英语听力：探索发现 2012-09-12 长毛象王国 Mammoth—2（在线收听）

 By searching for evidence that still survives today, we reconstruct the landscape and the wildlife of prehistoric North America. During the last Ice Age, massive glaciers covered half of North America. But to the far northwest, there was a land that remained free of ice. This land was called Beringia, and it ranged from what we now know as Canadian Yukon and Alaska across to Siberia in the west. North America was only colonized by people around 14,000 years ago, and Beringia is believed to be the starting point from which they spread out across the continent. In this program, we’ll go back to where it all began, what was this wild new world really like when it was still the land of the mammoth. These mountain glaciers in the Canadian Yukon are relics of the great ice sheets that reached their peak some 20,000 years ago.