What was on the other side of Earth to Pangea?

James Tytko investigates...

If you go back 200 to 300 million years ago to the Permian and Triassic periods (which is fairly recent on geological time scales believe it or not) most of the Earth’s landmass was clumped together on one side of the planet, just as you point out. This is known as Pangea, and occurred by chance movements of the tectonic plates which make up the outermost layers of the Earth. Next time you look at a map, look at the West coast of Africa and the East coast of South America: if it looks like they could fit together, it’s because they did!

So, naturally, on the other side of the globe to Pangea was a vast global ocean known as Panthalassa. But what do we know about this huge body of water?

Well, not an awful lot since the oceanic crust underneath Panthalassa was largely subducted. This is a process whereby the denser oceanic crust slides underneath the less dense continental crust as tectonic plates drift into each other over time. This makes it harder for geologists to study.

We can say more about Pangea, where much of the supercontinent is known to have been arid. You can see the red desert sandstones deposited from this time in many places in the UK today.

We can also say that the effect of having one large ocean basin across much of the world, rather than multiple smaller ones we see today, would likely have had a large bearing on deep sea circulation patterns, which are crucial to regulating the global climate and distributing the uneven balance of sunlight which strikes the Earth. That would account for the hotter summer, drier winters, and all round dryness of much of Pangea.

To add to these hostile conditions, 250 million years ago, an eruption of huge volumes of magma in modern Siberia above a hot upwelling plume of material in the Earth’s mantle made the Earth’s climate very hot and unpleasant, and caused the biggest mass extinction in the Earth’s history.

Pangea was eventually broken up by the continents moving apart, and one of the major boundaries along which this happened became the Atlantic Ocean.