PANGEA: BIGGER THAN EVER

Pangea was the supercontinent that existed during the Paleozoic and Mesozoic eras about 250 million years ago, before the component continents were separated into their current configuration.The name was coined during a 1926 symposium discussing Alfred Wegener's theory of continental drift. In his book The Origin of Continents and Oceans (Die Entstehung der Kontinente und Ozeane) first published in 1915, he postulated that all the continents had at one time formed a single supercontinent which he called the "Urkontinent", before later breaking 

up and drifting to their present locations.The single enormous ocean which surrounded Pangaea was accordingly named Panthalassa.There were three major phases in the break-up of Pangaea. The first phase began in the Early-Middle Jurassic (about 175 Ma), when Pangaea began to rift from the Tethys Ocean in the east and the Pacific in the west, ultimately giving rise to the supercontinents Laurasia and Gondwana. The rifting that took place between North America and Africa produced multiplefailed rifts. One rift resulted in a new ocean, the North Atlantic Ocean.The Atlantic Ocean did not open uniformly; rifting began in the north-central Atlantic. The South Atlantic did not open until the Cretaceous. Laurasia started to rotate clockwise and moved northward with North America to the north, and Eurasia to the south. The clockwise motion of Laurasia also led to the closing of the Tethys Ocean. Meanwhile, on the other side of Africa, new rifts were also forming along the adjacent margins of east Africa, Antarctica and Madagascar that would lead to the formation of the southwestern Indian Ocean that would also open up in the Cretaceous.The second major phase in the break-up of Pangaea began in the Early Cretaceous (150–140 Ma), when the minor supercontinent of Gondwana separated into multiple continents (Africa, South America, India, Antarctica, and Australia). About 200 Ma, the continent of Cimmeria, as mentioned above (see "Formation of Pangaea"), collided with Eurasia. However, a subduction zone was forming, as soon as Cimmeria collided.This subduction zone was called the Tethyan Trench. This trench might have subducted what is called the Tethyan mid-ocean ridge, a ridge responsible for the Tethys Ocean's expansion. It probably caused Africa, India and Australia to move northward. In the Early Cretaceous, Atlantica, today's South America and Africa, finally separated from eastern Gondwana (Antarctica, India and Australia), causing the opening of a "South Indian Ocean". In the Middle Cretaceous, Gondwana fragmented to open up the South Atlantic Ocean as South America started to move westward away from Africa. The South Atlantic did not develop uniformly; rather, it rifted from 

south to north.Also, at the same time, Madagascar and India began to separate from Antarctica and moved northward, opening up the Indian Ocean. Madagascar and India separated from each other 100–90 Ma in the Late Cretaceous. India continued to move northward toward Eurasia at 15 centimeters (6 in) per year (a plate tectonic record), closing the Tethys Ocean, while Madagascar stopped and became locked to the African Plate. New Zealand, New Caledonia and the rest of Zealandia began to separate from Australia, moving eastward towards the Pacific and opening the Coral Sea and Tasman Sea.The third major and final phase of the break-up of Pangaea occurred in the early Cenozoic (Paleocene to Oligocene). Laurasia split when North America/Greenland (also called Laurentia) broke free from Eurasia, opening the Norwegian Sea about 60–55 Ma. The Atlantic and Indian Oceans continued to expand, closing the Tethys Ocean.Meanwhile, Australia split from Antarctica and moved rapidly northward, just as India did more than 40 million years earlier, and is currently on a collision course with eastern Asia. Both Australia and India are currently moving in a northeastern direction at 5–6 centimeters (2–3 in) per year. Antarctica has been near or at the South Pole since the formation of Pangaea about 280 Ma. India started to collide with Asia beginning about 35 Ma, forming the Himalayan orogeny, and also finally closing the Tethys Seaway; this collision continues today. The African Plate started to change directions, from west to northwest toward Europe, and South America began to move in a northward direction, separating it from Antarctica and allowing complete oceanic circulation around Antarctica for the first time. The latter of which, together with decreasing atmospheric carbon dioxide concentrations caused a rapid cooling of Antarctica and allowed glaciers to form, which eventually coalesced into the kilometers thick ice sheets we see today. Other major events took place during the Cenozoic, including the opening of the Gulf of California, the uplift of the Alps, and the opening of the Sea of Japan. The break-up of Pangaea continues today in the Great Rift Valley.