1835.] THE ELEVATORY AND ERUPTIVE SOURCES. 22$ 



waters has been a retirement. Some authors have attempted to explain 

 this, by supposing that the water retains its level, whilst the land 

 oscillates upwards ; but surely the water dose to' the land, eren OOA 

 rather steep coast, would partake of the motion of the bottom : more- 

 over, as urged by Mr. Lyell, similar movements of the sea have 

 occurred at islands far distant from the chief line of disturbance, as was 

 the case with Juan Fernandez during this earthquake, and with Madeira 

 during the famous Lisbon shock. I suspect (but the subject is a very 

 obscure one) that a wave, however produced, first draws the water 

 from the shore on which it is advancing to break: I have observed 

 that this happens with the little waves from the paddles of a steam- 

 boat. It is remarkable that whilst Talcahuano and Callao (near Lima), 

 both situated at the head of large shallow bays, have suffered during 

 every severe earthquake from great waves, Valparaiso, seated close to 

 the edge of profoundly deep water, has never been overwhelmed, 

 though so often shaken by the severest shocks. From the great wave 

 not immediately following the earthquake, but sometimes after the 

 interval of even half an hour, and from distant islands being affected 

 similarly with the coasts near the focus of the disturbance, it appears 

 that the wave first rises in the offing ; and as this is of general occur- 

 rence, the cause must be general : I suspect we must look to the line, 

 where the less disturbed waters of the deep ocean join the water 

 nearer the coast, which has partaken of the movements of the land, as 

 the place where the great wave is first generated ; it would also appear 

 that the wave is larger or smaller, according to the extent of shoal 

 water which has been agitated together with the bottom on which it 

 rested. 



The most remarkable effect of this earthquake was the permanent 

 elevation of the land ; it would probably be far more correct to speak of 

 it as the cause. There can be no doubt that the land round the Bay of 

 Concepcion was upraised two or three feet ; but it deserves notice, that 

 owing to the wave having obliterated the old lines of tidal action on the 

 sloping sandy shores, I could discover no evidence of this fact, except in 

 the united testimony of the inhabitants, that one little rocky shoal, now 

 exposed, was formerly covered with water. At the island of S. Maria 

 (about thirty miles distant) the elevation was greater; on one part, 

 Captain Fitz Roy found beds of putrid mussel-shells still adhering 

 to the rocks, ten feet above high-water mark : the inhabitants had 

 formerly dived at low-water spring-tides for these shells. The elevation 

 of this province is particularly interesting, from its having been the 

 theatre of several other violent earthquakes, and from the vast numbers 

 of sea-shells scattered over the land, up to a height of certainly 600, 

 and I believe, of i,ooofeet. At Valparaiso, as I have remarked, similar 

 shells are found at the height of 1,300 feet: it is hardly possible to 

 doubt that this great elevation has been effected by successive small 

 uprisings, such as that which accompanied or caused the earthquake 

 01 this year, and likewise by an insensibly slow rise, which is certainly 

 in progress on some parts of this coast. 



