"Tsunami Stones" from 600 years ago called high water mark

On Stones in Japan, Tsunami Warnings — Aneyoshi Journal - NYTimes.com

I find this fascinating. Apparently northeast Japan had a similar tsunami many centuries ago, and folks left stone markers saying "do not build your house below this point" and the like. The recent tsunami came within 300 feet of (but did not quite reach) the markers.

Smart, those ancestors. Us current people, not so much.