360 LIST ET AL. SAMPLE COLLECTION AND ANALYSIS The samples were taken with two instruments: a “cookie cutter” that removés a 3.5-in.-diameter core to a depth of 2 in. and an orchard auger which cuts a hole the same diameter as the cookie cutter and removes the soil to the desired depth from a beginning depth of 2 in. The cookie cutter is used for the first 2 in. because the auger has a tendency to make a hole larger than its diameter as it cuts through a mat of grass and roots. In all cases, the error in the measurement of the sampled area was ndt greater than 1 or 2%. The sample includes all the vegetation, both living and dead. The final aliquot for analysis includes the proper fraction of vegetation that segregates during sample preparation. Also, all rocks are crushed and included in the analyzed sample. The sample is usually a composite of 20 individual cores. The weight of the sample ranges from 20 or 30 lb for highly organic or peaty soils to as much as 100 lb for samples taken to a depth of 10 in. from dense soils. After the soil was dried, crushed, and homogenized, aliquots of about 1 Ib, identified only by number, were sent to the Health and Safety Laboratory (HASL) for analysis. Two aliquots were sent from each sample, but each member of the pair was sent in a different group to include a time-of-analysis variable. In addition, single blind aliquots of 41 of the soils were also analyzed at the Soil Survey Laboratory of the Soil Conservation Service at Beltsville, Md. The results of the comparison of the two analyses performed on each sample by HASL are shown in Fig. 1, An intercomparison of the HASL and the Soil Survey Laboratory results is shown in Fig. 2. The extraction of the Sr was accomplished by an HCIleach. However, there are unresolved differences between the results obtained by an HCl] leach and by a more complete dissolution of the sample by fusion. The HCl leach values are about 5 to 10% lower than the fusion values. These differences are currently under intensive study, and it is hoped that they will be resolved in the near future. Until that time the reported soil data must be viewed as tentative. Samples collected in the 1963 to 1964 survey were taken toa depth of 8 in. Previous studies‘ have shown (Fig. 3) that virtually all the *Sr is contained in the upper 8 in. of soil. It is also possible to compare the fallout of Sr in the period from 1960 to 1963, as indicated by the soil samples, with that collected by means of pots and ion-exchange columns inthe monthly precipitation sampling network of HASL. At 15 sites the soil samples were taken within a few miles of the precipitation samples and at approximately the same elevation. A comparison of the soil increment with the total observed precipitation deposition over the same interval is shown in Fig. 4. The unlabeled points in the lower portion of the diagram repre-