Pangea was a singular, massive landmass that incorporated almost all of Earth’s continental crust. Geologists refer to this ancient configuration as a supercontinent, a colossal grouping of land that existed millions of years ago. Its existence represents a specific stage in the planet’s history of continental assembly and dispersal, a cycle driven by forces deep within the Earth. The supercontinent first assembled during the Late Paleozoic Era and persisted well into the Mesozoic Era.
Defining the Supercontinent
The assembly of Pangea was largely complete by the Early Permian Epoch, approximately 299 million years ago, and it began to fracture around 200 million years ago during the Early Jurassic Period. The name Pangea, derived from the ancient Greek words pan (all) and gaia (earth), literally means “all lands.” This vast terrestrial body was surrounded by a single, immense global ocean known as Panthalassa.
Pangea was shaped somewhat like a giant “C,” stretching between the northern and southern polar regions. This distinct shape created a major indentation on its eastern margin, which was occupied by the Tethys Ocean. The Tethys Sea separated the northern and southern portions of the supercontinent for much of its existence.
The Process of Assembly
The formation of Pangea was the result of a geological process involving the convergence and collision of earlier continental units. This assembly was marked by intense mountain-building events, known as orogenies, as the separate landmasses collided. The primary event involved the joining of the southern supercontinent, Gondwana, with the northern landmass, Laurasia.
This immense collision closed the ancient Rheic Ocean, welding the two massive continents together during the Carboniferous period. The impact created the Variscan-Appalachian mountain belt, which stretched across the center of the newly formed Pangea. Remnants of this ancient range can still be seen today in the Appalachian Mountains of North America and the Atlas Mountains of northwestern Africa. The final amalgamation of continental blocks, including the collision that formed the Ural Mountains, completed the supercontinent’s structure by the Early Permian.
The Great Dispersal
The supercontinent’s stability eventually gave way to the forces generated by heat transfer within the Earth’s mantle. Beginning in the Early Jurassic Period, around 200 million years ago, rifting processes initiated the breakup of Pangea. This process, driven by mantle convection, is the underlying mechanism of continental drift.
The initial separation divided Pangea into two primary pieces: Laurasia to the north, which would eventually form North America, Europe, and Asia, and Gondwana to the south, which included Africa, South America, India, Antarctica, and Australia. A rift valley known as the Central Atlantic Magmatic Province began to open between North America and Africa, marking the birth of the Atlantic Ocean. The subsequent fragmentation of Gondwana occurred later in the Cretaceous Period, as South America and Africa began to pull apart.
Proof of Pangea
The scientific understanding of Pangea is supported by multiple lines of evidence. One of the most visually striking pieces of evidence is the “jigsaw puzzle” fit of the continental coastlines. The eastern coast of South America, for example, aligns almost perfectly with the western coast of Africa when the continental shelves are reconstructed.
Fossil evidence provides a second layer of proof, as identical fossils of non-swimming, land-dwelling species have been found on continents now separated by vast oceans. For example, the fossils of the small freshwater reptile Mesosaurus are found exclusively in southern Africa and South America. Similarly, the seed fern Glossopteris is found across all the southern landmasses, indicating they were once a contiguous habitat. Finally, geological structures and rock strata show unmistakable correlation, with mountain chains and rock layers of the same age and composition matching up across the reconstructed continents.