62 



from one of these floating hills. The action of the waves has 

 produced little or no effect upon (he Basalt along this coast, as 

 its angles retain all the acnteness of a recent fracture, but when 

 the conglomerate predominates, the mass is generally rounded. 



The ocean about these shores is generally of great depth, the 

 materials which constitute its bottom are finely comminuted par- 

 ticles having their origin from the decomposition of the neigh- 

 bouring rocks. Our stay at these islands occupied a period of four 

 weeks, during which time we observed but one ebb and flow of the 

 tide in twenty-four hours. I know not if this be universal, but 

 have been informed by mariners familiar in these seas, that they 

 have generally found it so ; if it should prove to be the case, it is 



decks, and during the time we spent between the latitudes of 60 and 

 70° south, and 54 & 101 west longitude, which was more than two 

 months, we found the current setting with considerable velocity 

 from fl)e south-west to the north-east. The prevailing winds were 

 also westerly, most commonly from the south-west and north-west. 

 The colour of the basalt is generally of a greenish black. The 



length in an upright position above the subjacent conglomerate is 

 about eighty feet. Their external surfaces are closely applied to 

 each other, though but slightly united, consequently they are 

 continually ftilling out by the expansive power of the congealing 

 water among its fissures. When they are exposed to the influ- 

 ence of the atmosphere for any length of time, they are for a small 

 depth of a rusty brown colour, owing no doubt to the iron which 

 they contain becoming partially oxydized : sometimes they are cov- 

 ered by a thin coating of quartz and chalcedony. 



their side in such a manner as to exhibit the surfaces of their base 

 distuictly, which is rough and vesicular. When this is the case 

 they are generally bent, forming quite an arch with the horizon. 

 When they approach the conglomerate for ten or twelve feet, they 

 lose their columnar structure and assume the appearance of a 

 dark coloured flinty slate, breaking readily into irregular rhombic 

 fragments : this fine variety in descending, gradually changes to 

 a greenish colour and a much coarser structure, until it passes 

 mtoamost perfect amygdaloid, the cavities being chiefly filled 



