chap. ix. Elevation of Conception* 237 



It appears from the researches of Capt. FitzKoy that 

 both the island of St. Mary and Concepcion (which was 

 uplifted only four or five feet) in the course of some 

 weeks subsided, and lost part of their first elevation. 

 I will only add as a lesson of caution, that round the 

 sandy shores of the great Bay of Concepcion, it was 

 most difficult, owing to the obliterating effects of the 

 great accompanying wave, to recognise any distinct 

 evidence of this considerable upheaval; one spot must 

 be excepted, where there was a detached rock which 

 before the earthquake had always been covered by the 

 sea, but afterwards was left uncovered. 



On the island of Quinquina (in the Bay of Concep- 

 cion), I found, at an estimated height of 400 feet, 

 extensive layers of shells, mostly comminuted, but some 

 perfectly preserved and closely packed in black vege- 

 table mould ; they consisted of Concholepas, Fissurella, 

 Mytilus, Trochus, and Balanus. Some of these layers 

 of shells rested on a thick bed of bright-red, dry, friable 

 earth, capping the surface of the tertiary sandstone, 

 and extending, as I observed whilst sailing along the 

 coast, for 150 miles southward : at Valparaiso, we shall 

 presently see that a similar red earthy mass, though 

 quite like terrestrial mould, is really in chief part of 

 recent marine origin. On the flanks of this island of 

 Quiriquina, at a less height than the 400 feet, there 

 were spaces several feet square, thickly strewed with 

 fragments of similar shells. During a subsequent visit 

 of the Beagle to Concepcion, Mr. Kent, the assistant- 

 surgeon, was so kind as to make for me some measure- 

 ments with the barometer : he found many marine 

 remains along the shores of the whole bay, at a height 

 of about twenty feet ; and from the hill of Sentinella 

 behind Talcahuano, at the height of 160 feet, he col- 

 lected numerous shells, packed together close beneath 



