The Atlanta Journal-Constitution
THE WORLD, ADRIFT
Did you know that the Earth’s crust is made of separate pieces that have floated or “drifted” across its liquefied inner core, arranging and rearranging various landmasses over the eons? Not so very long ago, hardly anybody had heard that. And many of the the scientists who had heard it didn’t believe it. But that began to change, 110 years ago.
A handful of scientists had proposed over the years that volcanic and tidal forces may have caused continents to be pulled apart or forced together. One powerful piece of visual evidence supporting this: simularities between the east coast of South America and the west coast of Africa. But it wasn’t until Jan. 6, 1912, that German meteorologist and astronomer Alfred Wegener — that’s him at right — presented a theory that Earth had once been a single landmass and the continents had ripped apart from that and then drifted, over millions of years, to their current locations. Wegener would expand his theory, collect evidence and would publish them in a book three years later. Wegener’s theory was not well-received by geologists at the time or most of the scientific community. They attacked his credentials — what would a meteorolgist know about geology, anyway? — and accused him of cherry-picking facts and data from previously published material. But over time, geologists with field experience — especially from Africa and South America — became convinced Wegener was correct. Turns out, the Earth’s crust is divided into huge 60-mile thick slabs of dense rock of various sizes and shapes — that’s what you see in the large map, above. Those slabs float on a layer of superheated mantle, bumping into one another, ripping apart and causing various ripples and whatnot. What we think of continents — landmasses — lie on these plates. So what Wegener called “displacement theory” and what his critics referred to as “continental drift” led to the discovery of these slabs — called tectonic plates — and to what is now called the science of plate tectonics.