XVI 
ELEVATION OF A RIVER-COURSE 
383 
have attempted such operations, 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 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 watercourse 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 channel, 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 down hill. He 
imagined that the downward slope had a fall of about 40 or 50 
feet perpendicular. We here have unequivocal evidence that 
a ridge had been uplifted right across the old bed of a stream. 
From the moment the river-course was thus arched, the water 
must necessarily have been thrown back, and a new channel 
formed. From that moment, also, the neighbouring plain 
must have lost its fertilising stream and become a desert. 
June 27th .—We set out early in the morning, and by mid¬ 
day reached the ravine of Paypote, where there is a tiny rill of 
water, with a little vegetation, and even a few algarroba trees, a 
kind of mimosa. From having firewood, a smelting-furnace had 
formerly been built here : we found a solitary man in charge of 
it, whose sole employment was hunting guanacos. At night it 
froze sharply ; but having plenty of wood for our fire, we kept 
ourselves warm. 
28th .—We continued gradually ascending, and the valley 
now changed into a ravine. During the day we saw several 
guanacos, and the track of the closely-allied species, the Vicuna : 
this latter animal is pre-eminently alpine in its habits ; it seldom 
descends much below the limit of perpetual snow, and therefore 
haunts even a more lofty and sterile situation than the guanaco. 
