Early in 1958 a woretorium against further testing of nuclear explosions was under consideration, partly in response tc international awareness about the world-wide fallout of radicactivity from nuclear tests by the several nuclear nations. Before the moratorium, however, an intensive series of tests called Operation Hardtack was conducted. Operation Hardtack took place in 1958 both at Eniwetok Atoll as Phase I and at the Nevada Proving Grounds as Phase II, thereby breaking the pattern of alternate testing years at the sites. Between 5 May and 26 July 1958, twenty-two tests were conducted at Eniwetok under Operation Hardtack, Phase I. This one intense period of testing thereby constituted over half of the 43 total tests conducted at the Atoll) over the entire ten years of testing. Following Operation Hardtack, the U.S. moratorium on testing started on 31 October 1958 and was followed in a ’ few days by a U.S.S.R, morator um. nuclear tests at Eniwetok. ints Marked tne ena of ali The intervening 15 years until the present time have allowed some natural restoration of vegetation on affected islands and have provided the time for a tremendous decrease in the residual radioactivity resulting from the tests. | Two islands were altered in this Operation Hardtack, Phase I. The test Koa was a surface explosion on the small island Dridrilbwij (Gene by the U.S. code name). This test removed the island from the Atoll. The other was Test Cactus at the northwest tip of Runit Island (Yvonne by the U.S. code name). crater. This produced a crater nearby and to the Southwest of’ the La Crosse