quite improbable that summer heating in the face of predominantly south- 

 erly winds (and hence upwelling tendency) can effect thermoclines of such 

 magnititude (see Figure 21). Gunther (1936) showed, in his Figure 17, 

 a warm tongue advecting from the ocean Pacific into the region south of 

 Arica, about 100 n. miles north of Iquique. It is likely that the eddy, whose 

 warm branch forms the water mass above the thermocline, is bounded 

 geographically to this area because of the abrupt change in the direction 

 of the coast line at Arica. 



The depth of the thermocline, defined as the top layer of rapid temper- 

 ature change, is given in Figure 19. The thermocline depth deepens sea- 

 ward and southward indicating that the warm branch of the eddy is south 

 of the approximate line drawn WNW of Iquique at this time. 



22-0815 

 le VIII 54 

 70.7 



20-0710 

 17 VIII 54 

 69.4 



See ?lKure 3 for Key 



Figure 22. Bathythermograph Traces. 



Summary and Recommendations 



The surface boundary between the Peru Current and Equatorial Counter 

 Current was located by the bathythermograph at north of Cabo Blanco and 

 the subsurface northern extension of the Peru Current was thought to 

 extend as far north and near shore as the Isla La Plata, Ecuador. The warm 



64 



