compacted to form permanent ice sheets several kilometers thick. 压缩成了几千米厚的永久性冰层

45. Without warm summers to melt them,
    没有了温暖的夏季将其融化
46. snow blanketed the north of the globe...
    白雪覆盖了地球北部
47. ...and, over thousands of years,
    经过数千年
48. compacted to form permanent ice sheets several kilometers thick.
    压缩成了几千米厚的永久性冰层
49. Here, in this silent realm,
    在这个寂静的国度
50. life was frozen out of existence.
    冰冻导致生命无法存在
51. But south of the ice sheets,
    但是在冰层以南

来自《我们星球上的生命 第一季 第八集 Life on Our Planet S01E08 冰与火的世纪》第 48 行