Their study shows that the iron-rich dust from the vast African desert, carried 8,000 kilometers through the atmosphere across the Atlantic, nourished the specialized bacteria that produced the calcium carbonate to build up the Bahama islands over the last 100 million years.
Led by marine geologist Peter Swart, the scientists found high concentrations of two trace elements characteristic of Sahara's sand in samples of the sea floor along the Great Bahama Bank.
The sediment there was created by cyanobacteria, which, Swart says, "need 10 times more iron than other photosynthesizers because they fix atmospheric nitrogen."
That process produced the calcium carbonate that now surrounds the Bahama island chain.
Their research appears in the journal Geology.