Dixon Relic FOUND!!!! Claims age boyond accepted construction of the GP

The Egyptians placed a great value on wood, particularly large timber, as Hanslune mentioned because of a lack of timber in the region.
So finding old wood use is not out of the ordinary and has been identified at many sites in Egypt.
I don't remember which, but there is a temple to a god that was built using timbers from an older structure. We know the temple was built at a certain time because it was documented, but when the timbers were dated they were shown to be 600 years older than the temple.

BTW for a layman's first exploration of dendrochronology I highly recommend Mike Baillie's "Arthur to Exodus".
Professor Baillie goes into the intricacies of dendrochronology and it's use in Egypt to help pin down the timelines.