12 Jamieson and Bingham — Lake Parinacochas. 



Art. II. — Lake Parinacochas and the Composition of its 

 Water ; by George S. Jamieson and Hiram Bingham. 



A sample of water from Lake Parinacochas was collected 

 by one of ns (II. B.) of the Yale Peruvian Expedition of 1911. 

 The analysis of this sample is discussed in the present paper. 



Lake Parinacochas is situated in Peru, between 15° and 16° 

 S. latitude and 73° and 74° longitude, west of Greenwich. In 

 other words, it is about 150 miles JNLW. of Arequipa, and about 

 170 miles S.W. of Cuzco. Its elevation is about 11,500 feet 

 above sea level. It is fed by half a dozen small streams or 

 large brooks, and at present has no visible outlet. In past geo- 

 logical history it was much larger, and had an outlet which is 

 still visible. In a river valley not many miles from the lake, 

 and at a lower elevation, there are a considerable number of 

 large springs which may possibly be fed by the lake. On 

 the borders of the lake are also numerous small springs, 

 which generally occur in swampy hillocks, three or four feet 

 higher than the surrounding plain. The natives told us that 

 in the wet season the lake was higher than in the dry season. 

 The truth of this is evident from the marks of the salt left by 

 evaporation of the lake as it shrinks during the dry season. In 

 general the surrounding region is at present semi-arid, and is 

 inhabited by a pastoral population. Thousands of sheep and 

 some hundreds of cattle feed in the pastures which were for- 

 merly the bed of the lake. There are ruins of villages and 

 agricultural terraces, indicating that at a previous period there 

 was a much larger population here and that agriculture was 

 more common than at present. 



We spent eight days (Nov. 5-12, 1911) in three different 

 camps on the shores of the lake and navigated it in a folding 

 boat, the first boat or canoe that had been seen on the lake, 

 according to the natives. We found that the lake was at pres- 

 ent about 18 miles in length, and 7 miles in width, with a nearly 

 uniform depth at the time of our visit, November, 1911, of 4|- 

 feet. Several hundred soundings failed to show more than 5 

 feet anywhere. Judging by the salt marks on the shore, the 

 lake is probably about a foot deeper in the rainy season. The 

 natives told us that in the dry season the lake sometimes was 

 very much lower than we saw it. The water has had a repu- 

 tation of being brackish for nearly a century, — ever since any 

 one took the trouble to say anything about it in print. The 

 first and only reference to the character of the water that I 

 have been able to find is in the Memoirs of General William 

 Miller (London, 1828), where on a rough sketch-map he notes 

 that the water of Lake Parinacochas is brackish. 



