Tectonic Plates at 913,000 Kilometres per Hour

long nails

Growth that crawls.

The Earth’s plates move at the same blazing speed as fingernails grow. On average, 2 centimetres in a year. Blink and you won’t miss much. The ox may be slow, but the Earth is patient. In 650 million years, the Earth’s crust moved 13,000 kilometres. Planet-scale wrinkles, rifts, twists, collisions, and mountain ranges are possible with the vastness of time. But the only signs we might witness are some volcanoes and the occasional earthquake. We really can’t appreciate North America’s westward drift – the continent barely budges a meter or two in a lifetime.

To help us grasp the ungraspable, various analogies and visual tricks help us appreciate that plate tectonics happens. One of my favourites is an ever-widening space between some stakes in the ground at the Ontario Science Centre, where one of the leaders of tectonics theory (Tuzo Wilson) worked. One marker shows the continent’s location in 1908, when Wilson was born, the other – displaced a couple metres – shows us how much the marker has moved since then.

Without travelling to Toronto, here is another way to experience the reality of plate tectonics. This video gives us 3,300 million years of motion in 260 seconds. If we assume the rate of motion has always averaged 2 cm/year (not a likely assumption), then the various plates have meandered 66,000 kilometres. We’ll see that happen in about four minutes, with the crust racing around at almost a million kilometres an hour. So hang on:


About Ron Miksha

Ron Miksha is a bee ecologist working at the University of Calgary. He is also a geophysicist and does a bit of science writing and blogging. Ron has worked as a radio broadcaster, a beekeeper, and Earth scientist. (Ask him about seismic waves.) He's based in Calgary, Alberta, Canada.
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1 Response to Tectonic Plates at 913,000 Kilometres per Hour

  1. Athena says:

    Excellent article


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