near the water surface. Due to rough water and the difficulty of locating ground zero the depth was measured only 135 feet as compared to the later more detailed soundings of 170 feet. Depression measurements of the ground surface were made by preshot and postshot surveys - of heavy concrete gage pads used by Projects 1.7 and 1.8. Figures 5 and 6 show the types of q § | 4 |g T 2 wl Gene len — Janet Cactus westa 25 iP St WESte oy" rn Lr A | N_ 50.000 _| Figure 4 Eniwetok Lagoon stations. concrete pads used by Project 1.7. The 171 station pads extended from the ground surface to a depth of 4 feet. The pads of Project 1.8 extended to a depth of 1 foot. Fathometer Surveys. Holmes and Narver Company, as part of their normal operations, conducted fathometer surveys of all barge shots expected to have an underwater crater. Shots from which crater data were available were Shots Linden, Oak, Yellowwood, Butternut, and Holly. Miscellaneous Data. Tamping configurations of Shots Koa and Cactus are shown in Figures 7 and 8. The inner tank of the Shot Koa configuration was an air space in which the device was 16