It was the midcontinental corridor between two massive icesheets—the Laurentide to the west—that enabled the southward migration.
正是两块巨大的冰原之间的半大陆性质的通道——西面的劳伦斯泰德冰原——使人们向南迁移成为可能。
2
For example, as the great icesheets that covered North America during the last ice age steadily melted away, huge volumes of water flowed from them.
例如，随着覆盖北美的大冰原在最后一个冰河时代逐渐融化，大量的水从冰原流出。
3
If you replenish the icesheets and frozen waters of the high latitudes, more light will be reflected back into space, so reducing the warming of the oceans and atmosphere.