Professional papers. 260-BB. Subsurface geology of Eniwetok Atoll [with list of references], by Seymour O. Schlanger; with sections on Carbonate mineralogy, by Donald L. Graf and Julian R. Goldsmith: Petrography of basalt beneath limestones, by Gordon A. Macdonald; Dating of carbonate rocks by ionium-uranium ratios, by William M. Sackett and Herbert A. Potratz.