With world-wide attention focused on the issue of global warming, there has never been a greater need for reliable knowledge about climate change. In mid-November, a construction project on Useppa Island provided an opportunity to study both the climate and the culture of Pine Island Sound some 3,000 years ago.

two researchers stand next the exposed midden
Visiting archaeologist Julie Stein (left) takes measurements while FPAN archaeologist Kara Bridgman Sweeney sketches the exposed midden. Photo by B. Marquardt

Located about 3 1/2 miles west of Pineland, Useppa has been studied periodically by archaeologists since 1979. Several houses are to be built on the island by VIP Structures, and Lot III-17 was the first to be affected by heavy machinery. Specifically, some dirt was to be transferred from that lot and used elsewhere. A backhoe cut exposed shells and fish bones—the remnants of many fine seafood meals—as well as a few pieces of ancient pottery and shell tools. At the invitation of the owner, the Randell Research Center’s John Worth and Florida Public Archaeology Network archaeologist Kara Bridgman Sweeney, along with Bill Marquardt and visiting geoarchaeologist Julie Stein, studied the archaeological deposits and removed samples for further analysis.

Back at the laboratory, Bill Marquardt and Karen Walker water-screened the samples and selected materials for further analysis and radiocarbon dating. The dates indicate that people were on today’s Lot III-17 between about 3,200 and 2,900 years ago. Because shellfish and fish are sensitive to changes in the environment, careful analysis can reveal characteristics of water salinity and temperature. Thus, the well preserved 3,000-year-old Useppa debris offers an opportunity to track climate and sea-level changes during what is thought to have been a time of abrupt climate change, coeval with the development of the famous Poverty Point village in Louisiana.

Lot III-17 is owned by architect-builder David Nutting. Familiar with Useppa’s archaeological importance, and intrigued by the research potential, Mr. Nutting offered to share the costs of archaeological investigations. We plan to study past environmental conditions, seasonality, and subsistence.

To obtain information on environmental conditions 3,000 years ago, we will use a measurement of the amount of the oxygen isotope 18O in relation to 16O in the shells of surf clams. Different concentrations of these isotopes are absorbed by the clam while it is growing, depending on the temperature of the water. By collecting clams from the immediate area and determining the oxygen isotope concentrations in today’s water conditions, we will calculate a modern “baseline” temperature curve for comparison. Then we will do the same analysis for the archaeological clams, in order to discover the temperature of the water 3,000 years ago.

By “seasonality” we mean determining what seasons of the year people were living at this particular place. In our previous work, we have been able to correlate the alternating light and dark growth bands in the shells of modern quahog clams with the seasons of year. Like tree rings, the shell bands have a predictable annual pattern that can be used to interpret the times during the year that people collected these clams for food. Bay scallops can also provide insight into seasonality. Because scallops rarely live for more than a year, their size is a good indication of what time of the year they were harvested. Both the seasonality and temperature research will be done by the Florida Museum’s Irv Quitmyer and UF graduate student Meggan Blessing.

By studying the shell and bone remains, we will be able to determine food preferences as well as gain further insight into past environmental conditions. Undertaking the zooarchaeological analysis will be UF graduate student Michelle LeFebvre, assisted by UF undergraduate student Lauren Garroway. Michelle will identify the bones and shells to determine which fish and shellfish were being eaten 3,000 years ago, and what seasons of the year they were being taken.

We thank Mr. Nutting for his kind support, and we look forward to adding to our collective knowledge of southwest Florida’s environment and people.


This article was taken from the Friends of the Randell Research Center Newsletter Vol 6, No. 1. March 2007.