Narrative of the surveying voyages of his majesty's ships Adventure and Beagle (vol.3)

March 1835. volcanic phenomena. 379 turbance would be situated at that distance in the offing, where the fluid which was most agitated, from overlying the shallow bottom near the land, joined on to that part which covered the depths (but slightly moved) of the ocean. In all distant parts of the coast the small oscillations of the sea, both at the moment of the great shock, and during the lesser following ones, would be confounded with the un- dulation propagated from the focus of disturbance, and hence the series of movements would be undistinguishable. The most remarkable effect (or perhaps speaking more cor- rectly, cause) of this earthquake was the permanent elevation of the land. Captain FitzRoy having twice visited the island of Santa Maria, for the purpose of examining every circum- stance with extreme accuracy, has brought a mass of evi- dence in proof of such elevation, far more conclusive than that on which geologists on most other occasions place im- plicit faith. The phenomenon possesses an uncommon degree of interest, from this particular part of the coast of Chile having previously been the theatre of several earth- quakes of the worst class. It is almost certain, from the altered soundings, together with the circumstance of the bottom of the bay near Penco, consisting of hard stone, that there has been an uplifting to the amount of four fathoms, since the famous convulsion of 1751. With this additional instance fresh before us, we may assume as probable, accord- ing to the principles laid down by Mr. LyeU,* other small suc- cessive elevations, and may fearlessly maintain that the prO' blem of the raised shells,t recorded by Ulloa, is explained. Some of the consequences which may be deduced from the phenomena connected with this earthquake are most import- ant in a geological point of view ; but in the present work I cannot do more than simply allude to the results. Although it is known that earthquakes have been felt over enormous * Lyell's Geology, book ii., chap. xvi. t I saw these shells in very great quantities on the flanks of the island of Quinquina.