COLOUR OF THE SEA 175 



The accuracy of Buchanan's observations is confirmed by our own, made inde- 

 pendently, and his notes which describe the water as "green", "chalky green", 

 "olive green" and "ultramarine" express very clearly the colours in Plate XVI. His 

 reference to water of a greenish blue off Antofagasta finds a counterpart in our descrip- 

 tion of it, and the chalky green water found by him off Payta is evidently the same as the 

 colour we met off Salaverry, Punta Aguja and Talara. His terminology is sufficiently 

 accurate to warrant the conclusion that he did not come across the patches of orange, 

 russet brown, and khaki noted in the other sketches. The small distances from the shore 

 at which chalky green water was found by him agree with our own observations ; 5-10 

 miles is his usual limit, but in his note of greenish water at 1 5 miles offshore between 

 Chala and Arica he seems to be describing a hue of ultramarine. 



On no occasion during the present survey were cold patches of blue oceanic water 

 met close inshore as described by Buchanan at Huasco and Carizal. A hypothetical 

 significance has been attached to these cold " blue patches " because they were supposed 

 by him and by certain later writers to indicate the presence of recently upwelled water 

 which, having come from a depth below the layer of active photosynthesis had a minimal 

 phytoplankton content. According to our own observations, the colour of water which 

 appeared to be upwelling close under the coast differed in no remarkable way from the 

 surrounding water; the areas of green, orange, brown, khaki and chalky green all 

 merging gradually, were suffused with the surrounding waters. The one exception to 

 this rule, the line of demarcation between water coloured russet brown and that of 

 porcelain blue off San Lorenzo Island, has already been noted. When we saw the blue 

 we were convinced that we had come upon a "blue patch": closer examination, how- 

 ever, proved that this could not be so, for the blue water was continuous with oceanic 

 water to the west, thus its area exceeded that of the brown water and it was not a patch 

 within the latter. Moreover, the water did not appear to be actively upwelling (see 

 pp. 170 and 2og-io). 



LIFE IN THE CURRENT 



In contrast to the attention that has been paid to the physical aspects of the Peru 

 Current its fauna and flora have been neglected. Darwin (1845), who spent upwards of six 

 months on the coast, makes no reference whatever to the colour of the current or to its 

 marine life. This is surprising in view of its abundance, for it is rich alike in species and 

 in numbers of individuals. More recently the larger animals and especially those of 

 economic importance have aroused interest, but little is known of the plankton, the 

 ultimate source of food of the larger animals and the cause of the colour of the current. 

 During the present survey collections of phytoplankton and zooplankton were made 

 over the whole area, but a detailed account will not be possible until analyses are available 

 and the quantities of the various species have been estimated. In this and the next 

 section, some results are given which suggest possible correlations with the physical 

 and chemical conditions. These notes are of a provisional character and are only given 



