Vol. 4] 



Hohuay.—Cold Water Belt. 



273 



somewhat north of Point Conception. In other words, accord- 

 ing- to this chart, the belt of cold coast water along California 

 and Oregon has a very narrow connection with the cold water 

 of the extreme North Pacific. 



The temperatures for the cold belt are not so low as those 

 reported by the Albatross, but the latter were doubtless taken 

 much closer inshore than those used by the British Admiralty. 

 The locality shown in PI. 31 just north of Cape Blanco is marked 

 on the British Charts as having a variation exceeding- 10° during 

 the month of August. This agrees with the belts of varying 

 temperature found by the Albatross in that vicinity and is prob- 

 ably due to alternate bands of the surface water proper and 

 of upwelling cold water from the ocean depths. 



The isotherms of the Deutsche Seewarte chart are repro- 

 duced in PI. 33. They show similar general relations to those 

 indicated in PI. 32, but differ in making the cold inshore belt 

 much shorter and in locating the coldest part of the belt at two 

 widely separated places — San Francisco Bay and the Straits of 

 Fuca, the lowest temperature being shown by the isotherm of 

 14° C. (57° F.) . The latest data available do not greatly change 

 the average temperatures for these points as marked on the 

 German charts. Davidson* gives the monthly averages in the 

 Golden Gate for 12 years of daily observations. The August 

 mean for this period is 59.2°, with 57° the lowest average for 

 any one year. Lower temperatures are reported just outside 

 the bar. 



The corrections to be made in PI. 33, according to the recent 

 Albatross observations, do not consist in a revision of the tem- 

 peratures given for the cold water areas so much as in the locat- 

 ing of much colder areas near Cape Blanco and in more than 

 doubling the entire length of the belt of cold coast water. The 

 occurrence of the coldest water in the vicinity of Cape Mendocino 

 and Cape Blanco has an important bearing on the theory to be 

 offered to account for the belt of cold water along this coast. 



* Davidson, Gen. Bull. Calif. Acad. Sei., Vol. I, p. 354. 



