vni EIVERS AND LAKES 289 



over, is perhaps the more interesting as being 

 evidently very recent. 



"Mr. GUI," he says, "mentioned to me a 

 most interesting, and as far as I am aware, 

 quite unparalleled case, of a subterranean dis- 

 turbance having changed the drainage of a 

 country. Travelling from Casma to Huaraz 

 (not very far distant from Lima) he found a 

 plain covered with ruins and marks of ancient 

 cultivation, but now quite barren. Near it 

 was the dry course of a, considerable river, 

 whence the water for irrigation had formerly 

 been conducted. There was nothing in the 

 appearance of the water-course to indicate 

 that the river had not flowed there a few 

 years previously ; in some parts beds of sand 

 and gravel were spread out ; in others, the 

 solid rock had been worn into a broad chan- 

 nel, which in one spot was about 40 yards in 

 breadth and 8 feet deep. It is self-evident 

 that a person following up the course of a 

 stream will always ascend at a greater or less 

 inclination. Mr. Gill therefore, was much 

 astonished when walking up the bed of this 

 ancient river, to find himself suddenly going 



