How Supercontinents Form
Supercontinents are colossal landmasses that form when most or all of the Earth's land converges into a single, massive structure. Throughout history, several supercontinents have emerged, with the most recent being Pangea.
Pangea existed approximately 320 to 195 million years ago and was the only continent on the planet, surrounded by a single ocean called Panthalassa. Its predecessors included Rodinia (1.2 billion to 750 million years ago) and Columbia (1.7 billion to 1.45 billion years ago), while Gondwana (600 million years ago) remains a debated supercontinent candidate.
The Driving Force: Continental Drift
Despite their immense size, supercontinents are no match for the Earth's restless interior. Over millions of years, they inevitably break apart—Pangea being no exception—a process known as continental drift. This involves the constant movement of Earth's tectonic plates.
The theory of plate tectonics, which explains this movement, was developed by Alfred Wegener in the early 20th century. It posits that the Earth's outermost layer, the lithosphere, is made up of several plates that move over the mantle, which comprises about 84% of the Earth's volume.
Heat generated by radioactive decay within the Earth drives these tectonic plates, causing them to shift. As they do, landmasses can either converge, forming supercontinents, or diverge, causing supercontinents to break apart.
Pangea's Legacy
Pangea's breakup resulted in the continents we have today. This is evident in the way the east coast of South America fits snugly against the western coast of Africa, like pieces of a jigsaw puzzle—a testament to their previous unity.
Earth's Dynamic Landscape
Today, Earth's landmasses continue to drift, at an average rate of about 1.5 centimeters per year, comparable to the growth rate of human toenails. However, some regions move faster than others, such as coastal California at about 5 centimeters per year.
When the edges of tectonic plates meet, their movement can cause the Earth's crust to collide and grind against itself, resulting in earthquakes and volcanic eruptions. Mountain formation can also occur as a result of this activity.
The Next Supercontinent
As continental drift is an ongoing process, our current continental arrangement is not permanent. Scientists observe signs of movement towards a different configuration; for instance, there is evidence that Africa is slowly splitting apart. Over millions of years, the continents will likely come together once again to form a new supercontinent surrounded by a single, vast ocean, reminiscent of Pangea's reign.
Summary
Supercontinents form when tectonic plates converge, bringing landmasses together into a single, massive structure. Throughout Earth's history, several supercontinents have emerged and dissolved, with Pangea being the most recent. Continental drift, driven by heat from within the Earth, causes these supercontinents to break apart over millions of years. Currently, the Earth's landmasses continue to drift, and there is evidence of movements that will lead to a new supercontinent in the distant future.