37 sampling, extruding and sectioning processes. Core sections and surface samples were weighea frozen (wet) and again after 1-2 weeks of drying at 105 C. ad Serer ty npr OT TOE TEEN Ont OPN Eres Dried surface sediments were divided, as is illustrated by the flow diacram in Fig. 6, so that the chemical analysis could proceed independently of radiometric analysis; also, representative samples remained from each station so that sediment particle size or cther types of analyses could be made at a later date. Splitting of the dried sediments was done by removing aliquots from a well-mixed sample which was distributed as evenly as possible over the side of a large beaker tilted horizontally. The size of the aliquots removed for homogenization by grinding was determined by the degree to which a large te variation in sediment particle sizes were present. Many samples were well sorted, either because they consisted predominantly (or entirely) of finely crusned crater debris or natural’y fine-grained materials. Some samples, however, were poorly sorted and contained a large proportion of coarse material. Typically, from 5 to 15 grams of material was removed for grinding, depending on the amount which was estimated necessary to obtain an aliquot representative of particle sizes in the whole sample. Twenty-five to seventy-five gram aliquots of the remaining surface sediments or core sections were similarly prepared in either 2" x 1” or 2" x 1/2" cylindrical polyvinyl chloride containers for gamma spectrum analysis. Sediments not encapsulated for gamma-spectrum analysis, or ground up for other analyses were stored as excess samples. 4.1-1 Total alpha measurements Measurements of the total alpha radioactivity in aliquots of ground surface sediments were made early in the course of the research for the purpose of surveying the concentrations and determining the weight of each rere sediment sample required for the subsequent plutonium analysis. Plutonium