Saturday, March 04, 2006

Of Dams and Breaches

It was apparent to me a few weeks ago that not everyone in the press is in the same boat when it comes to the meaning of the word breach. Is a breached levee a broken levee? Is a levee breached when water flows over it?

Breach is a cousin of the word break. In fact, almost every OED definition for the noun uses some form of the word break. A breached levee is one with a physical break in it. A gap. After a storm, one can look at a breached levee and say something like, "Check out that breach," or "Wow, that's a big breach." When water flows over a levee, we say that the levee is topped. Or at least that's what I say.

A breeched levee is a levee that is wearing pants.

Is a levee a dam? Yes. A levee is a type of dam. When I think dam, I usually think something that cuts across a river at a perpendicular angle. But dam is far more general than that. Levee specifically refers to the type of dam which runs parallel to a river. The first few citations for levee in the OED refer to New Orleans. Indeed, the word comes into English through French (from the feminine version of the past participle of 'lever').

The problem with dike is that it can mean both embankment/levee and ditch/pond. Of course, it's also a quasi-pejorative term for lesbian, but I can't imagine a context in which that meaning is confused with one of the others.

I have absolutely no idea what is meant by a 'dry levee'. I guess I don't really know what/who an American Pie is either.


Anonymous Heath Copeland said...

Interestingly, the geological meaning (an intrusion of magma, usually between rock strata) is almost contradictory - dikes are intended to stop the flow of fluids, and are not formed from them. One could argue, I suppose, that once the intrusion freezes it performs that function by forming a plug to act against further intrusion, but I suspect that in practice further intrusions would still occur at more or less the same place for more or less the same reason - the surrounding strata are probably weakest there, and so the dike does not stop further magama flow. Could a plug properly be called a dike anyway? The failure mode for a plug is fundamentally different (it cannot, as you put it, be "overtopped", for instance).

Post scriptum - our Head of English mentioned your blog, and I enjoyed it enormously. Despite being a Maths/Physics teacher, I am one of our resident pedants.

8:36 PM  

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