Oyster shells have been found in almost every single context at Jamestown. They were an abundant local resource, with the colonist Francis Perkins describing the James River in 1608 as being “very beautiful and wide, but full of shallows and piles of oyster shells.” The Englishmen were already familiar with oysters as a food before they arrived in Virginia but they came to rely upon them heavily, especially in the early years of the fort when food was often in short supply. In an attempt to reduce pressure on the limited food available in the fort in May 1609, John Smith, the president of the colony, sent a group of settlers away from the fort to live “upon the oysters for the space of nine weeks.”
Oyster shells serve as small data recorders of the waterway in which they develop and grow. Similar to tree rings, the layers of an oyster shell can be analyzed to investigate past soil salinity levels and the amount of carbon in the water at the time the oyster was growing, which can determine the season in which the oyster was harvested and what the local environmental conditions were at the time. An oyster’s size can indicate not only how old it was when it was harvested, but also can help researchers reconstruct what the 17th-century reef system may have looked like. Intertidal and densely-packed reefs, or farther out in a channel and loosely clustered reefs, correlate to the growth and size of the oysters at each place. In the absence of modern diseases and environmental pressures, the oysters harvested by the Jamestown colonists grew significantly faster than modern oysters do (Harding, 2008).
Research on oyster shells excavated by Jamestown archaeologists has demonstrated that in the earliest years of the colony, oysters were gathered from beds that grew relatively close to the fort itself. Oysters from Pit 5 were likely harvested from a large reef system only about 12 miles east of Jamestown Island. As may be expected, the colonists harvested the largest ones they could find. Oysters from this pit occasionally measured as long as 145mm – almost 6 inches long! They would have been gathered from the top of the reef at low tide, or by wading out into shallow water. This was relatively easy work to meet nutritional needs (Schmidt and Haven, 2004).
Analysis of oysters found in the colony’s first and second wells compared with the Smithfield well (ca. 1621-1624) showed that a drought occurred between 1606 and 1612. This event had a significant effect on the oyster populations, amplified by new and more intensive land use patterns by the colonists as tobacco became a booming cash crop. Decline in the colonists’ mortality rates as the 17th century progressed combined with continual immigration from England to Jamestown meant that more food was needed to support a growing population. This need, combined with increasing familiarity with and control over the landscape led the colonists to begin seeking oysters farther afield and bring them back to the fort to be eaten (Grimm et al., 2017). Tens of thousands of oyster shells found discarded among other trash in James Fort’s second well, harvested during the winter of 1611 through spring of1612, have been sourced to two different oyster bed locations. Some came from a location close to Jamestown Island, but other oysters were transported from a downriver location closer to where the Chesapeake Bay and James River meet (Harding et al., 2010).
Oysters were not only an important food resource, but their shells were also used in building construction at Jamestown. Their use in construction highlights a change over time in available resources and the adaptation necessary to continue the development of the Jamestown colony. In England at the time of Jamestown’s founding, chalk and limestone were readily-available resources and were relied upon as a source of lime, which was essential in making mortar, plaster, and whitewash. These were both imported to Virginia and used in some of the earliest James Fort structures, notably in the mortar found in the kitchen and cellar which contains two brick ovens, probably the earliest brick masonry in America.
However, chalk and limestone were not largely available in Virginia, and once imported resources had been used, a new ingredient was needed to provide the binding agent of lime. Conveniently, burned and fragmented oyster shells mixed with water served this purpose. Pits at James Fort, containing either large amounts of burned oyster or remnants of unused mortar, are evidence that the construction of lime ricks and subsequent mortar mixing was probably occurring close to the construction of buildings which required mortar or plaster. Governor Argall’s addition notably contained both oyster shell mortar and whitewashed plaster, indicating that by 1617 oyster shell was relied upon for construction occurring at James Fort.
Grimm, Brittany L., Howard J. Spero, Juliana M. Harding, Thomas P. Guilderson (2017) Seasonal radiocarbon reservoir ages for the 17th century James River, Virginia estuary. In Quaternary Geochronology 41: 119-133.
Harding, Juliana M., Roger Mann, and Melissa J. Southworth (2008) Shell length-at-age relationships in James River, Virginia, oysters (Crassostra Virginica) collected four centuries apart. In Journal of Shellfish Research 27(5): 1109-1115.
Harding, Juliana M., Howard J. Spero, Roger Mann, Gregory S. Herbert, and Jennifer L. Sliko (2010) Reconstructing early 17th century estuarine drought conditions from Jamestown oysters. In Proceedings of the National Academy of Sciences 107 (23): 10549-10554. https://doi.org/10.1073/pnas.1001052107