The ring-shaped coral islands known as atolls, like this one in the Maldives Islands in the Indian Ocean, may trace their formation to sea levels repeatedly rising and falling over hundreds of ...

Almost 200 years ago, during his voyage on the HMS Beagle, Charles Darwin charted reef systems around the world, many of them with astonishing accuracy. On the basis of his observations, he formed a ...

DIEGO GARCIA is a typical atoll; a narrow strip of land varying in width from a mile to 30 yards, nearly completely encircles a lagoon of irregular shape. The lagoon is open to the ocean towards the ...