1835.] ELEVATION OF A RIVER-COURSE. 359 
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 cultivation, but now 
quite barren. Near it was the dry course of a considerable 
river, whence the water for irrigation had formerly been con- 
ducted. 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 
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 incli- 
nation: Mr. Gill, therefore, was much astonished, when walk- 
ing 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 un- 
equivocal 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 fertilizing 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 fire-wood, a smelting-furnace had for- 
merly 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 Vicuiia: this latter 
eanimal is pre-eminently alpine in its habits; it seldom descends 
