The following report summarizes a reconnaissance for uranium in Alaska during 1955 that included airborne radiometric traverses, examination of radioactivity anomalies found during the airborne traverses, examination of prospector leads, and examination of areas that seemed geologically favorable for the occurrence of uranium.

The following report covers a reconnaissance for uranium and thorium in Alaska during the 1954 field season that consisted principally of a study of the radioactive beach placers east and west of Cape Yakataga, and ground and airborne radiometric traverses of portions of Kodiak Island and adjacent islands.

Abstract: "Lead-alpha activity age determinations were made on zircon from seven granitic rocks of central and southeastern Alaska. The results of the age determinations indicate two periods of igneous intrusion, one about 95 million years ago, during the Cretaceous period, and another about 53 million years ago, during the early part of the Tertiary. The individual ages determined on zircon from 2 rocks from southeastern Alaska and 1 from east-central Alaska gave results of 90, 100, and 96 million years; those determined on 4 rocks from central Alaska gave results of 47, 56, 58, and 51 million years."

The following report covers analytical work on sedimentary phosphate rock deposits discovered on the Arctic Slope of Alaska during the geological investigation of Naval Petroleum Reserve No. 4 between 1944 and 1953.