Gulf of California — Roden 
43 
SAL. (%o) 
Fig. 18. Distribution of temperature, salinity, and oxygen at 200 m., in February and March, 1939. 
ing, and convective overturn play important 
parts in determining the fertility of any given 
place. Convection is especially conspic- 
uous north of Isla Tiburon and is respons- 
ible for the different hydrographic conditions 
there. Upwelling is largely found in the lee 
of headlands and islands, along the eastern 
coast with northerly winds, and along the 
western coast with southerly winds. Away 
from the shores the Gulf is fertile only in 
spring after considerable winter mixing has 
brought an adequate supply of phosphates 
and silicates to the surface. During the rest 
of the year the surface waters are relatively 
barren. 
The field for investigations in the Gulf is 
nearly unlimited and it is the hope of the 
author that in the future increasing efforts will 
be directed towards the scientific exploration 
of one of the most fascinating seas in the 
Pacific, the Gulf of California. 
REFERENCES 
Allen, W. E. 1923. Observations on surface 
distribution of marine diatoms of Lower 
California in 1921. Calif. Acad. Sci., Proc. 
12: 437-442. 
— 1937. Plankton diatoms of the Gulf 
of California obtained by the G. Allan 
Hancock Expedition of 1936. The Hancock 
Pacific Expeditions , So. Calif. Univ. Pub. 3: 
47-59. 
OXYGEN (ml/L) 
