chap. xv. Section up the Valley. 549 



Ostrea, Turritella, and Hippurite indicate the creta- 

 ceous period ; and the Gryphasa appears to Prof. 

 Forbes to be identical with a species, associated in 

 Southern India with unquestionably cretaceous forms. 

 On the other hand, the two Terebratulee and the Spirifer 

 point, in the opinion both of M. d'Orbigny and Prof. 

 Forbes, to the oolitic series. Hence M. d'Orbigny, not 

 having himself examined this country, has concluded 

 that there are here two distinct formations ; but the 

 Spirifer and^ T. asnigma were certainly included in 

 the same bed with the Pecten and Ostrea, whence I 

 extracted them ; and the geologist M. Domeyko sent 

 home the two Terebratulae with the other-named shells, 

 from the same locality, without specifying that they 

 came from different beds. Again, as we shall presently 

 see, in a collection of shells given me from Guasco, the 

 same species, and others presenting analogous differences 

 are mingled together, and are in the same condition; 

 and lastly, in three places in the valley of Copiapo, I 

 found some of these same species similarly grouped. 

 Hence there cannot be any doubt, highly curious 

 though the fact be, that these several fossils, namely, 

 the Hippurites, Gryphaaa, Ostrea, Pecten, Turritella, 

 Nautilus, two Terebratulaa, and Spirifer all belong to 

 the same formation, which would appear to form a 

 passage between the oolitic and cretaceous systems of 

 Europe. Although aware how unusual the term must 

 sound, I shall, for convenience sake, call this formation 

 cretaceo-oolitic. Comparing the sections in this valley 

 of Coquimbo with those in the Cordillera described in 

 the last chapter, and bearing in mind the character of 

 the beds in the intermediate district of Los Hornos, 

 there is certainly a close general mineralogical resem- 

 blance between them, both in the underlying porphy- 

 ritic conglomerate, and in the overlying gypseous 



