Cascadia's Fault - Jerry Thompson [30]
His idea was that Pangaea had broken apart and that huge masses of land had moved sideways across the surface of the earth, jostling and crashing into each other over millions of years. While others had speculated about the significance of matching coastlines, Wegener had the audacity to put it in writing, making himself an instant lightning rod. Published in 1915, his book The Origin of Continents and Oceans triggered a controversy that was still raging in 1964. If Plafker and Benioff turned out to be right about how that fault in Alaska worked, then the essence of Wegener’s big idea might be right as well.
Wegener’s notion that “tidal friction” and differences in gravity caused by the earth’s imperfect, oblate shape had caused the continental breakup and that huge slabs of the earth’s crust somehow plowed across the ocean floors like ships through pack ice was considered by physicists to be impossible. What on earth—what mechanism—could possibly generate a force strong enough to fracture and move entire continents horizontally? To many it sounded like utter nonsense. The evidence that big land masses had once been joined together, however, was harder to dismiss.
The dominant view among scientists at the time was that the continents had been locked rigidly in place from the very beginning of time as the earth solidified from a molten state. With the interior of the planet gradually cooling, the outer crust began to shrink and slump, to crack and wrinkle like a drying apple’s skin—creating mountains along the way. Others thought parts of the crust rose and fell periodically as if they were floating on a semi-fluid interior.
Most who doubted Wegener were aware of the work of other scientists pointing to fossil match-ups, the remarkable similarities between rock layers on different continents, and the evolution of nearly identical plants and animals on opposite sides of the oceans. They realized that sooner or later there would have to be some way to account for all this. Wegener offered a theory to explain how the various bits and pieces might have fit together, even if he couldn’t say for sure why they had come apart.
He argued that if continents could move downward as the planet cooled and contracted, or even upward—rising slowly as ice ages ended and the enormous weight of glaciers melted away—then they could probably move horizontally as well. Figuring out how and why this happened would be the crucial next step. Even before Wegener published his theory there were reasons to question the orthodox view that the earth was cooling and shrinking. In fact, some researchers already thought the opposite might be true.
With the discovery of nuclear radiation at the turn of the century came the understanding that some elements generated energy all by themselves, that rocks containing these elements deep underground might be pumping out an enormous amount of heat that accumulates faster than it can dissipate into space. If true, then perhaps the earth was heating up rather than cooling. The surface of the planet might actually be expanding rather than shrinking. It might also explain how continents could slide or drift sideways.
Scientists began to speculate that heat generated in the earth’s interior might get trapped beneath the continents. Radioactive elements could be generating enormous “convection currents” of melted rock that would rise from the planet’s white-hot mantle toward the surface, like bubbles in a pot of soup. In fact the soup analogy seemed to make so much sense it was still being taught in