You're hiking through the Rockies one day when you hear a low, ominous rumble.
有一天你正试图徒步穿越落基山脉，这时你听到一种低沉的、不祥的隆隆声。
Landslide! Hundreds of tons of rock and soil are careening toward you at enormous speed.
是滑坡!数百吨的岩石和泥土眨眼间向你倾泻过来。
Fortunately, there's a helicopter nearby and you lift off just in time to escape unharmed.
幸运的是附近的一架直升飞机助你逃出生天，多亏及时及时起飞，才免受这一劫难。
But now you notice something odd.
但你却注意到了一些匪夷所思的怪现象。
After the landslide has gone by, in its tracks little dainty flowers are still standing.
滑坡过后的地方，小小惹人爱的花朵依然挺拔，
Blades of grass are unbent.
小草的叶子也没有因此折腰，
How is this possible?
其中究竟有何奥秘？
Before we tell you the answer, here's another question.
揭晓答案之前，先想想另一个问题。
What happens when you drop a book flat onto a table?
如果你将一本书水平扔到桌面上会发生什么？
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.
你会发现书在撞击桌子的时候并非顺利，而是有压缩空气形成的缓冲垫阻碍。
If you don't believe us, try putting some little pieces of paper on the table before dropping the book.
如果还持怀疑态度,你大可先在桌上放一些小纸张，然后再将书扔过去。
The whoosh of compressed air escaping will blow them off.
四散奔逃的受压空气会嗖的将小纸吹走.
That's the same phenomenon that happens with landslides.
这就如同滑坡现象的原理。
When an enormous sheet of rocks and dirt gets moving, it acts like a solid object.
当巨大岩石和泥土块移动的时候，它们就像一个固体。
It traps the air underneath it and actually rides downhill on a cushion of air.
将空气压在下面的它实际上滚动的时候下面就有了空气垫。
Strange as it may seem, much of the landslide never touches the ground at all.
尽管听上去有点怪，但大多数山体滑坡从不会和地面接触。
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.
由于空气垫，岩石和泥土并没有受到摩擦力影响而减速，相反会不停地加速。
Large landslides have been clocked in excess of 100 miles an hour.
规模大的山体滑坡时速超过每小时100英里。
So-could you just lie down and let the landslide whoosh over you?
那么你能躺下来让滑坡从你身上呼啸着越过吗？
No, unless you are about the size of a blade of grass.
这可不行。除非你只有草叶般大小。
People who are bigger than that should keep a helicopter handy.
因此比草叶体积大的人应该随时让一架直升飞机在身旁待命。
