215 Y. LEVY et al. three thin nin Fig. 2. shown in gins SeagieaREE ysure the , studied Nn section »Sition as ation be1 specific a. Figure mC. In ilms and ough the t low cellulose at’_—=s high a time on gwere ‘red by a of alpha ts”’, it is ithin the tributed. t spots” . ribution . . : eagpy thin section c. Note that the high track densities coincide with non-coral material. (c) 1Son ECERE mea concenthan:in . . section : Fic. 5. 30 um thin section (transmitted light) (a) Photomicrograph of thin showing coral Favites virens texture (1) and Bryozoan-like texture (2). (b) Photomicrograph of cellulose nitrate detector at same scale as (a) showing the distribution of alpha-emitters in sections Photomicrograph of cellulose nitrate superimposed on portion of thin section c [different magnification than in (a) and (b)j. Left portion is composed of Bryozoan-like texture which shows manytracks. Upperright portion is coral and lacks -tracks.