- 43 - statement are the areas of upwelling where surface water is being pushed away from a land mass by the wind and is being replaced by intermediate water. In an area of up- welling, vertical movement is still slow but may be one or two meters a day. Other areas of upwelling are found along current boundaries. Circulation of water in the deep oceqn is also influenced by high submarine ridges which may be comparable in height to mountain ranges on land. The ridges restrict circulation and if circular in shape can create basins of isolated water. There is a need for more information on the circulation of the deep waters of the ocean in order that predictions of the fate of radioisotopes introduced into the sea may be made. Distribution and biological uptake of fallout in the ocean are influenced by the size and solubility of the fallout particles which, in turn, are determined by the size of the detonation and the type of soils (or water) in the vicinity of the detonation. A detonation may be classified, arbitrarily, as large or small, depending upon the height attained by the cloud formed by the detonation. A large detonation is ‘one in which the cloud reaches the stratosphere and the *