Paleo Slide Set: Tree Rings: Ancient Chronicles of Environmental Change
Measuring a tree-ring core on a moveable-stage microscope.

Once all rings are accurately crossdated, the ring widths in each sample 
are measured under a microscope on a sliding stage micrometer accurate 
to the nearest 0.01mm, and recorded in computerized data files. 
Other techniques are used to measure ring density and isotopic composition. 
This slide shows a microscope and measuring machine connected to a computer. 
Ring boundaries can be viewed through the microscope. A core on the stage 
of the machine is measured using a hand crank (near end of the stage) 
to move the stage with the core one ring width at a time. Once the 
measurement is made, an encoder converts the movement of the platform 
into a distance signal. The signal is converted into a width measurement, 
and recorded in a file in the computer.

Photo Credits:
Elaine Kennedy Sutherland
U.S.D.A. Forest Service, Delaware, OH