to the University of Alberta dino myth page, “Since the 1990s, paleontologists have discovered species after species of extinct dinosaurs that were covered in feathers. These were flightless theropods that may have used their feathery body coverings for insulation, protection from the elements and as displays for potential mates.

If this sounds like fun stuff to know, you will probably like Dino 101: Dinosaur Paleobiology. I suspect the actual course work will be more rigorous and challenging than this fun little introduction (and it might not blow your mind), but chances are it will teach you everything you ever wanted to know about dinos.

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The Greatest Science Quotes

Do you mentally collect and muse over science quotes? Some reasonably good web sites have already done this, but so far none of those sites has my all-time favourite. It’s obscure. It was spoken by a geophysicist fifty years ago and it is mostly lost to the annals of history. But it is worth resurrecting.

I will dash through a few of my runners-up before I get to the best of the best quotes (as defined by me, though my thoughts are open to revision). The following small group of also-rans have been adjudicated as superior only through my own myopic lenses, but you have likely seen them before. And some have the fun attribute of being fake.

Fake? The greatest quotations are attributed to people who may have never voiced the words. Carl Sagan’s reference to our planet as a pale blue dot is stirring and poignant – and because we have this video, we know for certain that he actually said it. But I like this one, too, which is also attributed to Sagan: “Somewhere, something incredible is waiting to be known.” This pithy statement reflects Sagan’s life – motivated by curiosity, seeking the unknown. It should be a guiding aphorism for all of us. It would be my favourite Sagan apothegm, but it was likely penned by journalists who wrote a Newsweek cover story about Carl Sagan. He probably never said it.

Similarly, Einstein is credited with “Everything must be made as simple as possible. But not simpler.” For those of us who aspire to write about science, culture, and history, these words serve as a fundamental maxim. Scientists do well by following this simple philosophy – but not any philosophy that might be simpler. It sums up Occam’s Razor – the preferred theory amongst any two is the simpler theory. Einstein certainly would have agreed with the simple statement, but there is no record that he said it. Ironically, the closest he comes is this very wordy version from a 1933 Oxford speech: “It can scarcely be denied that the supreme goal of all theory is to make the irreducible basic elements as simple and as few as possible without having to surrender the adequate representation of a single datum of experience.” A fine thought, but he could have expressed it more simply.

In a letter to his arch-rival Robert Hooke, Sir Isaac Newton gave us another of our great science quotes: “If I have seen further it is by standing on the sholders [sic] of Giants.” We credit this to Newton. But Sir Isaac was repeating an old and well-worn adage, attributed to the 12th century Jewish philosopher Isaiah di Trani: “Who sees further, a dwarf or a giant? …if the dwarf is placed on the shoulders of the giant who sees further? … So too we are dwarfs astride the shoulders of giants. We master their wisdom and move beyond it.” And there were others who said it, even earlier. Here, however, is perhaps a more original Newtonian quotation, one of my favourites: “I don’t know what I may seem to the world, but, as to myself, I seem to have been only like a boy playing on the sea shore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay undiscovered before me.”  The Cambridge library, in a recent Newton exhibit, says that Sir Isaac “is supposed to have remarked” this on his deathbed. Said or unsaid, Sir Isaac Newton lived the quote and it is a great one.

From these dubious yet credible quotations attributed to Sagan, Einstein, and Newton, I’ll add this unsourced succinct witness to scientific progress: “Science progresses one funeral at a time.” This one is attributed to anonymous, though it was undoubtedly muttered by some young assistant professor, growing weary while waiting for the department chair to die. It, of course, belies the deeper sentiment that progress comes only when the defenders of old untenable beliefs finally exit the stage. This, you will find, is one of the main themes in my book, The Mountain Mystery.

As long as I am indulging in unsourced, unproven, and misappropriated science quotes, here are two of my favourite literary science selections. First, from Michael Crichton’s Jurassic Park, mathematician Ian Malcolm tells the scientists who think they have  sterilized their dinosaurs that “Life finds a way.”  Best heard in Jeff Goldblum’s voice, it is a reminder that we can’t control nature, nor can we predict all the variables in our experiments. My other prized literary quote is from Jules Verne. In Journey to the Center of the Earth, 1864, Verne’s protagonist (Professor Otto Lidenbrock) says:  “Science, my boy, is made up of mistakes, but they are useful mistakes, because they lead little by little to the truth.”  Little truths such as “life finds a way,” perhaps.

So, we have Sagan reminding us to be curious, Einstein admonishing simplicity, Newton celebrating childish wonder, Anonymous encouraging patience, Crichton warning caution, and Verne tolerating mistakes. The last one, from Jules Verne, (science progresses through useful mistakes) leads us finally to my favourite scientific quote.

In the mid-1960s, plate tectonics was slowly gaining acceptance as the best idea to explain how geology works. Before tectonics, large-scale geological phenomena (such as mountain ranges) were considered the work of an expanding Earth, or a contracting Earth, or perhaps a complicated system of rebounding geosynclines. At the time, moveable plates of crust were given less credibility than wild ape-men at carnivals. But a small and persistent group of geophysicists resolved the mechanics of plates in motion and guided geologists to accept the inevitable. Among the leaders was a soft-spoken southerner, Jason Morgan.

Morgan’s work was the final bit of research that completed the drift revolution and led to almost universal acceptance of plate tectonics. His was the last dab of polish on the theory.  Jason Morgan became world-renowned for his mathematical description of plate motion. A colleague asked Morgan what he could possibly do about plate tectonics to make an even greater name for himself. “I don’t know. Prove it wrong, I guess.” To me, Morgan sums up the beauty of science in his reply – there is no humiliation in making a mistake; there is honour in proving oneself wrong.

Good scientists expect and accept that their ideas will one day be rewritten or rejected. Science is not dead, not fixed in absolutes, not inscribed in an unerring tome of ideals. One of the most noble things any scientist can aspire to is to take deeply-held truths – especially their own truths – and examine the most fundamental of them closely, even if the result is to “Prove it wrong.”

Posted in History, How Geophysics Works, Philosophy, Plate Tectonics | Tagged , , , | 1 Comment

How the Earth’s Mystery Mineral Got Its Name

We seldom get to see a sample of the Earth’s most common mineral. It resides within the mantle at extreme heat and pressure not found on the surface. We think that the mineral resides within the mantle – we are not sure, but it is a good hypothesis. However, the mineral stays hidden far below the crust, so we can’t be sure until someone goes down there and fetches a piece.

Fifty years ago, a hypothesis was made that much of our planet is composed of a mineral designated MgSiO3-perovskite. Geologists estimate that 70% of the Earth’s lower mantle (670 to 2900 kilometers below us) is made of this one mineral. If true, it means 38% of the Earth’s volume is MgSiO3-perovskite. For 50 years, this probable existence of magnesium silicate perovskite was debated and generally accepted, but since no one had actually held a piece of it in their hands, the International Mineralogical Association could not approve a more catchy name for this most common of all minerals.

According to the Mineralogical Association, a mineral cannot be given a name until there is physical proof of its natural existence. Tests must be performed on an actual physical sample, not an expected theoretical mineral. This, I suppose, is a policy that prevents amateur chemists from concocting imaginary minerals (“some of this, some of that, a little of this, and Presto! – let’s call it Canadaite.”) For 50 years, no one had analyzed hand-held samples of MgSiO3-perovskite. Now there is an identified sample – and the mineral has finally been given a real name.

Australian Tenham chondrite meteorite - black blobs may contain the mystery mineral.

An Australian Tenham L6 chondrite meteorite  – black blobs may contain the mystery mineral that is common in the Earth’s deep lower mantle.

No one picked up the sample on a trip through the center of the Earth. Instead, it dropped out of the sky. Meteors, when they pass through the atmosphere and slam into our planet, are exposed to high pressure and temperature similar to those in the mantle. Scientists examined one of a group of meteorites called the Tenham L6 chondrites which hit near Tenham Station, Queensland, Australia, in 1879. Over 160 kilograms (350 pounds) of this broken-up meteor were recovered. The examined piece shows evidence that the impact pressure was about 240,000 times sea level (24 gigapascal) and the temperature was about 2100 degrees Celsius. These values are remarkably similar to what scientists expect the lower mantle’s environment to be.

Last month, researchers Oliver Tschauner of the University of Nevada and Chi Ma at Caltech reported in the journal Science that their work on the meteorite “concludes a half century of efforts to find, identify, and characterize a natural specimen of this important mineral.” The pair themselves had spent 5 years searching for MgSiO3-perovskite. The two conclusively identified tiny (30-micrometre) blobs of the mineral as the rumored magnesium silicate perovskite. With this positive identification, the material could be given a proper moniker. No, not Canadaite. Nor was it to be called Americium (that name was already taken and applied to element number 95).  Instead, this most common – but most secluded – mineral has been named bridgmanite. “Who?” you ask.

Percy Bridgman with his high-pressure experimental apparatus, around 1915.

Percy Bridgman with his high-pressure experimental apparatus, around 1915.

You might expect that the Earth’s most common mineral would be named for someone who did some amazing science. You would be right. Percy Bridgman is one of those great scientists of whom most of us have never heard. His expertise was the physics of enormous pressures. In 1905, when his machinery broke at his Harvard lab after pressing some material all the way to 3,000 times the Earth’s atmospheric pressure, he redesigned the apparatus and achieved 100,000 times atmospheric pressure. From thousands of experiments on tensile strength, viscosity, compressibility, electric and thermal conductivity of highly squeezed materials, he derived a set of basic equations which others have named the Bridgman Thermodynamics Equations. For this, Percy Bridgman was awarded the 1946 Nobel Prize in Physics.

Bridgman, right, in his Harvard office.

Bridgman, right, in his Harvard office.

Some of the applications of Bridgman’s work worried him. As head of the physics department, he had to sign off on the transfer of Harvard’s cyclotron to the US Army for the Manhattan Project in 1943. The American nuclear bomb project was top secret, so the military told Bridgman that they were taking his machine to St Louis where it would be used to treat wounded soldiers. Bridgman was no dummy. He told the military, “If you want it for what you say you want it for, you can’t have it.  If you want it for what I think you want it for, of course you can have it.” His cyclotron went to Los Alamos (not St Louis) and was used to develop the atomic bomb, not medicinal isotopes, and he knew it. But after the war, Percy Bridgman saw the escalation of Soviet and American warheads as an impending disaster. Along with Joseph Rotblat, Linus Pauling, Max Born, Bertrand Russel, and Albert Einstein, he was one of the 11 signatories of the famous Russel-Einstein Manifesto, signed in Pugwash, Nova Scotia, in 1955. The manifesto called on world leaders to seek peaceful resolutions to international conflict and to find ways to disarm. The original meeting turned into the on-going Pugwash Conferences on Science and World Affairs.

Bridgman was passionate about the philosophy of science and about the way science affects society. In 1927, he wrote The Logic of Modern Physics which had a major and surprising influence through the 1930s and 1940s on the social sciences. Bridgman’s main subject looked at how we know what we think we know. Particularly, he wrote about the methodology of physics. His intended audience included physical scientists. But through Bridgman’s introduction of operationalism, his book had a huge impact on the field of psychology. Operationalism is a variation of positivism, and positivism is the very basic idea that knowledge can only enter the human mind (and science) through observation and sensory experience – there is no role for intuition, introspection, or divine inspiration.

BridgmanPositivism is not a new idea, but Percy Bridgman’s contribution was to move beyond its requirement for direct sensory validation. He included things that can not be directly measured but instead can be described by related elements which are readily observed. A common, everyday example of operationalism is measurement of the fuzzy idea of “health” in terms of empirical things like biomass, heart rate, and the number of trips to the hospital – things that can be counted and measured. From these, one gets a second-hand, but accurate, measurement of “health”.

Similarly, the second-hand, measured side- effects of quantum mechanics and subatomic particles can define quantums and subparticles. This is important because it means that even if something can not be seen and directly measured, it can still be real – it is not the product of intuition, introspection, or inspiration.  And this idea loops back to bridgmanite and geophysics.

Geophysics (like astrophysics) is at an enormous disadvantage compared to chemistry, botany, newtonian physics, and most other sciences. The latter can be subjected to testable, experimental hypotheses. You might speculate that an upside-down seed will still send roots downward, so you experiment – you turn a seed upside-down and observe and measure the root’s growth. You test your guess by designing an experiment and measuring the results. You can’t do this in astrophysics – you can not crash two supernovae together in a controlled experiment. You might simulate your experiment with a computer model, but you can’t possibly include all the parameters you need to get the right answer.

With the Earth, presumptions about the deep interior (including the existence of bridgmanite) have been indirectly confirmed. Ever since Sir William Gilbert deduced that the core is iron and is generating magnetism, up to modern observations that the crust is apparently burnt in places by fixed hot spots, discovering our planet’s inner workings has all been a series of indirect observations, followed by untestable hypotheses about what will never be seen. If a new observation negates an old hypothesis, the old hypothesis is revised or rejected. But there are no direct experiments and very few first-hand facts.

You can see how all this ties Bridgman to the Earth’s most common and most secretive mineral, bridgmanite. Percy Bridgman gave us the tools to experiment with high pressure, creating environments similar to the lower mantle; but he also gave us the intellectual tools to trust the existence of things which we can only know second-hand. Ironically, the International Mineralogical Association says you can not name a mineral until you can prove its existence and hold it in your hands (positivism),  yet MgSiO3-perovskite has been named bridgmanite to honour the man who said that measurable second-hand effects (operationalism) are good enough to prove that something exists – seen or unseen.

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Banana Peel Tectonics

Ig Nobel Laureate Kiyoshi

Ig Nobel laureate Kiyoshi Mabuchi and some bananas

The 24th annual Harvard Ig Nobel Prizes were awarded to courageous trail-blazing scientists who pushed the limits of curiosity and credulity during the past year. Among the winners of the 2014 prestigious momento were a Canadian who won the Neuroscience Prize “for trying to understand what happens in the brains of people who see the face of Jesus in a piece of toast” while the Psychology Prize went to an Australian “for amassing evidence that people who habitually stay up late are, on average, more self-admiring, more manipulative, and more psychopathic than people who habitually arise early in the morning.” In their good company was a group of four Japanese researchers headed by Kiyoshi Mabuchi. That team’s winning Physics paper was Frictional Coefficient under Banana Skin. In other words, they studied the effect of slipping on a banana peel. Equipment included a shoe, a banana, and a linoleum floor. Apparently “polysaccharide follicular gel played the dominant role in the lubricating effect of banana skin after the crush and the change to homogeneous sol.” The elusive coefficient of friction was measured at 0.07. Ah, but didn’t the MythBusters already do that? Perhaps, but Mabuchi et.al. used more math.

The TV guys busted the myth – they found that it is hard to slip on a banana peel. They discovered that the slick underside of a fresh banana skin has some slippery properties, but things don’t get comedic until a pile of over-ripe banana skins are enlisted. To get a laugh, you need old rotten skins stacked like pancakes. Those old peels need to decompose into a soft slimy slippery texture.

If banana peels aren’t inherently slippery, how did they earn their sidekick reputation? And why did Mario’s Kart expel them as infinite point-stealing weapons? The story goes back to 1866 when Carl Frank started importing bananas from Panama into New York City. They were a novelty and sold at the 1876 Philadelphia Expo as if they were corn dogs. Soon people everywhere indulged – and discarded the peels on the street. In those days, big cities were filthy – the whiff of sanitation was not yet in the air. Thirty years later,  civic leaders were admonishing residents that their dirty throw-away habits were leading to broken arms and legs. And very lame vaudeville skits. Litter laws were enacted and trash removal was started, resulting in less hazardous streets. But the slippery-peel comedians thrived anyway.

Although Mabushi et.al. worked out the friction coefficient for soles skidding on peelings, it was actually the MythBusters who gave us a good experimental, qualitative approach. Alas, there are no Nobels (Ig- or non-Ig-) for television stuntmen, regardless their lofty talents and achievements. Nevertheless, experimental and qualitative investigation is closer to the heart of the average geologist trying to understand how rock layers slide atop one another. And that’s where this blog is heading.

Decollement cartoonIn the 50 years since mountain building was recognized as the result of colliding tectonic plates, thrust sheets have been understood in their true context.  As crustal rocks crash together, some wedges slide up and over others. They tend to do this along a décollement, which is a (relatively) slippery zone between different rock types that allows detachment for rock layers that decouple and move independently. You can see how that works in this cartoon. When compressional pressure squeezes this structural model, the slippery-as-a-banana layer slides along the décollement, the weakest link in the system. Layers get stacked, leading to crustal shortening. This phenomenon was first noticed in the Swiss Jura Mountains in 1907. Geologists there speculated that if all the Swiss stacks could be decompressed and returned to their pre-thrusted positions, Switzerland would be the largest (and flattest) country in Europe.

Meanwhile, closer to my Canadian home in Calgary, I can spy a few similarly stacked peaks from my living room window. These mountains were build as the Kula Plate rammed into the North American Plate and rocks folded, detached, and thrust above the plains. But these rocks didn’t break loose and slide without spending a bit of time resisting the urge to move. Just like the shoe on the banana peel, there is a coefficient of friction involved. Turcotte and Schubert, in their book Geodynamics (pp 352-353), do the math for us. In lab tests, the coefficient is about 0.85. But surprisingly, they discover that the addition of water in porous deeply buried rock layers reduces the frictional force to a coefficient of just 0.o6 – almost exactly the same as Mabuchi’s shoe on the fresh banana peel. Granted, the weights and forces get bigger when it involves mountains rather than fruits, but the skidding principle is the same.

A classic thrust sheet - Alberta Canada's Mount Rundle

A classic thrust sheet – Alberta Canada’s Mount Rundle (Wiki CC image)

Posted in Culture, How Geophysics Works, Plate Tectonics | Tagged , , , , , , | 2 Comments

Okotoks, The Big Rock

Okotoks - aka Big Rock

Okotoks – aka Big Rock

A shattered rock as large as a 3-storey house sits in an alfalfa field on the flat Alberta prairie. It is about 30 minutes from my home in Calgary and the rock is more than a little startling, resting out in a big flat open field. The native Blackfoot people considered the out-of-place rock sacred. They called it Okotoks, which means Big Rock. They had a legend that the Creator Napi had offered his robe to the rock but Napi took it back when the weather turned cold and the Creator had a chill. The rock chased Him. Finally (and this part may be just a myth), a bird farted on the rock, knocking it from the sky, allowing Napi to escape. The rock shattered, but remains quite impressive.

Modern geologists tend to doubt the story, but they agree that Big Rock did travel a long way to get to where it is. About 500 kilometres, in fact. The huge boulder rode into southern Alberta, Canada, atop a kilometre-high glacier from Jasper National Park. It was dropped when the glacier melted at the end of the last ice age, about 12,000 years ago. Although the erratic was originally called Okotoks, I’ll call it Big Rock here, to distinguish it from a small city ten kilometres away also called Okotoks, which is named for the rock. Besides, Big Rock is what the travel guides call it.

oko-fractures filled with quartz

Grey, pink, and white fractured quartzite.

Big Rock is a  massive, highly fractured grey, pink, and white quartzite rock with minor dark brown, dark red, and black banding and some minor veins of crystalline quartz.  The monolith is a glacial erratic – a rock carried by glaciers along a glacial train, then deposited upon the prairie when the transporting glacier melted. Big Rock is an apt moniker because it is believed to be the largest glacially deposited erratic in the world.

The local underlying geology is quite different from the extremely large erratic (16,500 tonnes; 9 metres height and 40 metres length) which sits forlorn upon the Paleogene Porcupine Hills Formation (approximately 40 mya), a nonmarine mudstone interbedded with fine- to coarse-grained cross-stratified sandstone and siltstone.  Twenty kilometres to the west, rugged thrust sheets of the Rocky Mountain foothills dominate. Big Rock rests on the flat high prairie at 1144 metres elevation; fifty kilometres west, the Rocky Mountains top 3,000 metres. The nearness of the foothills and the mountain range are significant to an understanding of the location of the rock.

Big Rock’s metamorphic quartzite contrasts significantly with the underlying Paleogene sedimentary formation. Even the first European explorers knew it was out of place. John Hector, the first geologist to study the rock (1863) suspected it had been transported as part of a thrust sheet from the nearby mountains. He was wrong. The nearest Rocky Mountain exposures are limestone and shale, not quartzite. Quartzite rocks similar to Big Rock are found far to the northwest, in Jasper National Park. These were discovered by Eric Mountjoy in 1958. Mountjoy showed that the Big Rock erratic originated in the Cambrian Gog Group (600-520 mya), a metamorphic formation exposed on peaks that Mountjoy examined high above the Tonquin Valley in the national park. The Gog began as sands deposited in a shallow Cambrian sea. The quartz minerals were buried deeply, subjected to heat and pressure, and became quartzite. During the formation of the Rockies, the old Gog Group was lifted and exposed to erosion.

A modern glacial train, photo by Guilhem Vellut cc-by-sa-2.0

A modern glacial train, photo by Guilhem Vellut cc-by-sa-2.0

Eric Mountjoy surmised that a landslide, likely due to destructive ice sheets approximately 15,000 years ago, deposited the exposed quartzite on top of the glacier. That glacier acted like a conveyor belt, transporting the huge quartzite rock 500 kilometres from Jasper’s Tonquin Valley to its present location, near Calgary. Geologists have referred to this glacial activity as the Foothills Glacial Train because it was narrowly confined between the Rocky Mountains to the west and a larger, rigid continental ice sheet to the east. The glacial erratic train melted, leaving a sparse string of similar, but smaller, erratics along a trail from west central Alberta into Montana.

It took about 3,000 years to deliver the rock via the glacial express train and subsequently deposit it on the flatlands. For the next 12,000 years, the Okotoks Big Rock was exposed to harsh prairie climate conditions. Summer heat at times exceeds 40° C while winter temperatures typically fall below -30° C. Rainfall is not excessive, but sufficient to lodge in cracks and widen them through freezing and thawing cycles in spring and autumn. This contributes to the fractures seen on the rock today.

In summary, Big Rock was subjected to a series of geological misadventures which resulted in its present location and condition. The events spanned since the rock’s deposit as sedimentary sandstone in the Gog Formation approximately 600 million years ago, subsequent burial and metamorphosis into quartzite, uplift in a Rocky Mountain thrust sheet about 70 million years ago, and then the landslide which placed it on the glacial train, 15,000 years ago, which flowed southward at a rate of about 100 – 150 metres per year, (typical for an advancing glacier). When the climate exited the ice age cycle, the glacier melted, leaving Big Rock on the open prairie where weathering has led to massive fracturing.

oko-withfieldsThis is almost the end of the (many-million-years-old) story. About 40 years ago a local construction team decided to take a few sticks of dynamite to the rock, intending to use the material on a road. The dynamite was never lit – folks in the nearby town of Okotoks stopped the destruction of their Big Rock. Since then it has become a minor tourist draw. (As in, “What do you wanna do this weekend? I dunno, why don’t we drive down to Okotoks for ice cream and then go out to see the Big Rock.) A nearby parking area was recently built, a trail paved across the field, and a fence placed around the rock. The last time I was there it was a hot Sunday August afternoon and about 15 people were walking around the rock. A few furtive rock climbers were on top, contrary to the posted rules. But it was all good.

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The Colour Blind Geologist

According to Wikipedia, these are green tomatoes. (CC-Wiki via User:Ks.mini)

According to Wikipedia, these are green tomatoes. (CC-Wiki via User:Ks.mini)

I grew up on a truck-garden farm where children were paid to pick strawberries and tomatoes. I couldn’t tell red from green; I was forever poor. My siblings – especially my younger sisters – would pick three baskets for each of mine. And I was penalized for the green ones. It must have cost the family a lot of money – the green berries had to be thrown out. No one suspected I might be colour blind. They thought that I was slow and that I wasn’t paying attention. That may have also been true, but that’s an entirely different issue.

Colour blindness is an inherited defect. I don’t know who among my ancestors was similarly afflicted, but it might have been my maternal grandfather who often wore mismatched socks (though that may also have been an entirely different issue). Six percent of the world’s males have the red-green mix-up (but only about 0.5 percent of females), so it is sex-linked – that is, the genetic deficiency is stowed on a mutated X-chromosome. Girls get two X’s (as in XX); boys have an XY set. Girls, then, have a fallback X chromosome which is almost always healthy. I undoubtedly got my bad gene from my mother, though of 6 male heirs to the family throne, I am the only mutant.

Cama Cat (CCO via Pixabay)

Cama Cat (CCO via Pixabay)

Where did this defect originate and how has it lasted – and spread – throughout most of the world’s population? One theory suggests that red-green colour blindness has an evolutionary advantage. Apparently people such as I can see through camouflage better than ordinary people. According to Nature, we can discern 15 shades of khaki. This might have helped us alert the tribe to nearby lions or kittens, though in today’s world it only helps us spot the odd paparazzi in the bushes. I have a different evolutionary theory, though I hasten to add that I’ve never seen it presented elsewhere, so it is probably wrong. People such as I (and 1/16th of the other males) have proven ourselves useless at fruit picking. We are better stalking game and tossing spears. This could reinforce and promote the division of labour which appears to be nearly universal in every tribe on Earth. Send the useless man out to hunt lions. Maybe he won’t come back. But if he does, he has been assisted by that mutated colour insensitivity. Meanwhile the keener-eyed lady cavefolk harvested the non-poisonous red mountain ash berries.

Seismic wiggles

Seismic wiggles

I never stalked lions. Instead, I am a geophysicist who works with maps and charts. Colour blindness presents problems in this field, too. Fortunately, geophysical work- stations can be tuned to display seismic amplitudes in variations of red and blue, or yellow and black, or some other exotic combination that does not range from dark red to dark green. Depth or time maps can be generated in a similar way that also does not discriminate against the colour-impaired.

However, there are a lot of old geological maps using shades of red and green. I’ve encountered many. I get into trouble whenever dark red bleeds into lighter shades which blur to light green and then dark green. I can’t tell them apart. Here is how Steve Dutch of the University of Wisconsin (Greenbay) describes a set of USGS maps:

“Within periods, colors mostly grade from dark at the bottom to light at the top. The middle color is used generically for undivided periods. For sedimentary units, coloring is as uniform as possible across the map, with a few ad-hoc variations for areas where extra subdivisions are required. The principal exception is that I insist granite is pink on a geologic map and other igneous rocks should be red or orange. Igneous and metamorphic rocks are colored using shades that contrast with other rock units, and vary in usage in the Appalachians (Paleozoic), Midcontinent (Precambrian) and far West (mostly Mesozoic and Cenozoic). Each map has its own color legend.”

I have no idea what this is.

I have no idea what this map is telling us.

Did you see what he wrote? “Within [geological] periods, colors mostly grade from dark…to light.” And, “I insist granite is pink…other igneous rocks should be red or orange.” You might as well have the legend printed in Klingon while you’re at it. I am not accusing or blaming Professor Dutch, of course. He is saying exactly what I heard in Geology 101. These are the standard colours of geology, but such colours are impossible for some us. (My worst university mark was a bare pass in my Mineralogy 212 Lab. There was no way that I could cross the polarized light streams through a thin section of plagioclase without killing a Stay-Puff Marshmallow Man.) But it’s not just me and I am not complaining about this First World Problem simply because I am easily irritated. I am writing this for the estimated 6,000 red-green colour blind geologists and geophysicists in the world. And I have only mentioned geology/geophysics issues one finds in a classroom or office – going into the Precambrian bush as a colour blind field geologist opens a whole other can of DEET.

What to do?

  • There are advocacy and self-help groups for the colour-impaired. I found this website, We Are Color Blind,  and undoubtedly there are others. Unfairly, colour blind folks are not trusted with fighter jets, yet we aren’t compensated for the heartbreak of not being allowed to fly fighter jets. But that’s OK. (In Romania, colour blind people are not allowed driver’s licences – and that is not OK.) However, we are invariably better looking than average and sometimes that’s compensation enough.
  • There are corrective lenses. They even look cool. I may consider the glasses – but they are still rather expensive, though price came down a lot in the past year. At about $350, maybe I could just rent them one autumn. I could be led around the woodlands so I can share in the ooohs and aaahs that I’ve heard about all my life, but have never experienced. It would also be nice to see the difference at traffic lights, too, instead of just remembering to stop when the light on top is brightest (or is it when the light on the bottom is brightest?).
Cool colour-correcting glasses, from EnChoma.

Cool colour-correcting glasses, from EnChroma.

I once worked in an office with several colour-disabled colleagues. Two were geologists, another was a fellow geophysicist. (He often wore tinted sunglasses at his workstation – now I know why.) I had been at that office for about two years. I had learned small tricks that kept my deficiency from introducing glaring errs of judgement. I remembered which rock horizons were red and green on the maps and I spoke about them knowingly. I kept my disability well-hidden. But the team eventually figured out my problem. Not from my maps, but from my mismatched socks.

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