124 



Galapagos Archipelago. 



PAST I. 



the beach, represents the axis of the crater. The 

 streams of lava can be followed up a litttle ravine, at 

 right angles to the coast, for between ten and fifteen 

 yards, where they are hidden by detritus : along the 

 beach they are visible for nearly eighty yards, and I 

 do not believe that they extend much farther. The 

 three lower streams are united to the pinnacle ; and at 

 the point of junction (as is shown in the accompanying 

 rude sketch made on the spot), they are slightly arched, 



No. 14. 



Segment of a very small orifice of eruption, en the beach of Fresh-water Bay. 



as if in the act of flowing over the lip of the crater. 

 The six upper streams no doubt were originally united 

 to this same column before it was worn down by the 

 sea. The lava of these streams is of similar com- 

 position with that of the pinnacle, excepting that the 

 crystals of albite appear to be more comminuted, and 

 the grains of fused augite are absent. Each stream 

 is separated from the one above it by a few inches, or 

 at most by one or two feet in thickness, of loose frag- 

 mentary scoriae, apparently derived from the abrasion 

 of the streams in passing over each other. All these 

 streams are very remarkable from their thinness. I 

 carefully measured several of them ; one was eight inches 

 thick, but was firmly coated with three inches above, 



