was not yet ready to accept
so bold an idea and he swept it aside.

The people of this wild neighborhood interested Darwin very greatly,
and he describes them with care. In this connection a charming trait
of Darwin's character comes beautifully in evidence. The absolute
purity of his mind, his utter freedom from grossness, shows clearly in
his account of the first really semi-civilized people he had ever
seen.

A little later, while exploring Patagonia, Darwin noticed the
terrace-like formation of that desolate country. A flat near the sea
was succeeded by a rapid rise, then came another flat. Three of these
terraces in succession stretch back toward the Andes. At the base of
the high terraces Darwin found marine shells, largely similar to those
of the ocean beach so many miles to the east. His study of Lyell led
him to suspect at once that this portion of South America had been
raised in successive stages out of the bed of the Pacific. When they
passed around Cape Horn and up the western coast he hunted for
similar beach marks on the sheer western face of the Andes, and found
them without difficulty, confirming his idea of the recent rise of
this end of the Andean chain.

The _Beagle_ continued its voyage up the western coast of South
America until it reached Peru. Once more the abundance of tropical
life is under Darwin's eyes, but now it is the life of an entirely
different section. The dry climate of Peru furnished him with an
environment distinctly unlike that of the moist Brazilian forest. He
collects now with avidity, gathering especially insects and birds.
Then the ship turned its prow westward across the Pacific, only to
stop five hundred miles out at the Galapagos Islands. This little
group he studied intensely, collecting large numbers of insects and
birds. He had not worked over his collection long before he realized
that each island in the group had peculiarities which marked its
animals from those of any other island. Whenever two islands were
close together in the group the differences in their fauna were found
to be comparatively slight. If, however, he examined the animals from
two islands lying at opposite ends of the group, the differences were
always considerably greater. There was, however, a strong general
resemblance among them all and a distant though not so strong
resemblance to the corresponding animals of the Peruvian coast. On
leaving the Galapagos group, Charles Darwin writes in his di