4 RADIOLOGICAL CLEANUP OF ENEWETAK ATOLL assigned female names in alphabetical order beginning with “‘Alice’’ and continuing clockwise through “Yvonne.” The southern islands were assigned male names beginning with “Alvin’” and continuing clockwise through “Leroy. Subsequently. additional sité numes were assigned to smaller islands and other features. disrupting the original order of assignment. The site names are shown in parentheses in Figure |-4. The spelling used for the island names is that adopted in 1974 by the U.S. Board of Geographical Names as best representing the pronunciations of the driEnewetak. The atoll is approximately 23 by |7 statute miles with the long axis running northwest to southeast. The land surface area totals 1,761 acres or 2-3/4 square miles (Figure t-5). The lagoon has an area of approximately 388 square miles. [ts depth averages 160 feet with a maximum of approximately 200 feet.2-3 There are three entrances to the lagoon: the east channel or Deep Entrance, 180 feet deep. lving between Medren (Elmer) and Japtan (David), the Wide Passage in the south, 6 miles in width: and a 24-foot deep channel called the Southwest Passage. Figures 1-6 through 1-16 provide a pictorial introduction to the islands of the atoll. GEOLOGY Enewetak Atoll was formed by the growth of coral reefs on an extinct volcano (Figure I-17). Coral reefs, and subsequently atolls themselves, consist of limestone which is produced by coral animals (coelenterate polyps), coralline algae, and shelled animals. These living organisms require warm, agitated water and strong sunlight to stay alive. This is particularly important to the coral animal forms since they are attached and can only get food which drifts to them. Corals and other reef builders, including algae, produce limy skeletons which, along with coral rubble, sand and other sedimentary material, are bound together in a rock-like mass by the limy secretions of the coralline algae. This continuous production of fimy skeletons and binding by the algae results in the formation and growth of the coral reefs.+ The rate of growth of coral teefs is relatively faster on the ocean side of the volcanic mass than on the lagoon side because of more nutrition and aeration if the wind-driven water.> Coral may grow vertically at an average rate of one millimeter per year. The rate and direction of growth varies with water depth and ceases completely when the coral is exposed by variances in relative sea level. Such variances are associated with the lowering of ocean levels during periods of glaciation. Thus, the growth rate and morphologyare affected alternately by the submersion and subaerial exposure of the reef. Once the coral colonies reach the surface or are