Over 100 samples taken at about 15-m intervals in the portion of the Camp Century ice core between 70- and 1360-m depths were analyzed for their Na(+), K(+), Ca(2+) and Mg(2+) contents by atomic absorption spectroscopy. Based on independent stable isotope analyses these maxima occurred over the last third of the Wisconsin glaciation.

February issue includes Appendix entitled Directory of United States Government periodicals and subscription publications; September issue includes List of depository libraries; June and December issues include semiannual index