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Before
Gondwanaland was formed the
Earth's continents were moving around. Columbia, Rodinia and Pangaea. |
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200m
years ago, when all the continents were clustered together in a “supercontinent”
known as Pangaea. Gondwanaland was the name given to the southern
half of
this landmass, the part that includes modern-day Africa, Australia, South
America, Antarctica and India.
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| Geological evidence suggests that, a billion and a half years earlier, another supercontinent existed. They have dubbed this continent “Columbia”, because some of the best evidence for its existence comes from the Columbia river region. The rest of the map of Columbia is equally hard to imagine. Western Brazil and eastern North America jointly formed a long continental margin where mountain-building occurred. The eastern coast of South America and the western coast of Africa were also joined, just as they are thought to have been in Gondwanaland. |
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Columbia's
formation, but also of its disintegration. The proof of this came from
matching patterns of two pairs of geological rifts in the western United
States and India. In India, the rifts are known as the Mahanadi and the
Godavari; in North America, they are called the Belt and the Uinta. In
both countries, these rifts are about 500km apart. The rifts formed about
1.5 billion years ago. Columbia
began to break up around then. About 500m years later, its pieces reassembled
to form yet another supercontinent, called Rodinia. Geologists believe
that Rodinia disintegrated about 750m years ago and then reformed into
Pangaea after a period of fragmentation that, once again, lasted for roughly
500m years.
Columbia,
Rodinia and Pangaea all have quite similar configurations.
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