Tree Rings Reveal Clues To Mystery Of Missing Colonists

Tree rings may tell a tale that for four centuries has eluded historians - just what caused the first British settlement in the New World to vanish and placed the second on the verge of extinction.

New research shows that the worst drought in 800 years may be what drove more than 100 colonists of Roanoke Island, in what is now North Carolina, from their settlement. The entire colony mysteriously disappeared between 1587 and 1590, when a supply ship returned to find no trace of the settlers but the word "Croatoan" carved on a tree.

Another severe, and longer, drought may have brought on the "starving time" of 1609-10 for the residents of Jamestown, the first permanent English settlement in America, in what is now Virginia.

Researchers from two institutions studied growth rings in trees of the region to discover the droughts. The scientists described the new work in today's issue of the journal Science.

Some historians have attributed Jamestown's troubles, and the loss of the Roanoke Island colony, to poor planning by the British. But the new work suggests there wasn't much the settlers could have done to stave off the disasters.

Evidence for the drought is preserved in the growth rings of giant bald cypress trees that have lived for centuries in the swamps of the southeastern United States. Thicker rings indicate better growing conditions.

David Stahle of the Tree-Ring Laboratory at the University of Arkansas in Fayetteville has been using these trees to piece together a climate history for the region.

"It's the most objective source we have so far," said archaeologist Dennis Blanton, who studies the Jamestown colony.

Only 38 of the original 104 settlers were still alive a year after Jamestown's founding in 1607. Of the 6,000 colonists sent to the settlement between 1607 and 1625, about 4,800 died, Blanton said.

Letters and diaries from the settlers paint a dramatic image of failed crops, fouled drinking water, disease and malnutrition.

The Jamestown colonists were also holding an uneasy peace with Indians. Captain John Smith wrote that the local tribe appeared to be holding back from giving the hungry settlers corn.

"So I had a hunch that there may have been a drought going on," said Blanton, of The College of William and Mary in Williamsburg, Va.

He called the Arkansas lab and asked it to piece together a climate history for the Jamestown area.

The tree rings confirmed his hunch: The drought that lasted from 1606 through 1612 in that region was the worst seven-year drought during the entire period between 1215 and 1984, Blanton, Stahle and colleagues wrote in Science.

A second, more severe dry period also stood out in the data.

"When we noticed 1587 was a drought, it was like, `Hey, that's Roanoke, that's the lost colony,' " said Matthew Therrell, who works in the Arkansas tree-ring lab.