lagoon floor. The mean depth of the lagoon is 26.¢ fathoms, with depths between e4 and 32 fathoms most common. that the lagoon floor is Bottom samples and underwater photographs show chiefly covered with Foraminifera, shells, Halimeda debris, coral and other miscellaneous fine debris. In the Marshalls, The slopes the atolls rise out of water about 15,000 feet in depth. of the atolls are steepest in the upper portions near the surface, At Eniwetok the contour gradient reaches a rate of about 4,000 feet per mile. Flgure 3 shows the ocean bottom contours in the vicinity of Eniwetok Atoll. The original native population of Eniwetok Atoll was Micronesian and in 1930 consisted of 121 inhabitants who raised chiefly pigs, chickens and coconuts, and caught the abundant fish available in the Eniwetok area, In 1947 Eniwetok Atoll was selected for an expansion of the permanent Pacific Proving Ground because of its isolated position, stable weather and the geography of 1lts land masses. At this time the Eniwetok people were moved to Ujelang, where nearly 200 natives live today. Since that time Eniwetok has been populated exclusively with Ameri- eee . can personnel associated with atomic test operations. The number of persons present varies from tens of thousands during active operations to several hundreds during interim perlods. The development of the atoll for test purposes has consisted principally of the construction of permanent base camps on FRED and ELMER Islets and of the utilization of the northern islets, Runit to Bogallua, extending from for shot-site and technical instrumentation purposes. 3. GENERAL WEATHER SETTING Although detailed studies of the macroclimate of the Marshall Islands area and of Eniwetok in particular are available in the literature (Appendix III), it was thought desirable to include in this report a general description of the weather setting of Eniwetok. It is the purpose of this section to present a general description that will be especially useful to those not familiar with tropical meteorology. Eniwetok is located on the south side of the Pacific high pressure belt, in What is commonly called the north-east trade wind zone, and to the north of the ne equatorial trough of low pressure, Wind Structure. eS ee a ne ae Ee Eniwetok is overlain with three nearly independent wind ee indication whatsoever of submerged terraces or cliffs on the deep portion of the