by Andrew Bair

Archaeology

AT THE OLDEST HOUSE

By Andrew Bair

Archaeology is a lot of things, but the activity that figures most in the popular imagination is digging. At the same time, preserving the archaeological record—that is, all the physical remains of past people still preserved underground—is the primary ethical responsibility of all archaeologists. And therein lies the grand dilemma of archaeology: we want to learn more about the past, but archaeological excavation destroys the underground record of the past itself, which can never be studied exactly as it was a second time. Although archaeologists take painstaking notes to recover and preserve as much data as possible, once an archaeological site is excavated, that’s it.

Preservation of the archaeological record in the United States and around the globe is further threatened by population growth, economic development, and environmental changes, but perhaps most urgently by amateur artifact collectors digging holes looking for buried treasure. In 1966, the National Historic Preservation Act (NHPA) recognized the significance of the Nation’s finite cultural resources and provided a mechanism to ensure that federal agencies take into account the effects of their undertakings on historic properties and archaeological sites. Subsequently, State Historic Preservation Offices were established in each state to implement the stipulations laid out in the NHPA, and to the extent possible, adapt those regulations at the state level. In cases where federal and state regulations don’t apply, archaeological sites are vulnerable to imminent destruction, and permanent loss of data.

To balance the goals of collecting important archaeological site data while preserving these finite resources to the greatest extent possible, archaeologists have developed a number of best practices. At the outset, archaeologists coordinate preservation initiatives with the community to promote the development of laws, codes, and ethics that discourage the destruction of the archaeological record and promote preservation as a valuable tenet of community life. Next, as a research design is developed for a given project, the archaeological team identifies and prioritizes historic records, maps, community ethnohistory, reports of prior inves-

Harvard University graduate student Andrew Bair conducts a survey outside the Oldest House using ground-penetrating radar.

tigations, and warehoused artifact collections to develop goals, cultural contexts, and appropriate archaeological methods. Finally, central to the preservation commitment, whenever possible archaeologists use cool, non-destructive technology that allows them to study the archaeological record without digging it up.

The NHA has historically been a community partner committed to preserving Nantucket’s archaeological resources. With this nondestructive ethos in mind, in August the NHA initiated a new (and Covid-safe) research project at the Jethro Coffin House (16 Sunset Hill), that showcased the application of state-of-the-art, non-destructive archaeological technologies. Considered by some historians and scholars as the ‘Oldest House’ on Nantucket, the Coffin house was constructed in 1686 as a wedding gift for Jethro and Mary Gardner Coffin. After passing through the hands of private owners for over 250 years, the Jethro Coffin House entered the care of the NHA in 1923. Soon after in 1927, the NHA began a restoration of the house which defines its current appearance and character. Over the next two years, the chimney was raised and restored, wood sills were replaced, and a new masonry foundation was installed under the entire house. Other improvements included replacement of the burned lean-to-structure at the rear of the house using period structural elements from the nearby Paddack House, which was dismantled for this purpose. The house has been an element of the Nantucket Historic District since 1955, and was designated a National Historic Landmark in 1968. Today, the house is a highly visible symbol of Nantucket’s historical past and plays host to thousands of tourists every year.

The Jethro Coffin House is of great academic interest, having been studied by archaeologists, historians, and architects since the late nineteenth century. Understandably, most of this previous academic work has been concerned with the architectural features, history of ownership, and landscape siting of the house itself. But the Jethro Coffin House lies on a one-and-a-half acre parcel of land, which has received less archaeological attention. In 1975-1976, a test trench was excavated by the NHA Archaeology Committee near the northeast corner of the house that resulted in the recovery of domestic yard refuse dating to the eighteenth and nineteenth centuries (Jacobson et al 1986). Then in 1984, the NHA planned to construct a Colonial-period garden on the property. This prompted Dr. Elizabeth Little, vice chairman of the NHA Archaeology Committee, to propose a multi-disciplinary archaeological study of the property with the primary goal of locating remains of outbuildings, fence lines, garden plots, or other features to reconstruct land-use patterns and lifeways of the historic occupants. The project was funded by a technical assistance grant to the NHA from the Massachusetts Council on Arts and Humanities and coincided with the 1986 tercentennial year of the property. Methods included architectural and deed research, folklore, remote sensing using electric resistivity (non-invasive), archaeological testing, and paleobotanical analyses of soils. Taken together, the project identified areas of outbuildings and gardens, historic refuse disposal, brick and cobble paving, and contemporary disturbances and provided a systematic interpretation of the archaeological remains surrounding the house.

In the 34 years since the NHA completed archaeological studies at the Jethro Coffin House, archaeological technology has improved dramatically. As the NHA prepared to develop new, public-oriented educational initiatives on the property, the application of new techniques in the study of the house was a priority. Given what we already know about the history and archaeology of the house, and life on historic Nantucket more generally, we can revisit some basic questions with a new approach. What types of activities might have happened outside the house in the yard? Are there subterranean traces of historic structures that were not identified in 1986, such as a barn or other outbuilding that might give us new insights? Or how about a trash heap, or midden, which is one of the most exciting discoveries for an archaeologist?

To answer these questions and provide new data to compare with the 1986 survey results, in cooperation with archaeologists Andrew Bair (Harvard University) and Chad Gifford (Columbia University), and their colleague Colin Keane (also of Columbia University),

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surveyed the property around the Jethro Coffin House using ground-penetrating radar, or GPR for short. GPR is one of the exciting new ‘cool technologies’ that modern archaeologists use to understand what’s under the ground without needing to dig. A GPR is basically a big antenna that transmits radar energy into the ground. That energy will travel in a wave downwards until it impacts with something, like a buried stone wall or drainage pipe, that causes the wave to bounce back towards the surface in different ways. The GPR antenna listens for that return signal and records it. By dragging the antenna around on the surface of the ground, you can map where radar energy was reflected all around an archaeological site. At the end of the survey, and after a good deal of data processing, you can create a threedimensional map of an entire buried archaeological site without ever having to dig at all. GPR works a lot like how bats navigate in darkness using echolocation. Bats will emit a high-pitched sound and listen for the echoes it makes off objects in the night. They can visualize a three-dimensional map of their surroundings in their brain and use it to avoid trees and find their prey. GPR is exactly like this, except it uses radar waves instead of sound waves, and looks for archaeological features not tasty bugs. The GPR equipment used on this project was generously provided by Geophysical Survey Systems Incorporated.

The accompanying illustrations show this technology in play around the Jethro Coffin House. Specifically, the archaeologists are able to knit together hundreds of vertical slices of radar data taken side-by-side to render a three-dimensional map of the features that lay underground. While the archaeologists are currently processing the data and interpreting their findings, which they will deliver to the NHA this winter in the form of a formal report, they are pleased to present some very preliminary results. These, too, can be seen in the accompanying illustrations. It is too early to say for certain, but the GPR data suggest the presence of several buried archaeological features, possibly relating to garden plots and pathways. Interestingly, there are no obvious collapsed architectural structures with, for example, rectangular stone foundations. Regardless, the underground features that do appear in the data are

Jethro Coffin House Late 19th century photograph. NHA collection.

Ground-Penetrating Radar Results from the Jethro Coffin House. GPR can be used to create three-dimensional maps of the archaeological subsurface.

perfectly preserved underground, and will remain so for when archaeologists possibly return in the future for further surveys. Any new surveys in the open areas surrounding the Oldest House will need to connect these underground features with the archaeological work conducted at the site in 1986 by the beloved Dr. Little, as well as with what is known from the written historical records about life on Sunset Hill.

It is comforting to know that this history is safely preserved underground for future generations to similarly preserve or study in even more sophisticated non-destructive ways. The hope is that there are many other pockets of history preserved underground on Nantucket. However, if we are not careful, one day they will all be gone. It is our collective duty not just to better understand the archaeological record, but to protect it as well.