Variations of oxygen isotopes in the Camp Century ice core (with
changes from a smoothed curve set off in black), going back 14,000 years.
Higher temperatures to right. (Difference of isotopes
in parts per thousand graphed against years Before Present.)
Below: In the ice trench.
Viewing a section of core, 1964. Compare the picture here of the 1989-92 GISP trench.
Graph from Dansgaard et al., chapter 3 of Karl K. Turekian,
ed., The Late Cenozoic Glacial Ages,
copyright © Yale University Press, 1971. Photo by David Atwood, U.S.
Army-ERDC-CRREL
(Cold Regions Research and Engineering Laboratory), courtesy
Herb Ueda.