ABSTRACT 



The Naval Oceanographic Office conducted an oceanographic survey 

 in the Channel Islands area aboard USNS DAVIS (T-AGOR 5) during 

 September and October 1965. The survey was a detailed environmental 

 study with major emphasis on currents, sound velocity structure, 

 and bottom composition. Physical, chemical, geological, and biological 

 data were collected. 



Seaward decreases in surface temperature and salinity depicted 

 the influence of the cold, low salinity California Current on the 

 survey area. The sound channel was bottom bounded due to the shallow 

 depths, and the sound velocity axis occurred at a depth of 850 meters 

 (2800 feet). Surface duct development was weak and usually restricted 

 to the upper 10 meters (30 feet) . 



Data from repeated Nansen casts at anchor stations revealed 

 temperature, salinity, and sound velocity to oscillate in a sinusoidal 

 manner throughout a day. This oscillation is attributed to a combination 

 of internal waves, tidal forces, and the earth's rotational forces. 



Current data from parachute current drogues, current meters, 

 and computed dynamics showed the San Nicolas Basin to be the center 

 of a counterclockwise gyre. Maximum current speeds of about 25 

 cm/sec occurred around the basin periphery. Lesser speeds existed 

 towards the center of the basin and with increasing depth. Current 

 meters, planted 2 miles northeast of San Nicolas Island, indicated 

 a clockwise rotational water movement produced by the tides. 



Both bottom sediment analyses and bottom photographs showed 

 the survey area to have the same general characteristics as have 

 been observed in previous studies. Fine-grained , green-gray muds 



sions, and somewhat 



r and several in October, 

 s suggested that the 

 er and the second week 



on 

 tment 



