0018933 fallout, On the reef shot it appears that the sampling planes were just entering the base of the cloud at the 55,000 foot level since there is a sudden jump in the R-values at this point, The material collected at lower altitudes is depleted in both Sr?9 ana cs)37 and is not greatly different in composition from the fallout at 1000 feet, It is also noted that the enrichment factors for both nuclides go through a maximum with time for the samples from the light and variable stratum, Several conjectures might be offered in explanation of this unexpected behavior with time. One of these is that some sampling may have been dons.at the lower boundary of the light a wariable stratum where some of the particles collected had fallen below the stratu where the rare gases were present. This could also be offered as a possible explanation for the late time rise in the, ge Lo Ire ratio in,the Oak_ shot, Somewhat similar data for the Mo??-to-Kr and Kr 8 to-Kr85 ratios for the first four hours following detonation are given in Table 3,4, Mo?9 to Kr88 ratios are also shown graphically in Figure 3,4, The At the. lower altitudes the Mo?? is enriched and the Kr 88 depleted with respect to Kr85, 1 ! 3. 1,2 Fallout Data, 7 The radiochemical data on the fallout samples may he used to obtain results for the distribution of Sr 0 and Cs!37 which are complementary to those found from the cloud analyses. The fraction of the total Mo?? formed in the explosion which has left the cloud is found by difference from the numbers given in Table 3,2. Multiplication of these figures by the sr?9 and Ce!3? R-values for the fallout and division