He theorized that with the use of watercraft, people gradually colonized unglaciated refuges and areas along thecontinentalshelf exposed by the lower sea level.
他的理论是,随着船只的使用,人们沿着因海平面下降而暴露的大陆架逐渐移居到未冻结成冰的区域。
2
It had been assumed that the ice extended westward from the Alaskan/Canadian mountains to the very edge of thecontinentalshelf, the flat, submerged part of the continent that extends into the ocean.