Gondwana: The Great Southern Supercontinent and Its Breakup

Gondwana was a vast supercontinent that joined the landmasses of today’s Southern Hemisphere, together with India and Arabia, for more than 300 million years. It took its full shape around 550 to 500 million years ago, later formed the southern half of Pangaea, and began to break apart about 180 million years ago. The shared fossils and rocks of the southern continents, which make sense only if they were once joined, became some of the strongest evidence for continental drift.

Formation of Gondwana

Gondwana was assembled from older continental blocks during a long series of collisions often called the Pan-African orogeny, which ran from roughly 650 to 500 million years ago. An orogeny is a mountain-building event caused by plates colliding.

Geologists often divide the supercontinent into two parts. West Gondwana included South America and Africa, while East Gondwana included Antarctica, Australia, India and Madagascar. Their final joining, including the Kuunga orogeny along what is now East Africa, India and Antarctica, was largely complete by about 530 to 500 million years ago.

Gondwana formed after the breakup of the older supercontinent Rodinia. It was the largest landmass on Earth through the early Paleozoic, at a time when life was still almost entirely confined to the sea.

Gondwana through the Paleozoic

During the Paleozoic Era, Gondwana drifted across the southern part of the globe and spent long periods over or near the South Pole. That position helped trigger ice ages. A brief but severe glaciation in North Africa, then near the pole, is linked to the Late Ordovician extinction about 445 million years ago.

A much longer ice age, often called the Late Paleozoic Ice Age or Karoo glaciation, lasted roughly from 360 to 260 million years ago. Ice sheets covered parts of South America, southern Africa, India, Antarctica and Australia, leaving scratched bedrock and deposits of glacial debris known as tillites.

Between about 335 and 300 million years ago, Gondwana collided with Laurussia, the landmass made of North America, Greenland and northern Europe. This created Pangaea, in which Gondwana formed the southern half. The northern half later came to be called Laurasia.

The evidence that revealed it

Fossils across oceans

The idea of Gondwana grew from puzzling fossil patterns. The seed fern Glossopteris, a woody plant with tongue-shaped leaves, is found in Permian rocks in South America, Africa, India, Australia and Antarctica. Its seeds were too large to be carried across oceans by wind.

Mesosaurus, a small reptile about a metre long that lived in coastal or brackish waters during the Early Permian, is known from Brazil, Uruguay, Namibia and South Africa, but nowhere else. Later, the Triassic plant-eating synapsid Lystrosaurus was found in South Africa, India and China, and in 1969 an expedition including Edwin Colbert found its remains in Antarctica.

When Robert Falcon Scott’s party died returning from the South Pole in 1912, they were carrying rock samples from the Beardmore Glacier area. These were later found to contain Glossopteris fossils, which helped show that Antarctica had once been joined to the other southern continents.

Rocks and ice

Geologists also noticed that rock layers matched across oceans. The Karoo sequence of South Africa resembles rock sequences in South America, India and Antarctica. Glacial striations, the scratches left by moving ice, point in directions that make sense only when the continents are fitted back together around a polar ice sheet.

From land bridges to drift

In the 19th century many geologists explained these patterns with sunken land bridges. In 1872 Henry Benedict Medlicott applied the name Gondwana to a sequence of rocks in central India, and in the 1880s the Austrian geologist Eduard Suess used Gondwana-Land for a former southern landmass, which he thought had partly sunk beneath the sea.

In 1912 Alfred Wegener proposed instead that the continents themselves had moved, an idea explored in the article on continental drift. The South African geologist Alexander du Toit gathered extensive southern evidence in his 1937 book Our Wandering Continents. The theory was accepted only after plate tectonics provided a mechanism in the 1960s.

Gondwana in the age of dinosaurs

Even inside Pangaea, Gondwana kept a distinct character. Its southern position and wide interior gave it different climates and plant communities from the northern lands, and after the end-Permian extinction about 252 million years ago its animals slowly recovered in their own way.

During the Jurassic and Cretaceous, as the land began to divide, southern faunas developed features not seen in the north. Large plant-eating titanosaur sauropods and predatory abelisaurid dinosaurs were widespread in South America, Africa, Madagascar and India. Fossil forests and dinosaur bones found in Antarctica show that the polar south was then free of permanent ice and covered by forests during long periods.

The breakup of Gondwana

Gondwana did not split in one event but in stages over more than 100 million years.

The process began in the Early Jurassic, about 183 million years ago, with huge volcanic outpourings in southern Africa and Antarctica known as the Karoo and Ferrar provinces. From about 180 million years ago, East Gondwana started to pull away from Africa.

Around 130 million years ago, India, still attached to Madagascar, separated from Antarctica and Australia. In the Early Cretaceous, between about 140 and 110 million years ago, South America and Africa drew apart and the South Atlantic Ocean opened.

India separated from Madagascar about 88 million years ago and moved rapidly north, colliding with Asia around 50 million years ago and pushing up the Himalayas. Zealandia separated from Australia between about 85 and 80 million years ago, opening the Tasman Sea.

Australia and Antarctica remained joined longest, separating fully between about 45 and 30 million years ago. The opening of the seaway south of Tasmania and the Drake Passage between South America and Antarctica allowed a current to circle Antarctica, helping the continent to freeze over.

Timeline

• c. 650–500 million years ago: Collisions of the Pan-African orogeny assemble Gondwana.
• c. 445 million years ago: Glaciation on Gondwana coincides with the Late Ordovician mass extinction.
• c. 360–260 million years ago: Ice sheets cover large parts of southern Gondwana.
• c. 335–300 million years ago: Gondwana collides with Laurussia to form Pangaea.
• c. 183 million years ago: Karoo–Ferrar volcanism marks the start of the breakup.
• c. 140–110 million years ago: South America and Africa separate as the South Atlantic opens.
• c. 88 million years ago: India separates from Madagascar.
• c. 45–30 million years ago: Australia completes its separation from Antarctica.

Legacy in living things

The long shared history of the southern continents still shows in their plants and animals. Southern beeches (Nothofagus) grow in South America, Australia, New Zealand and New Guinea, and fossils of them are known from Antarctica. The protea family is found in southern Africa, Australia and South America.

Biologists use the term Gondwanan for groups like these whose distribution reflects the old supercontinent. Some patterns, however, are now explained partly by later dispersal across water, and each case has to be tested with fossils and DNA.

Why it matters

Gondwana shaped the geography, climate and life of the Southern Hemisphere for hundreds of millions of years. Its matching fossils and rocks helped persuade scientists that continents move, and its breakup set the stage for the modern southern oceans and the ice-covered Antarctic continent.