Where did all the sediment go? Where? Where?

In New Scientist's "The Last Word" section this week, a reader has asked the following, quite brilliant, question:

"How long would it take an average cow to fill the Grand Canyon with milk?"

Hopefully another reader will write in with an answer. I won't attempt to myself, as since I don't drink milk, I know little about cow milking. However, my gut feeling is that it would be a very long time since, even for the most profligate cow, the milk would tend to run out of the bottom end of the Canyon some time before it actually filled up.

I wonder why she wants to know? Perhaps she fancies a really big milky bath, like Cleopatra but more so.

I suspect that even if she gets an answer, she won't be able to try it out. The American National Parks Service are very strict on not leaving things in the canyon that shouldn't be there and I think several gallons of milk would certainly fall in this category.

Anyway, on a related note, this is very funny.