chap. xv. Iquique, Peru. 579 



red sandstone, sometimes so highly calcareous as to 

 have a crystalline fracture, — argillaceous limestone, — 

 black calcareous slate-rock, like that so often described 

 at Copiapo and other places, — thinly laminated, fine- 

 grained, greenish, indurated, sedimentary, fusible rocks, 

 approaching in character to the so-called pseudo-hone- 

 stone of Chile, including thin contemporaneous veins of 

 gypsum, — and lastly, much calcareous, laminated por- 

 celain jasper, of a green colour, with red spots, and of 

 extremely easy fusibility : I noticed one conformable 

 stratum of a freckled-brown, feldspathic lava. I may 

 here mention that I heard of great beds of gypsum in 

 the Cordillera. The only novel point in this formation, is 

 the presence of innumerable thin layers of rock-salt, 

 alternating with the laminated and hard, but sometimes 

 earthy, yellowish, or bright red and ferruginous sand- 

 stones. The thickest layer of salt was only two inches, 

 and it thinned out at both ends. On one of these 

 saliferous masses I noticed a stratum about twelve feet 

 thick, of dark-brown, hard brecciated, easily fusible 

 rock, containing grains of quartz and of black oxide of 

 iron, together with numerous imperfect fragments of 

 shells. The problem of the origin of salt is so obscure, 

 that every fact, even geographical position, is worth 

 recording. 1 With the exception of these saliferous 



1 It is well known that stratified salt is found in several places on 

 the shores of Peru. The island of San Lorenzo, off Lima, is composed 

 of a pile of thin strata, about 800 feet in thickness, composed of 

 yellowish and purplish, hard siliceous, or earthy sandstones, alter- 

 nating with thin layers of shale, which in places passes into a 

 greenish, semi-porcellanic, fusible rock. There are some thin beds of 

 reddish muclstone, and soft ferruginous rotten-stones, with layers of 

 gypsum. In nearly all these varieties, especially in the softer sand- 

 stones, there are numerous thin seams of rock-salt : I was informed 

 that one layer has been found two inches in thickness. The manner 

 in which the minutest fissures of the dislocated beds have been 

 penetrated by the salt, apparently by subsequent infiltration, is very 

 curious. On the south side of the island, layers of coal and of 

 impure limestone have been discovered. Hence we here have salt, 



