Have you ever wondered how long it took for our world to look as it does today? While we now understand that Earth's land masses are constantly moving (albeit slowly), people didn’t know this before the early 20th century. German scientist Alfred Wegener was the first to suggest that the Earth’s continents are drifting, a movement he called continental drift. His belief stemmed from the appearance of the coasts of western Africa and eastern South America, which he thought looked like puzzle pieces that had once fit together and then drifted apart. Upon examination of the appearance of the other continents, he theorized they had once been joined together in a single, massive supercontinent, later named Pangea, which existed from approximately 335 million years ago to 175 million years ago.
These days, scientists know far more about how Pangea broke apart, and how quickly this occurred. While Pangea took millions of years to split up into today’s landmasses, the journey wasn’t exactly leisurely. Tectonic plates experience periods of fast and slow motion. Under extreme stress, they can accelerate at speeds up to 20 times their usual rate. When Pangea broke up as a result of the continent’s inability to resist forces tearing it apart, the tectonic plates eventually sped up to around 20 millimeters per year – which is roughly the same rate as fingernails grow.
Scientists from the University of Sydney and the University of Potsdam utilized computer modeling and seismic data to map the changing speed of plate breakups. The process has been compared to pulling dough apart. At first, pulling apart the dough is difficult because it resists being manipulated and stretched, but the process eventually becomes easier as the dough thins. Scientists believe that the same principle can be applied to drifting continents. Eventually, the connection keeping them together will become too weak to resist forces moving in the opposite direction, and they will break apart.
Retracing Pangea's journey:
- The name Pangea comes from the Ancient Greek words “pan,” which means entire, and “Gaia,” meaning Earth.
- When Pangea started to split, the continents drifted apart from each other at a rate of a millimeter a year. This lasted for approximately 40 million years before a dramatic shift happened. For the next 10 million years, the tectonic plates moved at a very rapid 20 mm a year before they split completely around 173 million years ago.
- When a continent breaks apart, rapid high heat flow and enhanced volcanic activity occur along the margins of the breakup.