chap. x. Basin- like Plains of Chile. 287 



important ; because, as we shall presently show, they 

 send arms or fringes far up the main valleys of the 

 Cordillera. Many of the inhabitants believe that these 

 plains were once occupied by lakes, suddenly drained ; 

 but I conceive that the number of the separate breaches 

 at nearly the same level in the mountains surrounding 

 them, quite precludes this idea. Had not such distin- 

 guished naturalists as MM. Meyen and Gay stated 

 their belief that these deposits were left by great 

 debacles rushing down from the Cordillera, I should 

 not have noticed a view, which appears to me from 

 many reasons improbable in the highest degree — 

 namely, from the vast accumulation of w > ell-rounded 

 joebbles — their frequent stratification with layers of 

 sand — the overlying beds of calcareous tuff — this same 

 substance coating and uniting the fragments of rock 

 on the hummocks in the plain of Santiago — and lastly 

 even from the worn, rounded, and much denuded state 

 of these hummocks, and of the headlands which pro- 

 ject from the surrounding mountains. On the other 

 hand, these several circumstances, as well as the con- 

 tinuous union of the basins at the foot of the Cor- 

 dillera, with the great plain of the Rio Rapel which 

 still retains the marks of sea-action at various levels, 

 and their general similarity in form and composition 

 with the many plains near the coast, which are either 

 similarly marked or are strewed with upraised marine 

 remains, fully convince me that the mountains bound- 

 ing these basin-plains were breached, their islet-like 

 projecting rocks worn, and the loose stratified detritus 

 forming their now level surfaces deposited, by the sea, 

 as the land slowly emerged. It is hardly possible to 

 state too strongly the perfect resemblance in outline be- 

 tween these basin-like, long, and narrow plains of Chile, 

 (especially when in the early morning the mists hang- 



