chap. ix. Gravel-Terraces of Coquimbo. 253 



The bottom plain (A) is about a mile in width, and 

 rises quite insensibly from the beach to a height of 

 twenty-five feet at the foot of the next plain : it is sandy, 

 and abundantly strewed with shells. 



Plain or terrace (B) is of small extent, and is almost 

 concealed by the houses of the town, as is likewise the 

 escarpment of terrace (0). On both sides of a ravine, 

 two miles south of the town, there are two little ter- 

 races, one above the other, evidently corresponding with 

 (B) and (C) ; and on them marine remains of the species 

 already enumerated were plentiful. Terrace (E) is very 

 narrow, but quite distinct and level ; a little southward 

 of the town there were traces of a terrace (D) inter- 

 mediate between (E) and (C). Terrace (F) is part of 

 the fringe-like plain, which stretches for the eleven 

 miles along the coast ; it is here composed of shingle, 

 and is 100 feet higher than where composed of calca- 

 reous matter. This greater height is obviously due to 

 the quantity of shingle, which at some former period 

 has been brought down the great valley of Coquimbo. 



Considering the many shells strewed over the ter- 

 races (A) (B) and (0), and a few miles southward on 

 the calcareous plain, which is continuously united with 

 the upper step-like plain (F), there cannot, I apprehend, 

 be any doubt, that these six terraces have been formed 

 by the action of the sea ; and that their five escarp- 

 ments mark so many periods of comparative rest in the 

 elevatory movement, during which the sea wore into 

 the land. The elevation between these periods may 

 have been sudden and on an average not more than 

 seventy-two feet each time, or it may have been gradual 

 and insensibly slow. From the shells on the three 

 lower terraces, and on the upper one, and I may add on 

 the three gravel-capped terraces at Conch alee, being ail 

 littoral and sub-littoral species, and from the analogical 



