Elevation of the Coast of Chili. 101 



Beagle, commanded by Capt. Fitzroy, R.N.," by Charles Darwin, 

 Esq., F.G.S., was afterwards read. 



The subject of recent elevations on the coast of Chili being, in the 

 opinion of many, still open to discussion, Mr. Darwin gives, in this 

 memoir, the results of his own observations. The portion of the coast, 

 more particularly examined by the author, extends from the river 

 Rapel, about sixty miles south of Valparaiso, to Conchali, about 

 eighty miles north of it. 



Close to the mouth of the Rapel, dead barnacles occur adhering to 

 rocks three or four feet above the highest tidal level j and in the 

 neighbouring country recent marine shells are scattered abundantly 

 to the height of about 100 feet. Ten miles to the north, and at an 

 equal distance from the sea, is the village of Bucalemu, in the neigh- 

 bourhood of which are very extensive beds of recent shells. At the 

 bottom of the great valley of Maypo, and some miles from the coast, 

 marine shells of existing species are also numerous j and at St. An- 

 tonio, near the northern point of that river, are large quarries of 

 shells. Between this point and Valparaiso in the ravine Quebrada 

 Onda, the remains of a species of shell common on the coast, were 

 noticed by the author. Along the bold granitic coast south of the pro- 

 montory which forms the bay of Valparaiso, are numerous level and 

 horizontal beds of shells, constituting an almost continuous band, 

 elevated from 60 to 230 feet above the level of the sea. The shells 

 are brittle, but of various kinds, and are all similar and in similar pro- 

 portional numbers to those on the beach. They are mingled with 

 some earth, though packed closely together, and overlie a partially 

 consolidated breccia of granitic fragments which rests on the solid 

 rock. After a careful examination of these deposits, first by himself, 

 and afterwards with Mr. Alison, guarded by a recent inspection of 

 the heaps of shells accumulated by the natives in Tierra del Fuego, 

 Mr. Darwin was convinced that the shelly beds near Valparaiso were 

 formed when the sea occupied a different level. The following are 

 the principal circumstances which lead to this conviction. The great 

 number of the shells forming extensive horizontal beds, whereas the 

 heaps in Tierra del Fuego collected by the inhabitants, always retain a 

 conical figure: their position, at the extremities of headlands inac- 

 cessible from the sea, and unfit for strongholds, being without fresh 

 water: the large proportional number of extremely small shells : and 

 lastly, their brittle and decayed condition, the state of decomposition 

 having an evident relation to the comparative heights at which the 

 shells were lying. Comminuted shells were noticed by Mr. Darwin at 

 the heights of 560 and 1300 feet, but the evidence of^ their having 

 been part of a beach was not convincing. 



At San Lorenzo in the bay of Callao, Mr. Darwin traced a similar 

 process of decay from perfect shells in the lowest beds to a mere 

 layer of calcareous powder in the highest. This phenomenon, he adds, 

 can be observed only in countries where rain never falls. 



On the north side of the bay of Valparaiso, near the Vina del Mar, 

 is an abundance of elevated shells. Mr. Alison, by climbing a point 



