Paleo Slide Set: Tree Rings: Ancient Chronicles of Environmental Change
Mounted huon pine (Lagarostrobus franklinii) core samples.

After the fieldwork is completed, the cores or cross section samples are returned 
to the laboratory where they are prepared for dating and measuring. Cores are first 
dried and then glued into wooden core mounts. Cross sections are sometimes in pieces 
and may need to be glued together or mounted on a sheet of wood to prevent breakage. 
Cores and cross sections are then sanded using progressively finer grits of sandpaper, 
or trimmed with razor blades, to produce a smooth surface so that the finest details 
of the rings are visible under the microscope. The cores shown in this slide are 
marked with series of dots. The set of three dots represent a century (in this case, 1900), 
and the single dots represent the first year in a decade.

Photo Credits:
Edward Cook
Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY: slides