Beautiful Science: Continental Drifts

Every moment the earth literally moves under our feet. The imperceptible shifts of plate tectonics (the Earth’s outermost layer) is the reason for this movement, and the science of plate tectonics offer a breathtakingly elegant explanation of what goes on beneath, in what is known as the theory of continental drifts.

Generations of globe-twirling school children have noticed that South America’s bulge seems to fit into the Gulf of Africa and that Baja California looks as if it had been cut out of the Mexican mainland. These and other subtle clues led German meteorologist, Alfred Wegener in the early 20th century to propose that the continents as we know them were once a single mass.

Wegener’s theory was greeted with catcalls and largely forgotten. How could continents plow through a dense and unyielding oceanic crust? No one, including Wegener, could imagine a force that could cause whole continents to move.  It didn’t help that Wegener was a meteorologist poking his nose into geophysical territory. He would die on an expedition in Germany in 1930, his theory out of favor and all but forgotten. Meanwhile, hints of the earth moving under our feet were everywhere, though they were too small and too vast to be seen. Like ants crawling on the globe, puny humans missed the obvious. It would take powerful scientific tools in the 1960s to reveal the secrets of the earth’s underbelly, tools like sonar tracers, magnetometers, seismographs, and radiometric dating. These powerful tools enabled scientists to trace mysterious ridges running zipper-like along ocean floors, zebra-shaped patterns of magnetic reversals, listen in faint rumblings of shifting plate boundaries, and date geological formations on a scale reaching into deep time.

Tectonic plate boundaries, like the San Andreas Fault pictured here, have been the sites of mountain-building events, volcanoes, or valley or rift creation.

Plate tectonics became established beyond a doubt in the mid-1960s. Contradictions suddenly made sense, and loose ends came together. Continents were now seen as wandering land masses. The Himalayas were recognized as the result of a pushy Indian plate smashing into its Eurasian neighbor, and it became obvious that an ocean was being born in Africa’s Great Rift Valley. Mysteries fell like dominoes before the predictive power of a elegant theory. The skeptics were silenced. Wegener was vindicated posthumously.

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