Plate Tectonics

Plate tectonics is the notion that Earth’s crust is composed of a number of huge, interlocking pieces that slowly move. This knowledge is not abstract nor useless in that plate tectonics provides us with insight as to why continents and ocean basins are shaped as they are, why large earthquakes and volcanoes are focused in the geographic patterns in which they are observed, and why Earth has its mountains, folds and faults.

One of the great scientific triumphs of the latter half of the 20th century was the proof and fleshing out of the implications of plate tectonics. This is a concept so grand that it was difficult at first for most scientists to believe it. Indeed, some of the early proponents were ridiculed. Whereas the notion of plate tectonics is a unifying concept, the topic of continental drift is the part of knowledge from which plate tectonics sprang.

In 1598, the Flemish geographer/cartographer Abraham Ortelius noted the “fit” between the Atlantic-fringing continents. In 1620, influential Sir Francis Bacon echoed this as continental coastlines on maps became better defined. Both these scholars left the subject without proposing a causal mechanism. In 1858, Antonio Snider-Pelligrini drew “before” and “after” maps of continents and stated that the continents had moved apart because the biblical flood of Noah restored a lopsided single-continent Earth to a more even configuration with several continents; this reasoning became untenable as scientists found increasing evidence that such a worldwide flood never existed.