268 



University of California Publications. 



[Geology 



changes to changes due to differences in latitude or to distance 

 from the coast line. In the published records of the observa- 

 tions we are not given the time of the day nor the condition of 

 the weather. According to Buchan's discussion of the Chal- 

 lenger observation, the daily variation of the temperature of 

 the surface of the sea does not exceed 1° F. In general the 

 differences considered in this paper greatly exceed that amount. 



The first line of temperatures in the table is but a part of a 

 survey extending from Cape Flattery nearly to Dutch Harbor 

 on the island of Unalaska, made during the latter part of Sep- 

 tember, 1873. The first temperature near shore was 50.4°. In 

 going westward 120 miles and northward about 40 miles, the 

 temperature increased to 59°. From this point the rest of the 

 survey shows a gradually falling temperature, but the initial 

 temperature of 50° was not again reached until the vessel was 

 nearly 1,000 miles to the westward, about 370 miles north of the 

 starting point and only some 200 miles from the island of 

 Kadiak on the Alaska Coast. 



This increase of temperature on first leaving the coast and 

 the subsequent slow decrease are more striking when it is con- 

 sidered that the last records were made two weeks later in the 

 autumn than the first. 



The next eight lines of survey represented in the table ex- 

 tend off shore from 100 to 200 miles. Their lengths are shown 

 approximately in the table where each column represents 15' 

 of longitude. These lines uniformly indicate that the water 

 near shore is colder than that further to the westward along 

 the entire coast from the Straits of Fuca to San Francisco. 

 The lowest temperatures obtained are at Cape Mendocino and 

 Trinidad Head and are at the two stations which are the closest 

 inshore. They are also near the change to the southeast in the 

 direction of the coast line. It is noteworthy that these lowest 

 temperatures are not those found further north. On the con- 

 trary, according to the data now at hand, it is more than 500 

 miles to the northward before surface water as cold as that near 

 the coast between Cape Blanco and Cape Mendocino is reached, 

 during the late summer and the early fall. 



