What If All the Continents Merged Again?

If all the continents merged into one giant landmass, the result would have a vast, brutally dry interior thousands of miles from any coast. We are not just guessing, either. It has happened before: Pangaea existed from about 335 to 175 million years ago, and supercontinents reform on a roughly 300-to-500-million-year cycle, with the next one forecast in about 250 million years.

It already happened: meet Pangaea

Around 335 million years ago, drifting plates jammed nearly all of Earth's land into a single supercontinent we call Pangaea. It hung together until about 175 million years ago, when it began breaking apart into the continents we recognize today.

So a merged Earth is not science fiction. It is a setting our planet has actually lived through, with early dinosaurs walking across land that is now split by entire oceans.

The shape of today's coastlines is a leftover clue. The way South America tucks neatly against Africa is the fingerprint of a world that used to be one piece.

Matching fossils and rock formations on continents now separated by oceans seal the case. The same ancient creatures turn up on both sides of the Atlantic because, back then, there was no Atlantic to cross.

The supercontinent cycle

Pangaea was not even the first. Continents drift together and apart on a slow loop that runs roughly every 300 to 500 million years.

Plate tectonics keeps the conveyor belt running, so the land is always either gathering up or pulling apart. We happen to live in the 'pulling apart' phase right now, with the Atlantic still slowly widening.

Given enough time, that drift reverses and the pieces come back together. It is one of the longest, slowest cycles on Earth.

• Pangaea existed: about 335-175 million years ago
• Supercontinent cycle: roughly every 300-500 million years
• Next supercontinent: 'Pangaea Ultima,' forecast in about 250 million years
• Current phase: continents spread apart

Life on a single landmass

The defining feature would be the interior. Oceans drive rain, and on a giant continent the center can sit thousands of miles from any coast, so moisture almost never reaches it.

That means an enormous core of desert, baking hot by day and freezing at night, with wild weather swings between the two. Pangaea's interior was exactly this kind of harsh, arid wasteland.

Most life would crowd toward the wetter edges near the sea. The deep interior would be one of the most hostile places on the planet, a dead zone the size of several countries.

Sea levels and ocean currents would shift dramatically too, since one giant landmass changes how water circulates around the globe. The single surrounding ocean would behave nothing like the patchwork of seas we have today.

The next one is already coming

Scientists model a future supercontinent sometimes called Pangaea Ultima, expected to assemble in roughly 250 million years as the Atlantic eventually closes back up.

By then the climate and life would look nothing like ours. But the broad outline holds: one great landmass, a deadly dry middle, and most living things clinging to the wetter edges near the coast.

Some models even suggest the interior could grow so hot that mammals would struggle to survive there at all. It is a sobering reminder that the comfortable, spread-out world we know is just one frame in a very long film.

None of this is cause for alarm, since it plays out over a quarter of a billion years. But it does put our maps in perspective. The continents we treat as fixed and permanent are really just slow-moving passengers on a planet that never stops rearranging itself.

A single continent means a single enormous desert at its heart, farther from the sea than any place on Earth today.

Try It Yourself

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Keep reading: when the Sahara was green and how many countries there are. Both go deeper on the same rabbit hole.