地球的力量 第3集 冰川(13)廣闊的冰原
兩萬年前
this part of America was at the edge of a vast icesheet.
美國的這部分地區(qū)正處于廣闊的冰原。
It covered much of the Northern Hemisphere.
它覆蓋了北半球大部分地區(qū)
In some places, the ice would have towered over any modern skyscraper.
在一些地方，冰層比摩天大樓還高
When it retreated, just as in Yosemite,
當(dāng)它退去，就像約塞米蒂
the ice left behind these boulders and rock smoothed and polished by ice.
冰帶走這些巖石和留下一片平滑光亮的土地
The ice exposed a hard bedrock called schist
冰使一種叫片巖的硬巖床暴露出來
solid enough for sinking deep foundations to support tall buildings.
能挖出足夠堅固的地基 來支撐高樓大廈
Without this bedrock, New York could not have been built so high.
沒有這些巖床，紐約不可能建這么高的樓
The one part of the skyline that dips
大冰原堆積起散沙和沙礫
is the one place where the ice sheet deposited loose sand and gravel,
使一部分地平面傾斜
no good for building towering skyscrapers.
對于建造摩天大樓很不利
