🌎🌿 PANGEA and CONTINENTAL DRIFT 👨🔬🦕 Alfred Wegener and Plate Tectonics
Planet Earth is home to oceans and continents.
Oceans are vast expanses of salt water, and there are three of them on our planet: the Atlantic Ocean, the Indian Ocean, and the Pacific Ocean.
Continents, on the other hand, are vast expanses of land: on planet Earth, there are seven continents: Europe, Asia, Africa, North America, South America, Oceania, and Antarctica.
It may seem impossible, but 250 million years ago, these continents were all joined together and formed a single large continent called Pangea, a Greek word meaning "All Earth." More precisely, geologists believe that Pangea formed following the union of two supercontinents: Laurasia, the northern supercontinent consisting of present-day Europe, North America, Asia, and Greenland, and Gondwana, the southern supercontinent consisting of present-day South America, Africa, India, the Middle East, Antarctica, and Oceania.
Pangea was surrounded by a single, large ocean, called Panthalassa, meaning "All Sea" in Greek.
During the Jurassic, Pangea gradually began to break up, giving rise to a phenomenon called "continental drift": the various continents we know today began to slowly drift apart, moving like huge floating rafts, until they settled into their current positions. And even if we don't notice, the continents continue to slowly drift today.
The first to theorize the existence of Pangea and the phenomenon of continental drift was the German scientist Alfred Wegener.
He realized that the fossil remains of some dinosaurs were present in both South America and Africa: but how was it possible that a freshwater lizard like the mesosaur could have swum across an expanse of saltwater as vast as the ocean? If it had, it would have drowned immediately! So how could animals of the same species have lived on two continents so distant? To explain the presence of the mesosaur on both continents, Wegener hypothesized that the two current continents were once a single landmass and that mesosaurs had spread before that landmass fragmented.
The same goes for the glossopteris, a now extinct prehistoric plant that was widespread in both South America and Africa, but also in Antarctica, Australia, and India—all portions of landmass that millions of years ago constituted Gondwana, the southern supercontinent that later formed Pangea by uniting with Laurasia. If these lands had not once been a single continent, Glossopeteris would never have been able to grow in areas as distant from each other as they are now!
And the same goes for Lystrosaurus and Cynognathus, ancestors of mammals whose remains have been found on continents that are now very distant, but that were once joined together.
Wegener also demonstrated how the rocks and glacial sediments of now-separated territories fit together perfectly, thus forming a single large puzzle.
And indeed, you'll notice how South America and Africa fit together perfectly, just like two pieces of a puzzle.
But what was the force that caused continental drift? What are the causes of these movements of the Earth's crust, which continue to this day?
Beneath our feet, the heat released in the Earth's deepest layers causes large portions of the Earth's crust, called plates, to move. This theory, called "plate tectonics," is responsible for various phenomena, including earthquakes, mountain formation, and ocean expansion. Therefore, it was precisely this movement of the Earth's plates that caused continental drift, causing Pangea to split into seven different landmasses and migrate to their current locations.
Now that you know what Pangea is, ask yourself this question: Since the continents continue to shift, could they reunite to form another Pangea? Think about it and let us know in the comments! See you in the next video!
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