The following ran on the May 9, 2013, edition of National Geographic.com's Daily News. Paleontologist Louis Jacobs provided expertise for this story.
May 16, 2013
By Ker Than
A lost continent off the coast of Brazil may have been found, scientists announced this week.
Granite boulders dredged from the seafloor off the coast of South America two years ago could be remnants of a long-vanished continent, according to Roberto Ventura Santos, the geology director of Brazil's Geology Service.
"This could be the Brazilian Atlantis," Santos told reporters, adding that he was speaking metaphorically and not claiming to have found the legendary sunken world. "Obviously, we don't expect to find a lost city in the middle of the Atlantic," he said.
Santos and his team speculated that the granite—a relatively low-density rock found in continental crust—belonged to a continent that was submerged when Africa and South America drifted apart and formed the Atlantic Ocean about 100 million years ago....
Scientists earlier this year announced that they had found evidence of a drowned "microcontinent" off the coast of Africa, near the island of Mauritius.
Sand grains from Mauritius's beaches were found to contain fragments of the mineral zircon that were between 660 and 2 billion years old—far older than the island itself.
One theory is that the sand grains are remnants of Mauritia, a lost microcontinent that once existed off the coast of Africa and which was submerged when India broke apart from Madagascar about 85 million years ago.
Microcontinents are shards of land broken off from continents and supercontinents. The distinctions among the three aren't clear-cut, however, and labeling a landmass a continent or microcontinent can be arbitrary since there are no precise size requirements for each term.
New Zealand, for example, is actually part of a large continental structure that includes the Campbell Plateau. "It's not all that different in size from Australia, but because most of it is underwater, we call Australia a continent and New Zealand an island," Wysession said.
Microcontinents can also merge into larger structures. For example, "the north African edge of the supercontinent Gondwana broke up into slices like the pieces of an apple, and each of those [microcontinents] moved north to form southern Europe," explained Louis Jacobs, a paleontologist at Southern Methodist University in Dallas, Texas....