I'm reminded of Japanese tsunami stones: http://www.nytimes.com/2011/04/21/world/asia/21stones.html http://www.nytimes.com/2011/04/21/world/asia/21stones.html

I'm reminded of Japanese tsunami stones: http://www.nytimes.com/2011/04/21/world/asia/21stones.html http://www.nytimes.com/2011/04/21/world/asia/21stones.html They are markers hundreds of years old warning future villagers not to build below certain points (high-water marks for past tsunamis). In some locations they are still respected today.