THE VOYAGE OF THE BEAGLE 379 



South America for an immensely long period, inasmuch as 

 any change of climate effected by the elevation of the land 

 must have been extremely gradual. At Valparaiso, within 

 the last 220 years, the rise has been somewhat less than 19 

 feet : at Lima a sea-beach has certainly been upheaved from 

 80 to 90 feet, within the Indo-human period: but such small 

 elevations could have had little power in deflecting the mois- 

 ture-bringing atmospheric currents. Dr. Lund, however, 

 found human skeletons in the caves of Brazil, the appearance 

 of which induced him to believe that the Indian race has 

 existed during a vast lapse of time in South America. 



When at Lima, I conversed on these subjects* with Mr. 

 Gill, a civil engineer, who had seen much of the interior 

 country. He told me that a conjecture of a change of cli- 

 mate had sometimes crossed his mind; but that he thought 

 that the greater portion of land, now incapable of cultivation, 

 but covered with Indian ruins, had been reduced to this state 

 by the water-conduits, which the Indians formerly con- 

 structed on so wonderful a scale, having been injured by 

 neglect and by subterranean movements. I may here men- 

 tion, that the Peruvians actually carried their irrigating 

 streams in tunnels through hills of solid rock. Mr. Gill told 

 me, he had been employed professionally to examine one: 

 he found the passage low, narrow, crooked, and not of uni- 

 form breadth, but of very considerable length. Is it not 

 most wonderful that men should have attempted such opera- 

 tions, without the use of iron or gunpowder ? Mr. Gill also 

 mentioned to me a most interesting, and, as far as I am 

 aware, quite unparalleled case, of a subterranean disturbance 

 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 culti- 

 vation, but now quite barren. Near it was the dry course of 

 a considerable river, whence the water for irrigation had for- 

 merly been conducted. There was nothing in the appearance 

 of the water-course to indicate that the river had not flowed 



s Temple, in his travels through Upper Peru, or Bolivia, in going from 

 Potosi to Oruro, says, " I saw many Indian villages or dwellings in ruins, 

 up even to the very tops of the mountains, attesting a former population 

 where now all is desolate." He makes similar remarks in another place; 

 but I cannot tell whether this desolation has been caused by a want of 

 population, or by an altered condition of the land. 



