546 Coquimbo, paet it. 



any farther up the valley, and this point is about two- 

 thirds of the distance between the Pacific and the 

 main Cordillera. 



I will describe only one other section, namely, on 

 the north side of the R. Claro, which is interesting 

 from containing fossils : the strata are much dislocated 

 by faults and dikes, and are inclined to the north, 

 towards a mountain of andesite and porphyry, into 

 which they appear to become almost blended. As the 

 beds approach this mountain, their inclination increases 

 up to an angle of 70°, and in the upper part, the rocks 

 become highly metamorphosed. The lowest bed visible 

 in this section, is a purplish hard sandstone. Secondly, 

 a bed 200 or 300 feet thick, of a white siliceous sand- 

 stone, with a calcareous cement, containing seams of 

 slaty sandstone, and of hard yellowish-brown (dolomitic ?) 

 limestone; numerous, well-rounded, little pebbles of 

 quartz are included in the sandstone. Thirdly, a dark 

 coloured limestone with some quartz pebbles, from fifty 

 to sixty feet in thickness, containing numerous silicified 

 shells, presently to be enumerated. Fourthly, very 

 compact, calcareous, jaspery sandstone, passing into 

 (fifthly) a great bed, several hundred feet thick, of 

 conglomerate, composed of pebbles of white, red, and 

 purple porphyries, of sandstone and quartz, cemented 

 by calcareous matter. I observed that some of the 

 finer parts of this conglomerate were much indurated 

 within a foot of a dike eight feet in width, and were 

 rendered of a paler colour with the calcareous matter 

 segregated into white crystallised particles ; some parts 

 were stained green from the colouring matter of the 

 dike. Sixthly, a thick mass, obscurely stratified, of a 

 red sedimentary stone or sandstone, full of crystalline 

 calcareous matter, imperfect crystals of oxide of iron, 

 and I "believe of feldspar, and therefore closely resem- 



