During the Cambrian period, 500 million years ago, worm-like creatures were evolving into fish-like creatures.

在5亿年前的寒武纪，似蠕虫生物逐渐演化成似鱼生物。

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The basement strata and the migmatite, however, were formed much later, about Cambrian period and early palaeozoic era.

但其基底地层和混合岩形成时代较晚，为寒武纪和下古生代。

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Afterward, global large-scale massive volcanic activity in Permian Period generally brought about metamorphism whole middle Cambrian Period volcanic sediment rock in research area.

二叠纪全球性大规模火山活动，致使区内整个中寒武纪的火山沉积岩普遍发生变质。

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"An increase in land plant abundance may have occurred at the time just before the period known as the Cambrian Explosion, when the next Snowball Earth period failed to occur because temperatures did not get cold enough, " he added.

BBC: Earth AP