2 48 Elevation of Coquimbo. part n. 



Limari, out of which hills abruptly rise like islets, and 

 other hills project like headlands on a coast. The 

 surface of the fringe-like plain appears level, but differs 

 insensibly in height, and greatly in composition, in 

 different parts. 



At the mouth of the valley of Coquimbo, the surface 

 consists wholly of gravel, and stands from 800 to 350 

 feet above the level of the sea, being about 100 feet 

 higher than in other parts. In these other and lower 

 parts, the superficial beds consist of calcareous matter, 

 and rest on ancient tertiary deposits hereafter to be 

 described. The uppermost calcareous layer is cream- 

 coloured, compact, smooth-fractured, sub-stalactiform, 

 and contains some sand, earthy matter, and recent shells. 

 It lies on, and sends wedge-like veins into, 1 a much 

 more friable, calcareous, tuff-like variety; and both 

 rest on a mass about twenty feet in thickness, formed 

 of fragments of recent shells, with a few whole ones, 

 and with small pebbles firmly cemented together. This 

 latter rock is called by the inhabitants losa, and is used 

 for building ; in many parts it is divided into strata, 

 which dip at an angle of ten degrees seaward, and ap- 

 pear as if they had originally been heaped in successive 

 layers (as may be seen on coral-reefs) on a steep beach. 

 This stone is remarkable from being in parts entirely 

 formed of empty, pellucid capsules or cells of calcareous 

 matter, of the size of small seeds : a series of specimens 

 unequivocally showed that all these capsules once con- 

 tained minute rounded fragments of shells which have 



1 In many respects this upper hard, and the underlying more 

 friable varieties, resemble the great superficial beds at King George's 

 Sound in Australia, which I have described in Chapter VII. p. 161. 

 There could be little doubt that the upper layers there have been 

 hardened by the action of rain on the friable calcareous matter, and 

 that the whole mass has originated in the decay of minutely commi- 

 nuted sea-shells and corals. 



