Columbia (supercontinent)

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Columbia (also known as Nuna and, more recently, Hudsonland or Hudsonia) is the name of one of the Earth's earliest supercontinents, which existed approximately 1.8 to 1.5 billion years ago in the Paleoproterozoic Era. It consisted of the proto-cratons that made up the former continents of Laurentia, Baltica, Ukraine, Amazonia, Australia, and possibly Siberia, North China and Kalahari as well. The existence of Columbia is based upon paleomagnetic data.<ref name="Pesonen">Pesonen, Lauri J., J. Salminen , F. Donadini and S. Mertanen (November 2004). "Paleomagnetic Configuration of Continents During the Proterozoic" (PDF). Retrieved on 2006-03-11.</ref>

Columbia is estimated to have been about 12,900 kilometres (8,000 miles) from North to South, and about 4,800 km (3,000 miles) across at its widest part. The east coast of India was attached to western North America, with southern Australia against western Canada. Most of South America rotated so that the western edge of modern-day Brazil lined up with eastern North America, forming a continental margin that extended into the southern edge of Scandinavia.<ref>"New Supercontinent Dubbed Columbia Once Ruled Earth", SpaceDaily, 2002-04-18. Retrieved on 2006-03-11.</ref>

Columbia began to break apart 1.5 billion years ago, the rifts from which have been found in the western United States and India.<ref>Whitehouse, David. "Ancient supercontinent proposed", BBC, 2002-04-25. Retrieved on 2006-03-11.</ref> The rifted fragments formed the supercontinent Rodinia about 500 million years later.