英语听力:探索发现 2012-10-03 长毛象王国 Mammoth—11(在线收听

 At its maximum, the ice covered nearly six million square miles. And in places, it was up to two miles thick. The ice blanket was punctuated only by occasional islands of rock, the peaks of the very highest mountains.

 
Though Beringia itself remained largely ice-free, it still felt the effects of the ice sheets. Cold, dry air flow down the glaciers and out across surrounding lands. The freezing dry winds blasting off the ice created conditions in which only grasses and other small plants would flourish. There were advantages: the wind also prevented snow from building up so grass remained accessible throughout the year. In such cold temperatures, this was a lifeline for the mammoths, bison and other grazers, which, in turn, sustained other beasts of Beringia.
 
Another widespread Beringian animal that depended on the ice age wind was the dull sheep. Dull sheep needed the snow to be blown clear from their winter grazing. And today they have the same priority. They are found only on the most exposed and wind-swept mountain slopes. In the autumn, dull rams, like the mammoths and the mask oxen, become focused on the urge to mate.
  原文地址:http://www.tingroom.com/lesson/yytltsfx/2012/244836.html