257 



The deeper circulation may be related to the divergence 

 in surface current pattern which was found to exist in the 

 central part of the bay. Whenever such a divergence exists, 

 subsurface water must be brought to the surface. This might 

 be reflected in lower surface temperatures or higher salinities 

 in the region of divergence, but apparently the rate of up- 

 welling in this area was so slow that in view of the relative 

 uniformity of temperature and salinity conditions normally 

 found in the inshore area, and of the shallowness of the water, 

 the presence of such deeper water was completely disguised. 

 It was often true that whenever a thermocline existed offshore, 

 a similar marked temperature gradient was absent inshore, but 

 because of the probable intensification of vertical mixing as 

 one approaches the beach and the shoaling of the water, it 

 cannot be concluded that the loss of a thermocline necessarily 

 was due to the divergence and its accompanying upwelling. In 

 short, there is no reason to assume that herein lies a mechanism 

 of sufficient velocity by which material from the bottom in the 

 offshore areas, particularly those adjacent to the sludge out- 

 fall, could by brought to the surface and inshore. 



SUMMARY 



Santa Monica Bay, a large crescent-shaped indenture of 

 the coast, is in open communication with the ocean over the 

 continental borderland of southern California, and the character- 

 istics of the water in the bay are mainly controlled by the 

 conditions farther from shore. Protected as they are by the 

 offshore channel islands and the mountains to the north, the 



