to the organic world. Even in the face of his own evidence against it, he clung to
the idea of a Creationist God who would have to be constantly restocking the world
with new species, different from but similar to those which had just been destroyed
by some geological catastrophe. His doctrine of small accumulative changes soon
became the underlying principle of Darwin’s geological studies: ‘It altered the whole
tone of one’s mind, and therefore ... when seeing a thing never seen by Lyell, one yet
saw it partially through his eyes’. Inspired by Charles Lyell, the young Darwin began
his geological studies at Porto Praya in the Cape Verde Islands and you can sense his
excitement in describing this geological outcrop:
The geology of this island is the most interesting part of its natural history. On entering
the harbour, a perfectly horizontal white band, in the face of the sea cliff, may be seen
running for some miles along the coast, and at the height of about forty-five feet above the
water. Upon examination, this white stratum is found to consist of calcareous matter with
numerous shells embedded, most or all of which now exist on the neighbouring coast. It
rests on ancient volcanic rocks and has been covered by a stream of basalt, which must have
entered the sea when the white shelly bed was lying at the bottom.Here was geology in action. The basalt had flowed out from an associated volcano
to cover the shell beds on the sea floor, the island had then been slowly pushed up by
subterranean forces and the irregularities in the white band indicated these forces were
still in action. Fifty years later Darwin still remembered the impact of this day and
when it first dawned on him that he might write a book on the geology of the various
countries he was going to visit and how this idea made him thrill with delight. At the
end of February the Beagle reached the coast of South America at San Salvador in
Brazil. Here Darwin was able to explore a tropical forest for the first time, another day
that he will obviously never forget:
The day has passed delightfully. Delight itself, however, is a weak term to express the
feelings of a naturalist who, for the first time, has wandered by himself in a Brazilian forest
... The elegance of the grasses, the novelty of the parasitical plants, the beauty of the flowers,
the glossy green of the foliage, but above all the general luxuriance of the vegetation, filled
me with admiration. A most paradoxical mixture of sound and silence pervades the shady
parts of the wood. The noise from the insects is so loud that it may be heard even in a
vessel anchored several hundred yards from the shore; yet within the recesses of the forest
a universal silence appears to reign. To a person fond of natural history, such a day as this
brings with it a deeper pleasure than he can ever hope to experience.(^68) Where Australia Collides with Asia
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