chap xv. Movements of South America. 60 1 



intersect no formation older than the Patagonian 

 deposits ; so equable has been the upheaval of the beds, 

 that throughout this long line, not a fault in the strati- 

 fication or abrupt dislocation was anywhere observable. 

 Looking to the basal, metamorphic, and plutonic rocks 

 of the continent, the areas formed of them are likewise 

 vast ; and their planes of cleavage and foliation strike 

 over surprisingly great spaces in uniform directions. 

 The Cordillera, with its pinnacles here and there rising 

 upwards of 20,000 feet above the level of the sea, 

 ranges in an unbroken line from Tierra del Fuego, 

 apparently to the Arctic circle. This grand range has 

 suffered both the most violent dislocations, and slow, 

 though grand, upward, aud downward movements in 

 mass : I know not whether the spectacle of its immense 

 valleys, with mountain-masses of once-liquefied and 

 intrusive rocks now bared and intersected, or whether 

 the view of those plains, composed of shingle and sedi- 

 ment hence derived, which stretch to the borders of the 

 Atlantic Ocean, is best adapted to excite our astonish- 

 ment at the amount of wear and tear which these 

 mountains have undergone. 



The Cordillera from Tierra del Fuego to Mexico, is 

 penetrated by volcanic orifices, and those now in action 

 are connected in great trains. The intimate relation 

 between their recent eruptions and the slow elevation 

 of the continent in mass, 1 appears to me highly impor- 

 tant, for no explanation of the one phenomenon can be 

 considered as satisfactory which is not applicable to 

 the other. The permanence of the volcanic action on 

 this chain of mountains is, also, a striking fact ; first, 

 we have the deluges of submarine lavas alternating 

 with the porphyritic cod glomerate strata, then occa- 



1 On the connection of certain Volcanic Phenomena in South 

 America. * Gedog. Transact.,' vol. v. p. 609. 



