FOSSIL TREES. 181 



CHILE. 



stone and watery deposits five times alternately had been 

 spread out. The ocean which received such thick masses 

 must have been profoundly deep; but again the subterra- 

 nean forces exerted themselves, and I now beheld the bed 

 of that ocean forming a chain of mountains more than seven 

 thousand feet in height. Nor had those opposing forces been 

 idle which are always at work wearing down the surface of 

 the land: the great piles of strata had been cut through by 

 many wide valleys, and the trees, now changed into silex, 

 were exposed projecting from the volcanic soil (now changed 

 into rock), whence formerly, in a green and budding state, 

 they had raised their lofty heads. Now all is utterly irre- 

 claimable and desert; even the lichen cannot cling to the 

 stony casts of former trees. Vast and scarcely comprehensi- 

 ble as such changes must ever appear, yet they have all oc- 

 curred within a period which is recent when compared with 

 the history of the Cordillera; and the Cordillera itself is ab- 

 solutely modern as compared with many of the fossiliferous 

 strata of Europe and America. 



In the valley of Copiapo, in northern Chile, I stayed two 

 days collecting fossil shells and wood. Great prostrate silici- 

 fied trunks of trees were extraordinarily numerous. I meas- 

 ured one which was fifteen feet in circumference. How sur- 

 prising it is that every atom of the woody matter in this 

 great cylinder should have been removed, and replaced by 

 silex so perfectly that each vessel and pore is preserved! 

 These trees all belonged to the fir-tribe. It was amusing to 

 hear the inhabitants discussing the nature of the fossil shells 

 which I collected, almost in the same terms as were used a 



