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Columbia, also known as Nuna and Hudsonland, was one of Earth's ancient supercontinents. It was first proposed by J.J.W. Rogers and M. Santosh (2002)〔http://szczepan.ct8.pl/teksty/seminar/3.pdf Rogers, J.J.W. and Santosh, M., 2002, ''Configuration of Columbia, a Mesoproterozoic supercontinent.'' Gondwana Research, v. 5, pp. 5–22〕 and is thought to have existed approximately 2.5 to 1.6 billion years (Ga) ago in the Paleoproterozoic Era. Zhao et al. (2002) proposed that the assembly of the supercontinent Columbia (Nuna) was completed by global-scale collisional events during 2.1–1.8 Ga. The Columbia continent consisted of the proto-cratons that made up the former continents of Laurentia, Baltica, Ukrainian Shield, Amazonian Shield, Australia, and possibly Siberia, North China, and Kalaharia as well. The evidence of Columbia's existence is based upon geological 〔 and paleomagnetic data. ==Size and location== Columbia is estimated to have been about 12,900 kilometres from North to South, and about 4,800 km across at its broadest part. The eastern coast of India was attached to western North America, with southern Australia against western Canada. In this era most of South America was rotated such 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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Columbia (supercontinent)」の詳細全文を読む スポンサード リンク
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