Supercontinents
We’ve all heard of Pangaea, the most famous supercontinent ever. I was under the naive impression that Pangaea was how the continents started out and they moved to where they are now (just now realizing how little sense that would make). It turns out that there is a much more interesting story around continental drift.
A supercontinent is loosely defined as an assembly of all or most of Earth’s continental blocks or cratons to from a single landmass. A craton is an old and stable part of the continental lithosphere (crust + mantle). Remember when we learned there were like 6 continental plates and they either slid by each other, collided and buckled into mountains, separated into a rift, or came at each other with one going over and one under? As with everything we learned in elementary school, this was drastic simplification. For example, look at how many cratons make up North America:
To be clear, cratons and plates are not the same thing, and we were technically taught nothing incorrect.
Anyway, let’s start at the “beginning,” whatever that means. Obviously, all of this stuff is theorized, and widely debated. There are a few different theories about all of this stuff so I’m just going to go off of a video I found.
The first ever supercontinent was Vaalbara, consisting of eastern South Africa and northwestern Australia.
Next, add in India and Antarctica and you get the supercontinent Ur, formed over 3 billion years ago.
300 million years later, North America and Eurasia join the party to make Kenorland. This supercontinent was followed by Arctica, Atlantica, Nena, Columbia, Rodinia, Pannotia, Gondwana, Pangaea, and the duo of Laurasia and Gondwana pt. 2. That leaves us with our world today. Here are some pictures of these supercontinents:
Check out this video to see how things changed over the last 3 billion years. If you’re impatient, watch it at 2x speed. After watching you should note which color corresponds to each modern day landmass and then watch again.
As you can see, there’s typically a cycle of a few hundred million years where all the land comes together and splits into a bunch of smaller pieces. So why does Pangaea get all the love?
Of course a big part of it is being the most recent true supercontinent, but I think the other big reason is that we can look at our land today and see how they fit together. My favorite part of the gif below is how India is about to be part of Antarctica until it nopes out of there for south Asia.
Outside of fitting together so easily, we know that supercontinents existed based on fossils, sediment samples, and wildlife. Imagine back when we could have driven from Durham to Morocco in just a few hours. Or, in one of the free-for-all eras, living in a world with dozens of similarly sized continents much smaller than our continents now. Both of these make me wonder how society would be different. But we’re all about facts here, not philosophy.
One implication of a supercontinent like Pangaea I had never considered was the climate in different regions. Land in the middle of the continent would be extremely dry. Rodinia was almost entirely below the equator. When these continents break up, it opens up basins for water to flow into — enough to move sea levels a considerable amount. Some theories even say this drop in water level helped life move from the ocean to land by slowing bringing the organisms closer to the surface.
It may be weird to think of almost all the land on the planet being connected, but we’re really not that far off even today. North and South America are connected, Europe, Asia, and Africa are connected, island hopping from Australia to Asia would be quick and easy, Uncle Rico could probably throw a football from Antarctica to South America, and mainland Alaska is only 55 miles from mainland Russia. Technically, Eurafroamerica is a current supercontinent if you consider Alaska and Russia connected.
If the supercontinent cycle is a thing, what does our future look like? There are a few different theories, and it seems like we are much more sure that there will be a legitimate supercontinent in about 250 years than we are that it will happen any one way.
Here’s one view of how we could go Pangaea → Now →Future.
And here’s a few examples of theorized future supercontinents:
Strap in for a wild ride boys. I’m assuming that Lefko and Adil will figure out immortality, Davis and Mehul will figure a way to fund all the shenanigans we can think of over the next 250 million years, and I’ll just be along for the ride.
