I've been working my way through documentaries on various subjects as research for my Punk series and one of the things that keeps coming up is that you can't date monuments. You can date the last organic stuff inside them like food left overs and you can date when the stone was formed but you can't date when it was quarried and used to build the monument.
But I am wondering if this is true. When I was doing my MRes there was a technique that dealt with exposure dates - in this case sand dunes but I know it has been used for other things. If I recall correctly when a cosmic ray hits the surface it can cause little explosions which leave scars called tracts which can be counted. The number off them combined with the rate of cosmic rays hitting the surface gives you how long they have been sitting on the surface.
Now there is a similar thing that happens due to probability and atomic decay within rocks but you can tell the difference.
I can't remember all the specifics but it does seem to me that this could be used.
Obviously there would be issues such as open cast mining or quarrying could leave rocks on the surface for 1000s of years before building occurs but I think most builders would have removed weathered sides of blocks to make them look nice. Then there are issues over rock type - are different types more susceptable to the tracts forming? What if it is a composite material made of fossils and rock fragments?
Some monuments no longer have their outer layers such as the giant pyramid in Egypt so you would get a mixed date of = quarried date - time spent under cladding + time since cladding was nicked or disappeared.
But I can't see these as being worse than the issues surrounding migrating dunes. the dating of these structures would be very important for sorting out our own history and how civilisations have come to be etc...
There maybe more issues with dating like if it can only give dates accurate to 1000s when you need 100s or 10s of years or them only being relative to other techniques but I think it would add an extra layer to what we know.
Now obviously I have been out of the science world for years now and can't even remember what the names for all this sort of stuff is and I am not an archeology expert so maybe these are already being use or rejected or what ever and it just hasn't filtered through to the books and documentaries I am getting my hands on.
However I thought I would share my idea just incase - plus people may suggest other sources of info for me
p.s. having a quick little looky at stuff it would appear there are interesting optical dating methods for minerals that have been exposed to sunlight - surely some of that would be interesting to archeologists. Also another problem with the dating would be how long the monument had spent buried in the ground too!