264 Gravel-Terraces of Copiapo, paeth. 



stratum was formed of broken shells and sand cemented 

 by white calcareous matter, and abounding with em- 

 bedded recent shells, of which the Mulinia Byronensis 

 and Pecten purpuratus were the most numerous. The 

 lower plain stretches for some miles southward, and for 

 an unknown distance northward, but not far up the 

 valley; its seaward face, according to Meyen, is worn 

 into caves above the level of the present beach. The 

 valley of Copiapo is much less steeply inclined and less 

 direct in its course than any other valley which I saw 

 in Chile : and its bottom does not generally consist of 

 gravel : there are no step-formed terraces in it, except at 

 one spot near the mouth of the great lateral valley of 

 the Despoblado where there are only two. one above the 

 other : lower down the valley, in one place I observed 

 that the solid rock had been cut into the shape of a 

 beach and was smoothed over with shingle. 



Northward of Copiapo, in lat. 26° S., the old voyager 

 Wafer l found immense numbers of sea-shells some 

 miles from the coast. At Cobija (lat. 22° 34'), M. 

 d'Orbigny observed beds of gravel and broken shells, 

 containing ten species of recent shells; he also found, 

 on projecting points of porphyry, at a height of 300 

 feet, shells of Concholepas, Chiton, Calyptrgea, Fissurella, 

 and Patella, still attached to the spots on which they 

 had lived. M. d'Orbigny argues from this fact, that 

 the elevation must have been great and sudden : 2 to 



o 



1 Burnett's ' Collection of Voyages,' vol. iv. p. 193. 



2 ' Voyage. Part. Geolog.' p. 94. fit. d'Orbigny (p. 98" in sum- 

 ming up, says, ' S'il est certain (as he believes) que tous les terrains 

 en pente, compris entre la mer et les montagnes sont l'ancien rivage 

 de la mer, on doit supposer, pour l'ensemble, un exhaussement qui ne 

 serait pas moindre de deux cent metres ; il faudrait supposer encore 

 que ce soulevement n'a point etegraduel; . . . mais qu'il resulterait 

 d'une seule et meme cause fortuite,' &c. Now, on this view, when 

 the sea was forming the beach at the foot of the mountains, many 

 shells of Concholepas, Chiton, Calyptrsea, Fissurella, and Patella 

 (which are known to live close to the beach), were attached to rocks 



