An unusually long-lasting drought plagued early colonists of the first permanent British settlement in North America.
Oyster shells from Jamestown reveal that colonists had to cope with an unusually long drought.
Previous studies based on tree rings and original documents back up this finding.
Many accounts of Jamestown's early settlers chronicled the long-lasting drought.
Oyster shells excavated from a well in Jamestown, Va., the first permanent British settlement in North America, bolster the notion that the first colonists suffered an unusually deep and long-lasting drought.
The shells reveal that water in the James River near the colony, where many of those oysters were harvested, was much saltier then than along that stretch of the estuary today, says Howard Spero, a geochemist at the University of California, Davis. For the water to have been so brackish, river flow must have been slacker compared to today, a sign that precipitation was dramatically lower when those oysters were growing. Spero and his colleagues report their findings online May 31 in the Proceedings of the National Academy of Sciences.
Jamestown was established in 1607. The early years weren't easy: Many accounts of Jamestown's early settlers, including journal entries and letters home, chronicled the drought. So did the region's trees, Spero says. Previous studies based on tree rings and original documents revealed that the first colonists' arrival coincided with the beginning of a drought that included the driest seven-year interval in almost 800 years.
"It was interesting trying to figure out what was happening in the colony at a time when 70 to 80 percent of the colonists were dying," Spero says. "This was 'CSI Jamestown'."
Now, oysters independently confirm the tale from trees and historical accounts, comments William M. Kelso, an archaeologist at Preservation Virginia's Jamestown Rediscovery project who was not involved in the study. "We're getting a consistent story from science and the humanities," he notes. "It's pretty fantastic."
The telltale oysters were unearthed from a well that sat within the fort at Jamestown, about 100 yards from the river. Among other material dumped into the well, the shells came from three distinct layers up to 3.5 meters (11.5 feet) deep. The well's water level originally sat deeper, at a depth of about 4 (13 feet) meters, so Spero and his colleagues suggest that the settlers abandoned the well -- which either ran dry during the drought or was infiltrated by salty groundwater -- and converted it into a trash pit.
Historical accounts suggest that settlers dug the well sometime between 1609 and 1617, but items unearthed from the well narrow that window considerably, Spero says. For one thing, ratios of different forms, or isotopes, of oxygen in the shells suggest that the mollusks were harvested before the drought ended in late 1612.
One archaeological artifact found beneath the oyster shells, a ceremonial item linked to a particular nobleman from England, couldn't have been present in Jamestown before he arrived in June 1610 and probably wouldn't have been discarded in the well until after that nobleman's return to England in April 1611. That data, plus the pattern of isotope variations in the oyster shells -- which reveal the season when those shells were harvested -- hint that the mollusks were gathered and eaten between late fall 1611 and summer 1612.
Analyses of the oyster shells have raised another mystery, Spero says. The oxygen-isotope ratios in the middle layer of shells are substantially different from those in the upper and lower layers, which other data suggest were gathered locally. That disparity indicates that the middle oysters, which were shucked in March and April of 1612, were gathered elsewhere, Spero says. Further analyses of trace elements in those shells should reveal whether the oysters were gathered in another part of the James River watershed or were collected elsewhere along the Mid-Atlantic coast and brought to Jamestown by sailors on an English supply ship.