Michael "Mick" Worthington, Oxford Tree-Ring Laboratory, drilling a core in a ceiling joist.
By measuring the width of the growth rings in the timber, he is able to date the building.
The pencil-sized core is carefully prepared, the tree rings measured, and then the sample
is compared to a master chronology developed for the region (in this case for oak) (1/23/15).
The process provides a date for when the tree was cut; trees were typically cut 6-12 months
before they were to be used for building in order to dry and cure (4/13/15).
