Roots That Time Has Redefined

Field Report photograph, 1953 excavation of Franklin Mansion (Schumacher 1956:8).

Before there was an Independence National Historical Park there was archaeological research undertaken for what was to become the park. The first work (depicted above in an archived report) was conducted just over fifty years ago at the site of Benjamin Franklin’s Philadelphia mansion by the American Philosophical Society (APS) and the National Park Service (NPS).

At that time, APS undertook the excavation both as a memorial tribute to their founder (Franklin) on the 250th anniversary of his birth and as a research endeavor not unlike the expeditions APS sponsored, a half century earlier, that fostered Americanist Archaeology in its incipient period. NPS interest in the house site served the needs of the Master Plan for a national shrine to democracy (the soon to be Independence National Historical Park) which would include a park unit dedicated to local Philadelphia history and, in particular, to Franklin.

Franklin Court as the site became known (and interpreted) in Independence Park is a seminal urban archaeology site – and, until recently, the historical archaeology understandings that emerged in its early excavations have continued to shape the trajectory of Independence Park archaeology --and hence the understandings of early American history.

One of these very early dating assumptions about the Independence Park archaeological record has now been overturned. It involves the preservation of the archaeological evidence below ground in those areas with susequent building construction. The Independence Park Archive Archeological Records Collection reveals how this - an early understanding about the area's archaeological resource base --emerges and then transitions into a set principle determining the development and maintenance of archaeology in the park over time.

This past month I have been processing early archaeology-related administrative files in the Park Archives. In this collection I have come across what is likely the first time a recommendation is made regarding the state of the archaeological evidence buried below the city streets. It is a recommendation in a report detailing the results of the first episode of work at Franklin Court. It is written by Paul Schumacher, the archaeologist in charge of the 1953 and 1955 excavations at the site of Franklin’s mansion:

“It may well be that any future archeology of Old Philadelphia would give the best results by merely excavating underneath sidewalks and smaller streets or alleys. The properties where modern structures have been razed are very poor for archeology because of the deep basements these buildings usually had….”

I was already familiar with this report from earlier research on

Franklin-related archaeology that I conducted for the Benjamin Franklin Tercentenary Consortium (work commissioned as part of the federal celebrations to honor Franklin on the 300th anniversary of his birth in 2006). But coming across Schumacher’s report again in the Central Files –where they are evidence of park administrative history related to archaeology --made me see the report’s recommendations with a slightly different set of eyes.

I undoubtedly also saw this documentation differently today because of the recent understandings about urban historical archaeology gleaned from the excavation of the President’s House site in 2007. That recent park research revealed that the basements of nineteenth century buildings do not necessarily entirely obliterate the evidence of the colonial period landscape. This surprise finding in the case of the President’s House site has led to a rethinking about Independence Park's archaeological resources --namely, that the archaeological evidence can survive the ravages of time more than archaeologists thought it could.

But why was this survivability ever in doubt? The documents in the Central Files reveal that this (now often erroneous) assumption appears in the earliest days of the park’s creation when, in 1956, archaeologist Schumacher reports up the administrative chain-of-command with recommendations for future excavation in Old Philadelphia. Schumacher posits a logical conclusion at the time given the circumstances (the earliest excavation) but his recommendation reflected only limited exposure to the archaeological record in-situ (as it appears in the ground).

Schumacher was excavating an unusual example for colonial Philadelphia archaeology. The Franklin house was located in the middle of a city block. Deep basements are usually on the outside edges of the block along the streets but, in this case, a small street bisecting the block was built over top of the (razed) Franklin house remains. Nearly all of the foundation walls for Franklin’s house remained unimpacted by the street construction and by the two rows of homes that lined this street. Schumacher did explore parts of the adjacent house lots and one can only surmise that he is hypothesizing what might remain under the 19th century structures as he and the excavation team were not tasked with finding anything other than the Franklin ruins and were involved in following out the foundation walls that were encountered (leaving other areas largely unexcavated). The most relevant sought after discoveries at the time happened to be found under the street and sidewalks where their survival rate was very high.

In a future post I will report on other documents in the archive that show how this early recommendation transforms into a baseline assumption that holds for 50 years of Park development and management --until 2007 and the President’s House findings.

One note: It was likewise long assumed that archaeological evidence of the Native American experience was obliterated by the development of the city. In past decades, when archaeological artifacts were encountered during excavations they were considered to be 'out of context' (removed from their original place and time of deposit/use by subsequent city buildings). It is now understood, in part from the National Constitution Center excavations in Independence Park, that evidence related to the Native American past can be found in intact archaeological deposits in the city. For more on this change in thinking see the brilliant, online presentation, Native American Sites in the City of Philadelphia: Elusive but not gone. This web offering was created by archaeologist Doug Mooney and it is archived at the web site of the Philadelphia Archaeological Forum.


INHP Archive materials used in the preparation of this posting:

Jeppson, P.L. Historical Fact, Historical Memory: An Assessment of the Archaeology Evidence Related to Benjamin Franklin: Historical Archaeology research undertaken for the Benjamin Franklin Tercentenary Consortium, Philadelphia, Pennsylvania (2005)

Letter, Anderson to INHP Regional Director, Region One (Cox or Lisle), Feb. 20, 1953, [D18 FRCW as quoted in Grieff 1985:374]

Philadelphia National Shrines Report to the United States Congress (1947)

Schumacher, Paul. Franklin Court, Preliminary Exploration of Franklin Court Archeology Project No. 4, May-Sept. (1956)

See also:

Fowler, Don D. and David R. Wilcox. Philadelphia and the Development of Americanist Archaeology. University of Alabama Press (2003)

Philadelphia Archaeological Forum. http://www.phillyarchaeology.org/

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]

Could they have invented it?

"None of our employees have experienced any effects on their hearing from using the ultrasonic cleaner." (INDE Superintendent D.C. Kurjack, writing to the Regional Superintendent in September, 1961).

A wonderful discovery! While inventorying a file of History Office correspondence I came across a 1961 letter from the Park Superintendent that reports on "an ultrasonic cleaning device in use for cleaning archeological artifacts" (above right, click to enlarge). I wondered: Could it be that archaeologists working at INDE came up with this artifact processing method? Today it is common to find ultrasonic cleaners in archaeology labs. For example, the Independence Living History Center Archeology Lab down the street uses one for the first step in the washing of (suitable) artifacts. An ultrasonic cleaner loosens dirt caked onto artifacts minimizing the abrasion from brushes or picks.

The correspondence in this folder is not in chronological order and an earlier letter, dated 1960, is a request from a west coast archaeologist asking "Would [INDE] be kind enough to have Smokey [archaeologist Jackson Ward Moore, Jr.] clean these nails [from a Glacier Bay Cemetery] by his "magic process"..." (emphasis mine). I can check with Smokey and see if this reference is to the ultrasonic cleaning idea. If so, it would be the earliest date recorded for this method among these papers.

Further on in the file I came across a letter and its response relating to archaeologists at Mesa Verde National Park who sent a ceramic sample to INDE for a test cleaning. This correspondence too made me think the idea of ultrasonic cleaning originated at INDE. Then I found the clincher, a letter from an employee at Circo Ultrasonic Corporation (in New Jersey) asking how their device -- a Model PG 60 generator and 60 T transducerized tank of 1-gallon capacity -- had fared when put to this "unusual" task. The response from archaeologist B. B. Powell describes the INDE experiments trying different cleaning agents and the "excellent" results". Also described are the various applications experimented with (the processing of different categories of artifacts -- shell, ceramic, metal, etc.). The artifacts are mentioned as coming from the site of Franklin Court. I have posted some abtracts of that letter below (click to enlarge):

Lastly, I found something that makes it clear that this was indeed a new idea for archaeology!

In the file was an NPS Suggestion Form (10-63, 1955, 99219) with delightful 1950's-era graphics. This form, filled out with a date of October 1960, is a formal suggestion for the use of ultrasonic cleaning in archaeology laboratory work based on experiments done at Independence National Historical Park (click to enlarge):

This folder of History Office correspondence in the INDE Archives documents the administration of park archaeology circa, 1955-1975. As such, it contains artifacts of the archaeological process. In this case, among other insights, these two-dimensional artifacts document some important (forgotten) history about the field of archaeology. Specifically, these archived documents record the investigation of a new method for archaeological laboratory work that has since become a standard of practice. This advancement in the field of archaeology comes courtesy of INDE archeologists working on historical period sites.

The above referenced materials all come from Folder 1, of a box still being processed at the INDE Archives that is entitled "History Office Correspondence Related to Archeology".