Oyster shells confirm drought in Jamestown

Studies of oyster shells taken from an abandoned well confirm that English colonists who settled on Jamestown Island in 1607 unknowingly picked the worst possible time for their endeavor, arriving in the midst of a drought nearly unprecedented in local history.

Research on tree rings had already shown that the colonists’ arrival in Virginia coincided with the beginning of the driest seven-year period in 800 years, and their written records — albeit scanty — confirmed that they encountered near-horrific privation.

The new findings suggest that freshwater flow in the James River was severely restricted and that the river water became too brackish for colonists to drink, forcing them to rely more heavily on wells that were also running dry. The findings also help to explain why the Native Americans were unable to help out with food: The Algonquins’ own food supplies were severely diminished.

“This is a real breakthrough, an independent confirmation of what was only based on tree rings and very little documentary history,” said archaeologist William Kelso of Preservation Virginia’s Jamestown Rediscovery project, who was not involved in the research. “It leads to a better feel for what it was like to be at Jamestown and the daily lives of these people.… Historians have given them a bad rap, saying they were lazy gentlemen.”

The group faced the normal difficulties of colonizing a new place, and were burdened by the fact that many of the settlers were indeed upper-class men with little training for their mission. They also brought limited supplies with them and received poor instructions from the Virginia Co. “If you stack up all the things against them and add in the drought, it was pretty severe,” Kelso said.

By the end of the first summer at the island, only 38 of the original 104 colonists were alive. By the end of 1610, only 60 remained out of 215 settlers.

The oyster shells in the study came from a 12-foot-deep well within the confines of the fort that was dug sometime after 1607 and that probably went dry about 1611, when colonists began using it as a garbage dump. The well was excavated in summer 2006, and the shells were sent to ecologist Juliana Harding of the College of William and Mary’s Virginia Institute of Marine Science at Gloucester Point, Va.

Oysters are a good archaeological tool because their life history is embedded in their shells. By measuring the ratio of isotopes of oxygen, researchers can tell when and where the oysters were harvested, as well as the salinity of the water in which they lived. The oyster shells were particularly abundant in the garbage midden because oysters had become an important food source as the colonists’ crops dwindled.

Harding and her colleagues, including geochemist Howard J. Spero of UC Davis, reported this week in the Proceedings of the National Academy of Sciences that the flow into the James River was reduced remarkably, leading the river to become much more salty as ocean water flowed back into it.

The delineation between fresh- and saltwater moved from downstream of Jamestown to a point more than 20 miles upstream. That meant the colonists could no longer drink the river water, Harding said. The salty water probably also seeped into their wells, contaminating them.

The movement of salinity had one benefit, however. As the ocean moved upstream, the breeding grounds of the oysters did so as well, providing additional food. But the shells show that the settlers were also forced to gather oysters from some distance away along the coast to supplement their supplies.

Harding saluted the endurance of the colonists in the face of such severe conditions. “They had no way of knowing that Virginia is not always like this” — so their persistence is a testimony to human optimism, she said.

thomas.maugh@latimes.com