394 PERU CHAP. 



exactly similar appearance, and lying in the same relative 

 position. I have no doubt that this upper layer originally 

 existed as a bed of shells, like that on the eighty -five -feet 

 ledge ; but it does not now contain even a trace of organic 

 structure. The powder has been analysed for me by Mr. T. 

 Reeks ; it consists of sulphates and muriates both of lime and 

 soda, with very little carbonate of lime. It is known that 

 common salt and carbonate of lime left in a mass for some 

 time together partly decompose each other ; though this does 

 not happen with small quantities in solution. As the half- 

 decomposed shells in the lower parts are associated with much 

 common salt, together with some of the saline substances com- 

 posing the upper saline layer, and as these shells are corroded 

 and decayed in a remarkable manner, I strongly suspect that 

 this double decomposition has here taken place. The 

 resultant salts, however, ought to be carbonate of soda and 

 muriate of lime ; the latter is present, but not the carbonate of 

 soda. Hence I am led to imagine that by some unexplained 

 means the carbonate of soda becomes changed into the 

 sulphate. It is obvious that the saline layer could not have 

 been preserved in any country in which abundant rain 

 occasionally fell ; on the other hand, this very circumstance, 

 which at first sight appears so highly favourable to the long 

 preservation of exposed shells, has probably been the indirect 

 means, through the common salt not having been washed 

 away, of their decomposition and early decay. 



^ I was much interested by finding on the terrace, at the 

 height of eighty-five feet, cvibedded amidst the shells and much 

 sea-drifted rubbish, some bits of cotton thread, plaited rush, 

 and the head of a stalk of Indian corn : I compared these 

 relics with similar ones taken out of the Huacas, or old 

 Peruvian tombs, and found them identical in appearance. On 

 the mainland in front of San Lorenzo, near Bellavista, there is 

 an extensive and level plain about a hundred feet high, of 

 which the lower part is formed of alternating layers of sand 

 and impure clay, together with some gravel, and the surface, to 

 the depth of from three to six feet, of a reddish loam, contain- 

 ing a few scattered sea-shells and numerous small fragments of 

 coarse red earthenware, more abundant at certain spots than at 

 others. At first I was inclined to believe that this superficial 



