NavList:

Geoffrey,

Sorry if I missled you about the benchmarks in the USA.  The primary benchmarks are owned and controlled by the US goverment. By law they cannot be damaged or moved.

By our laws, the ownership of land is controled by the physical location of benchmarks even if the recorded coordinates are wrong.  Surveyors must find the marker or monument.  If they note that the recorded location is incorrect they summit the data to the Dept. of the Interior.  This is not an ad-hoc system but set down by regulation.  The USA is a large, new country and was peopled very rapidly.  The goverment had to hire surveyors to map out great areas of land very quickly so the land could be sold.  Some of the people that did the work were not very good and the benchmarks they set were not where they said they were but once the marker was accepted it was " set in stone ".  It, the marker, became the legal point for land ownership - not the recorded location.

When surveyors find a damaged benchmark or monument they sometimes, for public service, ask permission from the goverment to re-set the marker.  The work is only done by professonal, licesenced surveyors and only with the direct permission of the goverment.  They also record the new, correct location.

John H.