ollow, is the
continuation of the bed of the river which is intersected by the chain
of hills. Descending into the valley, and again following the course of
the Rio Seco to the distance of about three leagues, we reach the
village of Alcocoto, and once more arrive on the bank of the Rio de
Chillon.

Here, therefore, we have evidence of the following remarkable facts,
viz.:--that at some former period the river of Chillon flowed
north-westward from Alcocoto to Cavallero, in the bed that is now
dry; and that a chain of hills has been upheaved diagonally across the
valley and the river. By this chain of hills the water, being dammed
up, formed a lake; then it was again driven back; until the stream
broke into a new course at Alcocoto, by which means the lake emptied
itself, and, having no new supply of water, it dried up. Now the Rio
de Chillon flows from Alcocoto to Cavallero, taking a wide turn, first
westward, next south-westward, and lastly, direct south, until, at a
sharp angle, it unites with the old bed of the river. The point of
junction is a quarter of a mile from the Hacienda Cavallero. This is,
however, not a solitary example of the course of a river being
interrupted by the uplifting of a ridge of hills. A similar instance
is mentioned by Mr. Darwin, who, however, did not see it himself, but
who describes it as follows, from the observation of his countryman,
Mr. Gill, the engineer:--

"Travelling from Casma to Huaraz, not far distant from Lima, he (Mr.
Gill) 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 channel, which in one spot was about forty yards
in breadth, and eight 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 forty or
fifty feet perpendicular. We here have unequivocal evidence that a ridge
had been uplifted right across the old bed of the stream