A supercontinent is a single massive landmass made up of most or all of Earth’s continental crust, typically at least 75 percent of it. Throughout Earth’s 4.5-billion-year history, continents have repeatedly drifted together into these giant formations and then broken apart again, in a cycle that takes roughly 500 million years to complete. Pangea, the supercontinent most people learn about in school, is only the most recent example in a long series stretching back billions of years.
How Scientists Define a Supercontinent
There is some debate among geologists about what exactly qualifies. Some set the threshold at roughly 75 percent of Earth’s existing continental crust gathered into one landmass. Others define it differently: a supercontinent must contain most or all of the world’s cratons, which are the ancient, stable cores at the heart of each continent. These cratons are some of the oldest rocks on Earth, and their positions through time serve as the primary evidence for reconstructing where supercontinents once sat.
The distinction matters because smaller groupings of continents have existed throughout Earth’s history without earning the “super” label. Gondwana, for instance, combined South America, Africa, Antarctica, Australia, and India into an enormous landmass, but it’s generally classified as a large continent rather than a true supercontinent because significant land remained separate from it.
Earth’s Known Supercontinents
Geologists have identified several supercontinents in Earth’s past, though the evidence gets hazier the further back you look. The best-documented ones, from oldest to most recent:
- Kenorland (roughly 2.7 to 2.5 billion years ago): One of the earliest proposed supercontinents, made up of what are now the ancient cores of North America, the Baltic region, and Siberia. Its breakup may have lasted hundreds of millions of years, finally scattering its pieces around 2.1 to 2.0 billion years ago. Evidence for Kenorland comes from matching rock sequences and glacial deposits found across these now-distant cratons.
- Columbia, also called Nuna (roughly 1.6 to 1.4 billion years ago): Assembled after Kenorland’s fragments and other continental blocks collided through mountain-building events across the globe.
- Rodinia (roughly 950 to 800 million years ago): Formed through a worldwide series of collisions between about 1.3 billion and 900 million years ago, with nearly all known continental blocks of that era stitching together around what is now North America. Like Pangea after it, Rodinia lasted about 150 million years before breaking apart. Some of its fragments later reassembled into Gondwana.
- Pangea (roughly 325 to 200 million years ago): The supercontinent Alfred Wegener first proposed in the early 1900s. It began rifting apart around 200 million years ago, eventually producing the Atlantic Ocean and the continental arrangement we see today.
Some researchers also point to Pannotia (around 620 to 580 million years ago) as a brief supercontinent that existed between Rodinia and Pangea, though its status is debated. Going even further back, a landmass called Ur, centered on what is now India, may have stabilized around 3.0 billion years ago, making it a candidate for the oldest known supercontinent or “supercraton.”
What Drives the Supercontinent Cycle
Supercontinents form and break apart because of convection in Earth’s mantle, the thick layer of slowly churning rock beneath the crust. Heat from Earth’s core drives this motion, pushing tectonic plates across the surface over millions of years. When plates carrying continents converge, ocean basins between them shrink and eventually close, forcing landmasses to collide and weld together through massive mountain-building events. The Himalayas are a modern example of this process in action, formed by India crashing into Asia.
Geologists describe this process through what’s called the Wilson cycle, which has six stages. It begins with a continent stretching and cracking (think of East Africa’s Rift Valley today). That crack widens into a narrow sea (like the modern Red Sea), then expands into a full ocean basin (like the Atlantic). Eventually, the edges of the ocean basin begin diving back into the mantle through subduction, the ocean shrinks, and the continents on opposite sides collide to form a new supercontinent.
The assembly process involves two possible pathways. In “introversion,” the interior ocean that opened during a previous breakup closes back up, essentially reversing the split. In “extroversion,” the exterior ocean surrounding the old supercontinent closes instead, bringing continents together on the opposite side of the globe. In practice, supercontinent formation involves a combination of both.
How Supercontinents Reshape Climate
A supercontinent doesn’t just rearrange geography. It fundamentally alters Earth’s climate, ocean circulation, atmosphere, and sea levels.
When continents collide to form a supercontinent, the massive mountain ranges created by those collisions accelerate a natural process called chemical weathering. Rainwater reacts with freshly exposed rock, pulling carbon dioxide out of the atmosphere in the process. Less CO2 means less greenhouse warming, so supercontinent assembly tends to coincide with global cooling. The interior of a large supercontinent also sits far from the moderating influence of the ocean, creating extreme seasonal temperature swings, harsh dry conditions in the continental interior, and potentially vast deserts.
Breakup works in the opposite direction. As a supercontinent fragments and the pieces drift apart, new ocean basins open and sea levels rise, flooding low-lying continental edges. Weathering slows because less rock is exposed above water, and CO2 accumulates in the atmosphere. On top of that, breakup is often accompanied by enormous volcanic eruptions called large igneous provinces, which release massive quantities of greenhouse gases. The combined effect pushes the planet toward prolonged warming. After Pangea began rifting around 200 million years ago, measurements from mid-ocean ridge rocks show that the upper mantle beneath the new Atlantic was up to 150°C hotter than today’s average, and those elevated temperatures persisted for 60 to 70 million years.
Sea levels during Pangea’s existence illustrate this pattern clearly. Levels dropped to a low point between about 260 and 180 million years ago when the supercontinent was fully assembled, then rose dramatically during the breakup phase, reaching a peak in the Upper Cretaceous around 100 million years ago.
Effects on Life and Evolution
The supercontinent cycle has shaped the history of life on Earth in profound ways. When landmasses join, previously isolated species suddenly share territory, intensifying competition and allowing migration across formerly separated continents. Ocean circulation patterns shift as seaways close, altering marine habitats worldwide. These disruptions can trigger both extinctions and bursts of new evolution as organisms adapt to radically changed conditions.
When a supercontinent breaks apart, the reverse happens. Isolated continents become evolutionary laboratories where species diversify independently, which is why Australia’s wildlife looks so different from Africa’s. Rising sea levels during breakup phases create shallow coastal seas teeming with new marine habitats. The supercontinent cycle’s influence extends to ocean chemistry, patterns of sedimentation, and global nutrient cycles, all of which ripple through ecosystems.
The Next Supercontinent
The current continents are still moving, and researchers have proposed several models for what the next supercontinent might look like. Two of the leading scenarios come from NASA-supported modeling work. In the Amasia model, Antarctica stays roughly where it is while the other continents converge well north of the equator, closing the Arctic Ocean. This could happen around 200 million years from now. In the Aurica model, all continents merge near the equator about 250 million years in the future.
These projections carry real scientific interest beyond curiosity. The position of a future supercontinent, whether clustered at the poles or straddling the equator, would determine how much sunlight the combined landmass absorbs versus reflects, directly shaping global temperatures. An equatorial supercontinent would absorb more heat and potentially create a much warmer world than one centered near the poles. Climate modelers use these scenarios to better understand how the relationship between land position and atmospheric dynamics has operated throughout Earth’s history.