What's That Sign Say?

As i couldn't find the remote control, i saw a programme on the Canterbury Tales by Geoffrey Chaucer and was interested to see that the tales were written 600 years ago but such was the language different to today that it had to be translated into what we would call an English we can understand today.
It appears that since Chaucer put quill to parchment and wrote about a poor student who 'let fly a fart as loud as it had been a thunder-clap', we have gained the letters J, W, U and V (previously the same letter) and which he never had access to.
We may have 15% more alphabet than Chaucer had 600 years ago but consider the Egyptians who 4000 years ago had no letters and used hieroglyphics and you need to be an expert in Ancient Egyptian to understand what Owl, Foot, Squiggly line meant.  
To make sure that future generations would not go disturbing the Kings in the Pyramids, the Ancient Egyptians put up stark warning of all kinds of horrid things that would happen if we did enter the tombs of the pharaohs but we couldn't understand them and so smashed them open anyway.
What this meanderingly brings us to is the spent nuclear fuel dumps that we are currently planning for not just the UK but all over the World as we build new nuclear power plants.
As the radioactive material will remain dangerous for at least 100,000 years, a 'Keep Out' sign is the absolute minimum but it is extremely unlikely that our descendants will speak any of our languages in 100,000 years and 'Keep Out' will mean as much as Owl, Foot, Squiggly line does to us today or even Chaucer and his 'ferne halwes, couthe in sondry londes'.
We could use the international signs like our symbol for radiation but the Egyptians probably thought that stamping the Eye of Horus on the Pyramid entrance would be enough to warn us thousands of years later that it would be bad news to enter.
Of course if our leaders were not such a bunch Nuclear loving bespawling fopdoodles with farts like thunder-claps it wouldn't be a problem, as Chaucer may have said.