Bruce Rueger has sunk to new depths in his search for answers.
A senior teaching associate in the Department of Geology, Rueger was puzzled by the quartz sand he was finding in sediments from core samples of Bermuda ponds and marshes. The source of the sand was an enigma: the islands of Bermuda are composed of limestone above sea level and volcanic rock below sea level. None hasany significant quartz in it. At the annual meeting of the Geological Society of America, Rueger presented evidence suggesting that North American birds may be transporting significant amounts of sand to the islands; a practice, he says, that probably has been occurring for thousands of years.
The sand has been most thoroughly studied in a core from Lover's Lake in Bermuda. After ruling out human activity as a source of the sand, Rueger concluded that some natural process had to be responsible. Normal winds are far too weak to carry sand-sized materials over such a distance, and hurricane winds typically originate over water, not land. Rueger suspected birds as possible carriers since a number of bird species migrate between the islands and the American mainland. He analyzed the stomach contents of 15 bird species from Bermuda and found quartz grains in eight of them. Of these eight, five-- the ruddy turnstone, the common snipe, the sora, the common moorhen and the fulvous whistling duck--are common migratory visitors.
Rueger calculated that it would take between 15,000 and 62,000 migratory birds visiting Lover's Lake each year to account for the sand he found in the lake bed. A core sample taken from a depth of 78 centimeters, approximately 3,800 years old, contained the same quartz crystals. Some scientists speculate that the birds have been depositing sand in the lake for the island's entire 500,000-year history.
The startling discovery generated a rash of media interest. Rueger told The Ottawa Citizen: "It's cool that you can put those kinds of fingerprints on minerals--and exciting that other people find it interesting."
