A study led by scientists at the University of São Paulo (USP) in Brazil has shown that the Rio Grande Rise (RGR), a possibly continental basaltic plateau and chain of seamounts now submerged in the South Atlantic Ocean some 1,200 km from the coast of Brazil, was once a giant tropical island, rich in minerals and covered with vegetation. Geologists have dated sediments from the formation to between 45 million and 40 million years ago.