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SNOWBALL EARTH   between ~750 and ~550 million years

Snowball Earth refers to hypotheses regarding paleoclimatic global-scale glaciation, claiming that the Earth's surface was nearly or entirely frozen at some points in its past. The occurrence of Snowball (or Slushball) Earths remains controversial . Proponents claim it best explains sedimentary deposits generally regarded as of glacial origin at tropical latitudes and other enigmatic features of the geological record. Opponents contest the implications of that geological evidence and the geophysical feasibility of an ice- or slush-covered ocean. (click to see all the article on Wikipedia) 

雪球地球 介於 ~7億5千萬到 ~5億5千萬年前

雪球地球指的是一個有關古代氣候的假說,高達全球規模的冰川,造成地球表面在當時幾乎或完全被冰封的。雪球地球(或泥濘地球)的存在與否依舊有爭議。支持者聲稱此假說之最佳解釋為:一般認為在地球初始才產生的沈積礦床,居然在熱帶地區,或其他地質學上不認為會出現的地方被找到。反對者駁斥該地質證據所代表的含意,以及冰或泥覆蓋在海面上,其在地球物理學上的可行性。

(維基連結:雪球地球)

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