130 Galapagos Archipelago, part i. 



Elevation of the land. — Proofs of the rising of the 

 land are scanty and imperfect. At Chatham Island, I 

 noticed some great blocks of lava, cemented by cal- 

 careous matter, containing recent shells ; but they 

 occurred at the height of only a few feet above high- 

 water mark. One of the officers gave me some frag- 

 ments of shells, which he found embedded several 

 hundred feet above the sea, in the tuff of two craters, 

 distant- from each other. It is possible, that these 

 fragments may have been carried up to their present 

 height in an eruption of mud ; but as, in one instance, 

 they were associated with broken oyster-shells, almost 

 forming a layer, it is more probable that the tuff was 

 uplifted with the shells in mass. The specimens are 

 so imperfect that they can be recognised only as be- 

 longing to recent marine genera. On Charles Island, 

 I observed a line of great rounded blocks, piled on the 

 summit of a vertical cliff, at the height of fifteen feet 

 above the line, where the sea now acts during the 

 heaviest gales. This appeared, at first, good evidence 

 in favour of the elevation of the land ; but it was 

 quite deceptive, for I afterwards saw on an adjoining 

 part of this same coast, and heard from eye-witnesses, 

 that wherever a recent stream of lava forms a smooth 

 inclined plane, entering the sea, the waves during gales 

 have the power of rolling up rounded blocks to a great 

 height, above the line of their ordinary action. As the 

 little cliff in the foregoing case is formed by a stream 

 of lava, which, before being worn back, must have en- 

 tered the sea with a gently sloping surface, it is possible 

 or rather it is probable, that the rounded boulders, 

 now lying on its summit, are merely the remnant of 

 those which had been rolled up during storms to their 

 present height. 



Direction of the fissures of eruption. — The volcanic 



