382 
NORTHERN CHILE 
CHAP. 
may have been greater. As the peculiarly arid character of the 
climate is evidently a consequence of the height of the 
Cordillera, we may feel almost sure that before the later 
elevations, the atmosphere could not have been so completely 
drained of its moisture as it now is ; and as the rise has been 
gradual, so would have been the change in climate. On this 
notion of a change of climate since the buildings were inhabited, 
the ruins must be of extreme antiquity, but I do not think 
their preservation under the Chilian climate any great difficulty. 
We must also admit on this notion (and this perhaps is a 
greater difficulty) that man has inhabited 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 Indio- 
human period : but such small elevations could have had little 
power in deflecting the moisture-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 1 with Mr. 
Gill, a civil engineer, who had seen much of the interior country. 
He told me that a conjecture of a change of climate had some¬ 
times 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 constructed on so 
wonderful a scale, having been injured by neglect and by 
subterranean movements. I may here mention 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 uniform breadth, but of very 
considerable length. Is it not most wonderful that men should 
1 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. 
