318 USPALLATA PASS. [CHAP. xv. 



often mentioned in Chile, but higher, being six thousand feet 

 above the sea. This range has nearly the same geographical 

 position with respect to the Cordillera, which the gigantic Portillo 

 line has, but it is of a totally different origin : it consists of various 

 kinds of submarine lava, alternating with volcanic sandstones and 

 other remarkable sedimentary deposits ; the whole having a very 

 close resemblance to some of the tertiary beds on the shores of the 

 Pacific. From this resemblance I expected to find silicified wood, 

 which is generally characteristic of those formations. I was 

 gratified in a very extraordinary manner. In the central part of 

 the range, at an elevation of about seven thousand feet, I observed 

 on a bare slope some snow-white projecting columns. These were 

 petrified trees, eleven being silicified, and from thirty to forty con- 

 verted into coarsely-crystallized white calcareous spar. They were 

 abruptly broken off, the upright stumps projecting a few feet above 

 the ground. The trunks measured from three to five feet each in 

 circumference. They stood a little way apart from each other, but 

 the whole formed one group. Mr. Kobert Brown has been kind 

 enough to examine the wood : he says it belongs to the fir tribe, 

 partaking of the character of the Araucariau family, but with some 

 curious points of affinity with the yew. The volcanic sandstone in 

 which the trees were embedded, and from the lower part of which 

 they must have sprung, had accumulated in successive thin layers 

 around their trunks; and the stone yet retained the impression of 

 the bark. 



It required little geological practice to interpret the marvellous 

 story which this scene at once unfolded ; though I confess I was 

 at first so much astonished that I could scarcely believe the plainest 

 evidence. I saw the spot where a cluster of fine trees once waved 

 their branches on the shores of the Atlantic, when that ocean (now 

 driven back 700 miles) came to the foot of the Andes. I saw that 

 they had sprung from a volcanic soil which had been raised above 

 the level of the sea, and that subsequently this dry land, with its 

 upright trees, had been let down into the depths of the ocean. In 

 these depths, the formerly dry land was covered by sedimentary 

 beds, and these again by enormous streams of submarine lava one 

 such mass attaining the thickness of a thousand feet ; and these 

 deluges of molten stone and aqueous deposits five times alternately 

 had been spread out. The ocean which received such thick 

 masses, must have been profoundly deep; but again the subter- 



