New Methods -- and forthcoming Records!...

Mended bowl (left), 3D digital scan of same vessel (right).

Computer-assisted vessel reconstruction technology is in the works!

INDE ceramic artifacts are the data set for this research and technological development. Once operational, this new technology will have significant implications for archeological artifact mending, collections management, and site interpretation.Records from this research and development project will be archived as part of the INDE Archaeological Records Collection.

Beyond discovering, preserving, and interpreting American history, Independence Park's archaeologists and archaeological sites have helped to shape the discipline of archaeology. Records in the Park's Archives document the creation and testing of various field and lab methods that have gone on to become a standard part of archaeological practice. This includes the ultrasonic cleaning of artifacts, early application of electrolysis to conserve metals, and various geophysical surveying methods including metal detecting and proton magnetometer prospecting.

As the field of archaeology continues to grow and change the archaeology at INDE continues to contribute new methods. All such developments of course generate a trail of documentation that become part of the archived archaeological records collection.

I blogged previously about the cutting-edge, geospatial survey techniques used at the President's House site in 2007. In that development, Erdman Anthony undertook a 3D laser scanning survey that produced a highly detailed and accurate map of the excavation. By shooting 4,000 laser points a second, the laser technology also created enhanced visuals of the discovered ruins that are useful for interpreting the site.

Now a new project is underway at INDE that will have significant implications for archeological artifact mending, collections management, and site interpretation. It involves the development of computer-assisted vessel reconstructions. Once operational, this technology will allow for more efficient laboratory work and will produce a significant time and money savings. Computers (not just people) will be able to match up the decorative markings on, and the shapes of, ceramic fragments so as to 'piece back together' broken vessels. Such vessel reconstruction is a vital first step in the laboratory processing of artifacts. Speeding up this phase means faster advancement to the analysis phase of study (as artifact identification precedes site analysis). Computer-assisted vessel reconstructions will furthermore allow for remote research capabilities as a collection of ceramics will be able to be studied off-site via digital proxies. Moreover, the digital images created during the reconstruction process will be a useful resource for virtual history presentations.

This particular research and development is part of a three-year effort by researchers from Drexel University. The work is supported by a grant from the Information Integration and Informatics division of the National Science Foundation [NSF no. o803670] entitled, “The 3D Colonial Philadelphia Project—Digital Restoration of Thin-Shell Objects for Historical Archaeological Research and Interpretation”. Principle Investigator Dr. Fernand Cohen (computer vision; Electrical and Computer Engineering) and co-PI's Dr. Ko Nishino and Dr. Ali Shokoufandeh (computer vision; Computer Science), Dr. Patrice Jeppson (archaeologist, Visiting Researcher: Media Arts) and Dr. Glen J. Muschio (anthropologist and media art expert; Media Design) are working with NPS Archeologists Jed Levin, Willie Hoffman, and Deborah Miller.

The project is using the ceramic artifact collection recovered from the National Constitution Center site as a data set. Several Drexel University graduate and undergraduate students are assisting with the research by making 3D scans of mended --and then unmended -- ceramic vessels in the Independence Living History Center Archeology Lab while other students at Drexel are writing computational algorithms for developing the new technology.

Drexel Computer Engineering Graduate student Ezgi Taslidere and Undergraduate, STAR Scholar, student David Myers scan pieces of a pedestaled saucer.

Undergraduate, STAR Scholar Program, student Girish Balakrishnan and Dr. Glen Muschio (Program Director, Digital Media Antoinette Westphal College of Media Arts & Design Drexel University) examine the 3D camera images.

Dr. Ali Shokoufandeh and graduate student Patrick Smith photograph decorated ceramic fragments in preparation for testing computational procedures for pattern matching.

Not just new methods but new methodologies....

In assisting the Drexel University grant project, Independence Park, through its archeology program is engaging with community partners. This and other civic engagement activities at INDE are some of the developments transforming archaeology's stewardship and interpretation methodologies. For example, the recent President's House site excavation was undertaken in response to local community group concerns and was conducted in partnership with the City of Philadelphia Office of the Mayor. Likewise the James Dexter site excavation was a project which emerged in consultation with descendant church leaders from the Episcopal Church of St. Thomas and the African Methodist Episcopal Church (Mother Bethel). Both these INDE projects have been used as case studies exemplifying the NPS Directive on Civil Engagement and they are considered best examples of Public or Community Archaeology.

This blog project is one small step in developing archaeology's stewardship and interpretation methodologies. It aims to help the INDE Archives make the Archaeological Records Collection more accessible to researchers and the interested public.

Another ‘First’?!

The Archives at Independence Park have yielded yet another discovery related to the history of American archaeology! The Park’s buried cultural resources were used in the early testing of geophysical surveying methods for archaeological research!

These methods --which are a routine part of practice today – involve the use of non-invasive, non-destructive, physical sensing techniques that detect buried archaeological evidence. The resulting underground 'site imaging' is useful for mapping archaeological remains as they exist in the ground. These geophysical studies also guide archaeologists in planning their excavations. More recently, the resulting map images are employed in interpreting historical landscapes to the public.

Correspondence archived in the Park’s Central Files (Box 23, Folder H22: Archeology and Historical Research - Independence Square) indicates that in 1961, Dr. Elizabeth Ralph, then of the Physics Research Laboratory at the University of Pennsylvania, requested permission to conduct surface tests and demonstrations "with a proton magnetometer and other archaeological searching equipment” on Independence Square.

Ralph is today credited with pioneering the use of geophysical surveying in American archaeology. Her research developed and improved several instruments for underground exploration. The archived Independence Park archaeological documentation indicates that she tested some of these devices, and trained others in their use, using the historical archaeology remains buried in Independence Square.

At the time, Ralph was researching the archaeological potential of geophysical methods then being used in the fields of geology, engineering, and mineral exploration. She experimented with electrical resistivity instruments that used wave projections to detect metals in the ground (metal detecting) and seismic detectors that employed wave propagation to find soil layer changes. She advanced archaeology's use of sonic detectors and magnetic contrast research, building upon nuclear science research that had led to the development in Europe of proton magnetometers and varian rubidium magnetometers. These instruments allowed for “archaeological prospecting” by measuring very small energy level changes in protons when they are subjected to magnetic charges. (Click on this circa 1965 image of Ralph to link to The Electronic Detective and the Missing City, an article written for Expedition [Winter 1965, 7(2):4-8], the magazine of the University of Pennsylvania's Museum of Archaeology and Anthropology. Ralph went on to become Director of the Museum's Applied Science Center for Archaeology).

Ralph's magnetometer studies were designed to pick up magnetic contrast readings between ancient buried walls and the earth around them. She crossed paths with the archaeology in Independence Park in 1963, when, in preparation for Old World (European-based) research, she tested instruments, and trained their operators, using the buried ruins of colonial and federal era America.

(Photo: Archeological test trenching at Independence Square in 1959. Early excavations at the square provided information about the historical landscape south of the State House [Independence Hall]. [Image: INDE Archives].)

Letters archived in the Central Files record that Ralph was provided with park archeology maps and drawings to assist her in her equipment testing. These documents detailed the locations of 18th and 19th century house walls and garden pathways, and late 19th and early 20th century utility pipelines. These had been discovered in the 1950's during archeological investigations at Independence Square.

It is unknown at this time (at least as far as my cursory research indicates) whether Ralph’s instrument testing at Independence Park produced any additional research findings. This may have occurred -- although her objectives involved determining whether the instruments could reliably re-locate already identified features. And if so, it is quite possible that any results were not recorded for historical archaeology’s sake: Beyond being another kind of specialist, there was no field of historical archaeology yet in 1963--although historical sites had been investigated archaeologically for decades for historical architecture needs (even recently in the creation of Independence Park), and the first Conference of Historic Sites Archaeology had only just met for the first time (in 1962). The archived correspondence does report that Ralph offered her assistance to the Park archaeologists. If early geophysical findings do exist from this time they could be of use to present day archaeological recovery efforts at Independence Square.

Today geophysical studies are commonplace in archaeology, including at historical archaeology sites in Independence Park. For example, ground-penetrating radar studies were undertaken in recent years at both Independence Square and the Deshler-Morris House property prior to restoration/renovation activities. Systematic collection of geophysical data for spatial studies has also included the use of other new technologies: In 2007, a geospatial laser survey was used to record the excavated ruins discovered at the President’s House site.

(Photo, top: Kitchen sub-cellar, President's House complex. Bottom, 3D laser scan survey image made by Erdman Anthony company [ Photos: Jed Levin, INHP].)

Beyond the park boundaries, geophysical archaeological studies make use of drones and satellites to conduct infra-red and other light spectrum scanning that penetrates the earth’s crust (and the forest canopy) to locate evidence of past human activity (e.g., roadways, trade routes, lost cities, sunken cities).

Such options were yet to be imagined when, in October 1962, the journal American Antiquity reported on “new developments in [archaeological] field and laboratory research” from Independence Park. This included a notice that “the first extensive field tests following preliminary testing at Independence Square, Philadelphia, were made of a new sonic echo underground searching device developed by Elizabeth Ralph and her associates at the Physics Department at the University of Pennsylvania” (emphasis mine). This same "Current Research" column also remarks on the implementation of the new method of “sonic cleaning of ceramic and glass pioneered by B. Bruce Powell and Jackson W. Moore for the National Park Service at Independence Hall" (sic). I blogged on this other Park 'First' in July after coming across archived correspondence related to experiments with ultrasonic cleaners for the processing of archaeological artifacts.

Once again, this finding aid project has uncovered ‘buried’ history about the role Independence Park archaeology has played in the development of American Archaeology.

Other...

[For more on early archaeology in Independence Park]

Cotter, J.L. (1960) Digging an Historical Shrine: Philadelphia’s Independence Park. Expedition 2(3): 28-32.

[For more on the history of magnetometer use in historical archaeology]

Sillimen, S., P. Farnsworth, and K. Lightfoot (2000) Magnetometer Prospecting in Historical Archaeology. Historical Archaeology 34(2)89-2009.

[For more on the geospatial laser surveying of the President's House]

Merritt, B., Surveying Technology, 3D Laser Technology: Delivering Real Time Examples and Virtual Demonstrations. Government Engineering, May/June 2008: 37-39. [Erdman Anthony company web page]