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You're hiking through the Rockies one day when you hear a low, ominous rumble.
有一天你正試圖徒步穿越落基山脈，這時你聽到一種低沉的、不祥的隆隆聲。
Landslide! Hundreds of tons of rock and soil are careening toward you at enormous speed.
是滑坡!數百噸的巖石和泥土眨眼間向你傾瀉過來。
Fortunately, there's a helicopter nearby and you lift off just in time to escape unharmed.
幸運的是附近的一架直升飛機助你逃出生天，多虧及時及時起飛，才免受這一劫難。
But now you notice something odd.
但你卻注意到了一些匪夷所思的怪現象。
After the landslide has gone by, in its tracks little dainty flowers are still standing.
滑坡過后的地方，小小惹人愛的花朵依然挺拔，
Blades of grass are unbent.
小草的葉子也沒有因此折腰，
How is this possible?
其中究竟有何奧秘？
Before we tell you the answer, here's another question.
揭曉答案之前，先想想另一個問題。
What happens when you drop a book flat onto a table?
如果你將一本書水平扔到桌面上會發生什么？
If you try it, you'll see that the book doesn't hit the table unimpeded, but lands on a little cushion of compressed air.
你會發現書在撞擊桌子的時候并非順利，而是有壓縮空氣形成的緩沖墊阻礙。
If you don't believe us, try putting some little pieces of paper on the table before dropping the book.
如果還持懷疑態度,你大可先在桌上放一些小紙張，然后再將書扔過去。
The whoosh of compressed air escaping will blow them off.
四散奔逃的受壓空氣會嗖的將小紙吹走.
That's the same phenomenon that happens with landslides.
這就如同滑坡現象的原理。
When an enormous sheet of rocks and dirt gets moving, it acts like a solid object.
當巨大巖石和泥土塊移動的時候，它們就像一個固體。
It traps the air underneath it and actually rides downhill on a cushion of air.
將空氣壓在下面的它實際上滾動的時候下面就有了空氣墊。
Strange as it may seem, much of the landslide never touches the ground at all.
盡管聽上去有點怪，但大多數山體滑坡從不會和地面接觸。
Because the cushion of air stays underneath it, the rocks and dirt aren't slowed down by friction much and continue picking up speed as they fall.
由于空氣墊，巖石和泥土并沒有受到摩擦力影響而減速，相反會不停地加速。
Large landslides have been clocked in excess of 100 miles an hour.
規模大的山體滑坡時速超過每小時100英里。
So-could you just lie down and let the landslide whoosh over you?
那么你能躺下來讓滑坡從你身上呼嘯著越過嗎？
No, unless you are about the size of a blade of grass.
這可不行。除非你只有草葉般大小。
People who are bigger than that should keep a helicopter handy.
因此比草葉體積大的人應該隨時讓一架直升飛機在身旁待命。
