Geological material like cobbles excavated from Jamestown can provide a surprising wealth of information about life in seventeenth century Virginia. Bermuda Limestone, as its name suggests, is not a locally found stone in Virginia. This type of limestone was formed millions of years ago as the Bermudian islands themselves were created. Two distinct deposits of this material exist in Bermuda, and it has been quarried and used in Bermudian construction and as an important export commodity since at least the late 17th century.
Prior to its commoditized use as a building material or export product, Bermuda limestone traveled to Jamestown as ballast, likely in the hulls of the ships, the Deliverance and the Patience, the two ships reconstructed on Bermuda by the survivors of the Sea Venture shipwreck. The presence of Bermuda limestone in various archaeological contexts helps archaeologists date various features on the site, because it would not have been present in Virginia prior to May 1610, when the Deliverance and the Patience finally arrive at Jamestown.
Ballast is used to lower the center of gravity and provide stability to boats and ships. The stones would have been redistributed as goods were loaded or unloaded onto or off of ships coming and going from Jamestown in the early fort period. With many Bermuda limestone cobbles lying about and not very much brick being produced locally in 1611-1617, the stones previously used as ballast had a second life as construction material for the colonists. Large cobbles of Bermuda Limestone, along with other locally sourced river cobbles were found forming the foundations of the ca. 1611 Row Houses and the ca. 1617 addition to the Row Houses placed on the eastern end by Governor Argall. These foundations have been outlined on the site today, using some of the original cobbles that once made up the architectural structure found by archaeologists underground.