34 radionuclides in old soils is as follows, in order of greatest : penetration: l Cs 37 sr??, spt? and probably other rare earths. coe? gn°>, or 44 _p, 144 pul?> In the young soils, consisting almost entirely of parent material, the positions of est 3? and spi25 are reversed and the other radionuclides appear to be more completely retained in the surface algal crust. The maxi- mum concentration of fallout radionuclides remains at the soil surface, a few inches or less in depth, except in areas where there has been erosion. In the eroded areas large particles containing both soil algae and radionuclides are randomly distributed to a depth of a few inches. There is some horizontal movement of radionuclides but such movement appears to be very localized and thus is of little consequence in the overall picture of distribution. Csi3? and Sr?9 are the principal radionuclides entering a cycle within the soil-plant system. appears to be small Any loss from this system (a fraction of one per cent per year), but a definite conclusion can not be drawn from the data.