Journal of Researches into the Natural History and Geology of the Countries Visited During the Voyage Round the World of H.M.S. Beagle Under · Charles Darwin
CHAPTER XX
Keeling Island — Singular appearance — Scanty Flora — Transport of seeds — Birds and insects — Ebbing and flowing springs — Fields of dead coral — Stones transported in the roots of trees — Great crab — Stinging corals — Coral-eating fish — Coral formations — Lagoon islands or atolls — Depth at which reef-building corals can live — Vast areas interspersed with low coral islands — Subsidence of their foundations — Barrier-reefs — Fringing-reefs — Conversion of fringing-reefs into barrier-reefs, and into atolls — Evidence of changes in level — Breaches in barrier-reefs — Maldiva atolls, their peculiar structure — Dead and submerged reefs — Areas of subsidence and elevation — Distribution of volcanoes — Subsidence slow and vast in amount. Mauritius, beautiful appearance of — Great crateriform ring of mountains — Hindoos — St. Helena — History of the changes in the vegetation — Cause of the extinction of land-shells — Ascension — Variation in the imported rats — Volcanic bombs — Beds of infusoria — Bahia, Brazil — Splendour of tropical scenery — Pernambuco — Singular reefs — Slavery — Return to England — Retrospect on our voyage. List of Illustrations Index Porto Praya—Ribeira Grande—Atmospheric Dust with Infusoria—Habits of a Sea-slug and Cuttle-fish—St. Paul’s Rocks, non-volcanic—Singular Incrustations—Insects the first Colonists of Islands—Fernando Noronha—Bahia—Burnished Rocks—Habits of a Diodon—Pelagic Confervæ and Infusoria—Causes of discoloured Sea.
Text from Project Gutenberg, public domain in the United States.