June 1, 2010

Early English Colonists Faced Severe Drought

A new study has reinforced the idea that the first British colonists in America had to endure an unusually severe drought.

Jamestown in Virginia was the first successful English settlement in North America.

Chemical analysis of shells thrown away from 1611-1612 show that the James River was much saltier then than it is today.

This was due to decreased flow from surrounding freshwater rivers.

Rainfall must have been much lower when these oysters were growing in order for this to have been the case.

Researchers published their study in the Proceedings of the National Academy of Sciences (PNAS) journal.

The colonists selected Jamestown island on the James River as a secure location for their settlement.

The location had the advantage of a deep water channel that allowed the English ships to ride close to shore.

However, the island was swampy and overrun by mosquitoes.

The newest study suggests that the colonists could not have chosen a worse time to establish their settlements.

In 2006, Juliana Harding from the College of William and Mary in Gloucester Point, and colleagues, analyzed oyster shells retrieved from a well dug by the colonists.

The well was in use only for a short period before being converted into a rubbish pit.

The researchers looked at values of a particular isotope of oxygen laid down in the shells.

The levels of this isotope in oyster shells are controlled by the temperature and salinity of the water they grow in.

The team compared the isotope, known as oxygen-18, values in the 17th Century James River oyster shells with those from their modern day counterparts.

They discovered that the winter salinity of the river was much higher during the early 1600s than it is today.

This suggests that winter rainfall was considerably lower than modern levels. 

Previous studies based on tree rings and historical documents show that the arrival of the English colonists in Virginia coincided with a severe regional drought.

The years 1606 - 1612 were the driest in nearly eight centuries.

"Shortages of food and fresh drinking water, combined with poor leadership, nearly destroyed the colony during its first decade," the authors of the latest study write in PNAS.

About 80 percent of colonist died during this period.


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