The first of these glacial periods is often called the huronian glaciation because it is well exposed in rocks just north of lake huron in southern canada.
第一次冰期称为「休伦冰期」，因其遗迹在加拿大南部休伦湖北方的岩石中清晰可见。
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The early stages of the Huronian, from 2.4 to 2.3 billion years ago, seem to have been particularly severe, with the entire planet frozen over in the first "snowball Earth".