The 5th Graders Got It Right

If you were to ask, say, the kids in Mr. Van Houten’s class, at Lakeshore Elementary School in Eau Claire, Wisconsin, to look at a map of South America and Africa, with the South Atlantic ocean between them, and then ask them what they noticed, it’s likely that after a few minutes one or another student would notice that the two continents seem to fit together – the convex bulge of each fitting neatly into the adjoining concave coast.  They might even say that they looked like they were joined together at some point, and that the South Atlantic ocean found a way to come between them.

By the early 1960s, what most elementary school kids knew for certain about this theory of continental drift, or plate tectonics, was, in fact, NOT the received wisdom among the classical geologists of the day.  In fact, the few “fringe” geologists who dared to put forth the notion that our earth’s continents had been connected in the past were termed “drifters,” and at the few universities that humored their lectures, they were introduced with eyes rolling.  

Here’s the first of a several-part posting on this theory of continental drift, based on a Galapagos-harbor visit we had with my college roommate Dana Yoerger.  Dana is one of the scientists on the Woods Hole Oceanographic Institution’s research vessel Atlantis, anchored here in Puerto Ayora on the eve of an expedition to the Galapagos Spreading Plate, just 350 miles northwest of where Grace is anchored.  He and I went to MIT together; he went onto a career at the three-part intersection of science, engineering, and tinkering --  pursuing a passion that was evident even in the late 70s when we were in school together.  I went onto a career in BS and politics – for which I too had a passion for as a student.  I’m sailing a little boat; Dana is a lead researcher on a 200+ foot vessel of unimaginable sophistication.  

First, we review 4 basic features of plate tectonics; then in the next post, we talk about Atlantis and the tech toys, including Alvin, the deep-sea submersible that discovered the Titanic.  Dinner before dessert.  

1. Mountains – then Mountain Ranges!  Before the mid-60s, the existence of mid-ocean mountains was well-known, a result of the laying of the  trans-Atlantic telephone and telegraph cables.  Over the years, more and more of these mid-ocean mountains were noticed, and one day, it became clear that the mountains in fact formed a chain – similar to the Rockies or Appalachians – and stretched for thousands of miles.  Then scientists supposed that this and similar chains, or ridges, in other oceans, were formed in the same way as the Rockies or Appalachians:  by an uplifting of the earth, like a flat-lying piece of aluminum foil might form ridges if pressed together from both ends.  

2.  Magnetism and the Age of Rocks:  On a parallel track, scientists had also begun to correlate the orientation of a volcanic rock formation’s magnetic field with the age of the formation.  Here’s how.  Assume you’re baking a sheet cake, and you mix some chocolate into the vanilla batter.  There will be stripes in the batter, and once in the oven, the cake will bake these chocolate stripes into the form cake.  Now, since volcanic rock contains lots of iron in it, these iron particles will tend to align themselves with the earth’s magnetic field.  Imagine a compass – a piece of iron.  It swings to align itself with the magnetic pole.  So as the volcanic rock – liquid at first – rises and cools, the iron particles within the rock will align themselves with the magnetic pole as well.  

One of the interesting things about the magnetic pole is that it was not always where it is now; in fact, it has wandered considerably over the years.  So if the scientists know where the magnetic pole was, say, 100 million years ago, and then they find volcanic rock whose iron is “pointed” to that spot, then it’s safe to say the rock is 100 million years old.  

3.  Symmetrical Ages:  In addition, scientists studying the formation of certain volcanic mountain ranges had noticed a remarkable symmetry of age between the two sides of the range:  if the mountains are formed by lava flowing up and out, it stands to reason that the oldest lava would be equally spread out far from the center, and the newest lava symmetrically arranged near to the center of the volcanic uprising.  It’s like the cake-maker poured the batter into the center of a round cake pan, while the pan was in the oven – the first part of the pour might make it to the sides of the pan, and the last few drops would settle into the center.   The “age” of each dollop of batter could be determined by measuring its distance from the center.

4.  A Tear in The Earth:  Mid-Atlantic ridges, iron lining up to point to the magnetic pole (wherever it was) and the symmetry of volcanic mountain formation.  By the mid-1960s, a team of scientists had begun to map these mid-Atlantic oceans with a magnetometer – a basically a device that measures the magnetic field of rock.  In one of those eureka moments that every scientist dreams about, they noticed immediately that the age of the rock on either side of the RIDGE was perfectly symmetrical – that is, 5 miles from the peak on either side, the rocks were of identical age.  Not just a single mountain, but the entire ridge.  Aha!  So the mid-Atlantic ridge was not an uplifting (aluminum foil pressed together) as previously thought.  Instead, there was , in fact, a tear in the earth’s mantle running the north-south length of the Atlantic, up through which volcanic activity was creating the entire mountain range.

Now, scientists had known of undersea volcanic activity creating mountains for years.  Most of the islands in the Pacific were formed that way.  But this was volcanic activity on scale no one had ever contemplated:  a continuous line stretching thousands of miles of steady volcanic eruptions, with mountains rising and then settling – one half headed west to North America, the other half headed east to Europe.  The ocean floor had torn apart and was expanding, and the earth’s crust, heretofore considered one solid piece of rock, was in fact fractured like a piece of lake ice in the springtime, each piece headed in its own direction.

Mr. Van Houten’s class can see this clearly in the South Atlantic:  at one time, South America and Africa were in fact connected – connected until the crust cracked, mountains ranges formed, and the two plates began to move apart:  one west, and one east, leaving the south Atlantic and its bifurcating ridge of mountains to fill in the emptiness between.  

The elementary schools and the “drifters” were right, and by the time Dana and I arrived at MIT, the textbooks had all been re-written, and a mad race was on to look for these cracks.  The field of plate tectonics was born, and to his credit, Dana was on the leading edge when he took his first and to-date only job at the Woods Hole Oceanographic Institution, where some of the seminal discoveries took place about how new earth is formed and how continents move apart and together.  

Consilience:  I´m always struck how advances in one area of human endeavor sparek advances in other areas.  E.M. Forster´s epigram, "Only connect" rings especially true. More recently, Edmund Wilson, the famous biologist, writes of this coming together of sciences in his wonderful book, Consilience.   Quickly, plate tectonics became conventional wisdom, and soon thereafter, the biologists began to understand how species’ similarities across continents could occur:  the continents were once connected.  Geologists could understand how rock strata were similar across continents:   they were once connected.  And marine geologists had a vast array of new questions to answer – and they needed tools to explore the deepest parts of the oceans, tools all contained on the research ship Atlantis, now at anchor in Santa Cruz, Galapagos. 

Dana’s degree is in mechanical engineering, so he turned his talents to developing the tools to go deep below the ocean’s surface and to map, in spectacular detail, the places where new earth was being formed.  Along with a few others, they began to design, improve, and perfect a class of deep-sea research vehicles – manned and unmanned – to explore the ocean’s depths.

Next:  The Galapagos Spreading Ridge, why my friend Dana and his colleagues are here, and a first-hand look at the high-tech/lo-tech toys of deep ocean exploration.