250 Elevation of Coquimbo. paet ii. 



escarpment of the plain, the included shells appeared to 

 be in exactly the same proportional numbers with those 

 on the beach. On one side of a steep-sided ravine, 

 cutting through the plain behind Herradura Bay, I 

 observed a narrow strip of stratified sand, containing 

 similar shells in similar proportional numbers : a section 

 of the ravine is represented in the following diagram, 

 which serves also to show the general composition of the 

 plain. I mention this case of the ravine chiefly because 

 without the evidence of the marine shells in the sand, 

 any one would have supposed that it had been hollowed 

 out by simple alluvial action. 



No. 22. 



Section of Plain of Coquimbo. 

 B Surface of plain 252 feet above sea. r 



C ■ - 



D I; = „ s — „ 



E- --°'o\o °..'o ,J -C> n- • ~ * O c - ==^— 



LA. 



,*-. 1 1 1 '1 — 1 1 1 — 1 1 







'= - :r--,oo-.| 



Level of sea. 



A. Stratified sand, with, recent shells in same proporcionsas on the beach, half filling 



up a ravine. 



B. Surface of plain with scattered shells in nearly same proportions as on the beach. 

 C Upper calcareous bed, .) with recent shells, but not in same propor- 



D. Lower calcareous sandy bed (Losa), J tions as on the beach. 



E. Upper fernzgino-sandy old tertiary stratum. ) with all, or nearly all, extinct 



F. Lower old tertiary stratum, J shells. 



The escarpment of the fringe-like plain, which 

 stretches for eleven miles along the coast, is in some 

 parts fronted by two or three narrow, step-formed ter- 

 races, one of which at Herradura Bay expands into a 

 small plain. Its surface was there formed of gravel, 

 cemented together bv calcareous matter : and out of it 

 I extracted the following recent shells, which are in 

 a more perfect condition than those from the upper 

 plain : — 



