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.