240 DISCOVERY REPORTS 



(< 33-00 °/oo) Equatorial Counter-current (Figs. 42 and 70). The boundary was 

 crossed, off Capo Blanco, but had altered considerably within five days. 



Table XXII. The Peru Coastal Current and the Peru Oceanic Current compared 



Southern boundary and the Cape Horn Current 



Seasonal changes have been used, with fair precision it is believed, to determine the 

 southern limits of the Peru Coastal Current. Surface temperature on the west coast, 

 from 8 to 47° S, declined with advance of winter, in all but the parallels of 34-39° S 

 (Table IX). This anomalous rise becomes intelligible on the hypothesis that a former 

 period of active upwelling had existed between these parallels, a hypothesis receiving 

 support from established meteorological facts (pp. 226 and 227). These parallels come 

 under the influence of the Chilean monsoon and after their advent, a cessation of up- 

 welling may be presumed. 



The southern limits of the Coastal Current, identified as the southernmost upwelling 

 centre, is consequently placed in 40° S, within a degree of Mossman's division between 

 cyclonic and anti-cyclonic wind systems. In winter months, however, the southern 

 limit may be as far north as 33° S. It therefore varies with season. Southwards of 40° S 

 surface temperatures show no seasonal anomaly; this has been identified as the Cape 

 Horn Current. 



CONDITIONS ON THE EAST COAST AND WEST COAST COMPARED 



The essential characteristics of the Peru Coastal Current and its wealth of fauna and 

 flora are immediately traceable to the divergence of surface water from the west coast. 

 This is the means by which nutrient salts are brought to the surface, and its importance 

 is made evident by brief reference to conditions on the east coast of South America. 



