OK, this sunken fence jazz. I looked at Anu's illustration, and that ha-ha just looks like a wall that has a ditch in front of it.

What are the general features of all sunken fences on earth? If I were to sink a fence in mud--down deep so the little spikes at the top of my fence stuck up out of the mud--would I still have a ha-ha?

Or does a ha-ha have to have a ditch in front of it?

And if I fell down a hill in front of a ha-ha I sure as heck wouldn't laugh--I'd probably get up, dust myself off, and start looking for the Bactine. I, in no way, am getting any kind of reiumbursement for mentioning this product on AWAD.

Best regards,
Wa-Wa What crybabies say when they fall down over a ha-ha

wordwell, the real idea behind a ha-ha is to give the landholder the illusion of unbroken vistas while still keeping out the neighbor's sheep. (see illustration) the definition "sunk fence" is a bit misleading, since
it is only 'sunken' from the one side and wouldn't keep out a field mouse were it not for the ditch.

http://home.mn.rr.com/wwftd/

Imagine you were on the upper side of the ha-ha.. Until you were very close to it, you might not see it.. it would look as the field you were in, and the one the sheep was in were the same..

Now days, zoo's use ha-has all the time to create "fence-less" enclosers for animals.. so in the bronx zoo, from several vantantage points, it looks like the lions, zebras, and antelope all share the same space. Create use of ha-has keeps them seperate, and creates a very natural looking environment! (i bet it frustrates the lions!)

I suspect the San Diego zoo, and other zoo's use the same trick, Philadelphia zoo, and Seattle zoo have in their newest exhibits.