resulting in a density of 1.0. Small samples, spiny lobster hepatopancreas for example, were ashed, dissolved in hydrochloric acid, and sealed in PVC pipe. Oven-dried soil samples were compressed to a densit of 1.35 in PVC pipe. Spectrum resolution was done by Schonfeld's of least squares. (1965) method A set of previously prepared reference spectra for the different geometries and radionuclides was used. All values were corrected for decay to the date of collection. The - error given for individual values is the 95% error. Strontium-90 Analyses Strontium-90 was determined by measuring the equilibrium concentration of its 90 daughter. Yttrium-90 was separated by solvent extraction and precipitation techniques (Petrow, 1965), with stdble yttrium serving as both a carrier and a yield determinant. Recoveries ranged from 80 to 100%. Iron-55 Analyses Iron-55 was separated and purified by a combination of solvent extraction and electrodeposition techniques (Palmer and Beasley, 1967). Recoveries generally exceeded 90%. Counting was done by X-ray spectroscopy with a proportional counter in conjunction with a multichannel analyzer.