164 



DISCOVERY REPORTS 



Fig. 33) described on p. 1 34, and this may perhaps be tropical water and a counter-current 

 (see pp. 161 and 129). The fact that in this section the values of >34-90 °l„^ in the return 

 current did not extend farther away from the land than no miles fit the deductions 

 made in regard to lines of less length, that the return current is a coastal phenomenon. 



CALLAO 



Off Callao the sub-Antarctic water is scarcely recognizable as a distinct layer. Obser- 

 vations at a depth of 60-80 m. at Sts. WS 669, 670 and 671 show a layer where the salinity 

 is rather less than the values on each side, and this together with the comparative homo- 

 geneity of water between 50 and 150 m. are the only signs of a depleted layer. The 

 absence of easily distinguished water layers, together with the warm highly saline wedge 

 coming close to the coast, makes the interpretation of isohalines in Fig. 44 uncertain ; 

 the possibility of their confirming the conclusions drawn from temperature, that sub- 

 sidence is in progress, is discussed on pp. 200-201. 



GUA5JAPE ISLANDS 



The section illustrating salinity distribution off the Guaiiape Islands is typical of 

 upwelling in evenly stratified water, and isohalines resemble isotherms. The com- 

 parative homogeneity of the upper layers may be taken to indicate that the subtropical 

 water has been mixed with the lower layers by upwelling, and that the highly saline 

 warm-water wedge is away from the coast (see Figs. 48 and 16). 



LOBOS ISLANDS 



Salinity here shows even greater homo- 

 geneity inshore, together with greater 

 dilution of the upper layers. In this re- 

 spect the lines off the Guaiiape Islands, 

 Lobos Islands and Punta Aguja make a 

 progressive series (cf. Figs. 48, 47 and 

 46). A layer of slightly more saline water 

 lying at the surface within 50 miles of the 

 shore is shown to have a comparatively 

 high temperature, and it may be supposed 

 to be an eddy. 



PUNTA AGUJA 



Homogeneity in the upper 400 m. is 

 carried even further off Punta Aguja. 

 The appearance of sinking water at 5 

 miles offshore is not shown by isotherms 

 which may perhaps reflect a slow speed 

 of movement. 



STATION NUMBERS _WSe36 

 MILES FROM COAST ' 50 



I 



W5G4I 

 WS543 WSG42 |WSE40 



100- 



2 



z 200- 



300- 



400- 



SOUNDING IN METRE3_ 2277 



Fig. 43. Distribution of salinity. Section off Arica, 

 June 19-20. The position of the section is shown in 

 Figs. 2 and 1 1 ; the corresponding temperature section 

 in Fig. 31. 



