. From the
moment the river-course was thus arched the water must necessarily have
been thrown back, and a new channel formed. From that period, also, the
neighboring plain must have lost its fertilizing stream, and become a
desert."[55]

The inference here deduced is, that the rising took place at a period
when the district was inhabited and cultivated by men. Of the period
of the uplifting between Cavallero and Alcocoto I could discern no
proofs. But the impression produced by the dry river bed involuntarily
suggests the idea that, at no very distant period, it must have been
the lodgment of a stream; for it is in all respects similar to the
temporary dry river beds so frequently met with on the coast of Peru.

I made repeated visits to the Rio Seco, and I always contemplated with
wonder the curious deviation of the river's course. But I must candidly
confess that during my abode in Peru, I did not venture to attribute
that deviation to so partial an uplifting; for I was ignorant of the
existence of any similar phenomenon which would have supported such an
opinion. Now, however, the example referred to by the eminent English
geologist, and which has its existence on the same coast of Peru, sets
all my doubts at rest, and I am quite convinced of the correctness of
Mr. Darwin's view of the subject.

Having made this digression, I must now carry the reader back to
Cocachacra. Pursuing the road to the distance of three leagues further,
we arrive at San Geronimo de Surco. The valley in this part becomes more
contracted; but on the whole its character is unchanged, with the
exception that the mountains gradually become higher and steeper, and
the soil less fertile. The road frequently runs along lofty walls of
rock, or winds round sharp projections, which overhang deep chasms, in
passing which the greatest precaution is requisite.

In several of the valleys on the road from the coast to the Sierra, and
above all in the valley of Surco, there are certain springs, the water
of which the Indians never drink. When a stranger unguardedly approaches
one of these springs for the purpose of quenching his thirst, he is
saluted by warning cries of _Es agua de Veruga!_ (It is veruga water!)
Even horses and mules are not suffered to refresh themselves at these
springs, where the water is supposed to have the effect of producing a
disorder called the _Verugas_. As the existence of this disease is not
known in any other country, ther