266 riiiccrsitii of Califoniia I'ublkations in Zoologij [Vol. l.'i 



The peculiar downward dip of all the isotherms three miles from 

 the shore may mean an intrusion of warmer water flowing parallel 

 to the coast, as previously indicated (see p. 26-1). or it may be due to 

 some other irregularity in the circulation, the cause of which can not 

 readily be discussed here. 



The results of a .similar series of observations in a jilane through 

 a point three miles south of Point Lonia and running perpendicularly 

 to the contours are shown by plate 23, figure 37. The lower isotherms 

 are approximately horizontal from the western portion over deep water 

 to within three miles of the region of shallow water, where they are 

 deflected upward. While the temperature of the upper levels does 

 not decrease so rapidly toward the inshore position as in the case 

 represented by plate 23, figure 36, a similar type of circulation is 

 shown. The presence of the region of shallow water several miles in 

 extent between the inshore position and the mainland would tend to 

 reduce upwelling and thus to reduce the cooling effect. Moreover, the 

 observations were begun at 7 in the morning at the offshore position, 

 and the inshore position was not reached until 1 in the afternoon of 

 the same day. Hence, as the work progressed, the effect of solar 

 radiation in increasing the temperature ma.sked that of upwelling. 



2. ISOIIALINES 



The isohalines shown l)y plate 24, figure 38, are based on a series 

 of salinity observations corresponding to the temperatures shown by 

 plate 23, figure 36. The upward trend of the lower isohalines cor- 

 roborates the evidence derived from the isotherms, of an inshore flow 

 of deep water which is deflected upward as the coast is approached. 

 The lines corresponding to 33..50Vuo a^fl 33.4.5%,, reveal an inward 

 flow below forty meters and an outward flow above that depth. The 

 salinities at the upper levels are low inshore ; and as the distance from 

 the coast increases they approach the higher value corresponding to 

 local conditions beyond the region of upwelling. 



The isohalines shown by plate 24, figure 39, which correspond to 

 the isotherms of plate 23, figure 37, reveal again the same tyjje of 

 cii'culation. The large area of shallow water between the mainland 

 and this inshore position probably accounts for the high surface 

 salinities near the latter area. The high salinities half-way between 

 the offshore and inshore positions are probably due to the order in 

 wliich the (ibservatious were iiinde, as stated above. 



