Geo Positions: Archaeologist Embraces New Geospatial Tech for Old Sites
Joel Grossman is an archaeologist of more than five decades who has embraced the integration of geospatial technology since his earliest years of site discovery and examination. An independent consultant based in New York City, Grossman’s archaeological experience largely involves projects with uniquely challenging conditions. His professional career kicked off in 1965 as a young field supervisor while still in college. Grossman was awarded a Ph.D. in 1972 as a Fulbright Fellow from the University of California, Berkeley.
He went on to specialize in three areas. The first, Andean archaeology in Peru, was his primary area of training at U of C Berkeley. His Andean research included the discovery of a 3,500-year sequence of buried Pre-Inca cultures in the south-central highlands, which revealed early pottery making and early gold working dating to the 17th century B.C. He was invited by the Peruvian government to spearhead a United Nations Educational, Scientific and Cultural Organization (UNESCO) project to conduct field tests with various remote sensing technologies and train Peruvian archaeologists throughout Peru. After 1985, when it became impossible to safely continue work there because of the dangers the guerilla war posed. Archaeologist didn't go back to the area until around 2005.
Another area Grossman specializes in is prehistoric and historic Northeastern archaeology. He has directed a number of largescale historic excavations in the region, including the discovery of the Dutch West India Company block under Pearl Street in lower Manhattan. He says the project revealed the earliest Dutch occupation in New York, which dated from the 1630s through the 18th century.
Grossman’s third area of archaeological expertise has to do with the development of applied technologies, including geographic information systems (GIS). He has presented and implemented a series of GIS approaches in archaeology over the course of his career, which have been utilized in many projects. He calls it historic impact analysis as part of the initial site definition phase. When he started using the process, he would take low-altitude aerial photos, georeference them, then document and plot areas of identified surface remains and areas of disturbance visible in the photos from municipal maps. Then Grossman would overlay the areas of disturbance onto a project map and use a range of remote sensing applied technology —radar, magnetometers, conductivity — to make a map of the buried site. Finally, he would use GIS to subtract the historic impacts from areas of identified sensitivity to avoid wasting time and the client’s money excavating in disturbed areas.
“People thought I was very lucky,” he says, “because I kept coming up with discoveries, and that’s because I often used applied technology to produce high yields, 70 to 90 percent of the historic remains coming from high integrity deposits, artifacts and structural remains from only areas where the layer cake was still intact. I'm about as lucky as an F-16 pilot with an aircraft in the cross-hairs.” Grossman says he has witnessed many significant improvements since the 1980s, starting with the availability of microcomputers, which allowed control of large amounts of data. Other notable advancements that stand out in his mind include the ability to record 3D location in real time to the precision of a 10th of an inch, dedicated GIS packages that simplify data processing, and the availability of airborne LiDAR for discovering lost cities under forest cover. He says a very robust amount of geospatial technology and strategy has become commonplace in archaeology since he started, and he hopes simplification and integration will continue on.
Q. What do you do for a living?
A. I’m an archaeologist who’s a senior project director.
Q. What is your favorite tool to work with?
A. I would say air photo analysis and reconnaissance, very much like intelligence gathering, is one of the more exciting tools we can use. The other tools that I find very revolutionary have to do with the implementation of remote sensing capabilities — radar, magnetics, conductivity — to make maps of buried cities. Ground-based LiDAR has brought significant advantages to the challenge of capturing high-quality, true-color, coordinate-precise renditions of sites or monuments.
Q. What is the toughest challenge you face?
A. I’ve dealt with problem situations. I’ve dealt with unexpected discoveries under construction. That’s a phrase in government — “discovery under construction.” That is where they have done all of the environmental compliance up front, they spent years studying a project, they did archaeological surveys and said nothing was there, and then they start construction and they hit King Tut, which is what happened [to me] in New Brunswick, N.J. That project used ground penetrating radar (GPR) to produce a color-coded underground radar map of the buried colonial settlement. Other projects were not emergency responses, but instead were part of a carefully orchestrated, staged compliance process. In lower Manhattan, I directed the investigation of the 17 C. Dutch West India Company block at Pearl and Whitehall streets. Archaeologists knew there was going to be something down there because other people had found early pottery and artifacts, generally during construction, in lower Manhattan. Previous digs had documented the survival of late 17th and 18th century remains. We gambled that the Pearl Street site contained preserved, early 17th century deposits and structures from the first decade of the settlement.
That was a challenge because it was in lower Manhattan and we had to stream dump trucks coming into the Pearl Street area to take out 8 feet of fill from a block so we could get down to the 17th century settlement, found buried and protected under the deep brick basement floors of 19th century row houses. The buried colonial 1630s settlement was found intact with cobblestone floors, stone foundations, cisterns and yellow brick structures, and over 40,000 artifacts. That was a challenge because it was in a high-density urban area where there was very severe financial stress on the developer, on the agencies and on the archaeologists to use whatever techniques possible to expedite the project. It was done on time and on budget.
In addition to working in complex urban environments, I’ve dealt with politically sensitive areas. One of the most challenging had to do with the discovery of Native American burials in upstate New York under a much-needed federally funded water treatment plant site. That precipitated months of negotiations between the federal and state agencies and the six nations of the Iroquois League who, working together, were able to come up with a protocol that respected the cultural and spiritual concerns of the Native Americans, and addressed the scientific and legal requirements for the excavation and study of human remains, often seen as two conflicting goals. They worked for months to expose and then document, insitu, the human remains without taking them to a museum, laboratory or university. Then, once they were documented, they were reburied in protected federal land near the project area bordering the Hudson River. That was a major challenge and I consider that one of my most successful negotiations. I had to go against the mainstream of archaeology to resolve this challenge of doing justice to the human remains and the sensitivities of indigenous peoples. Now proper treatment and consultation with Native American groups are mandated by federal law. Then it was not, and I had to think on my feet.
The third major challenge that highlighted my professional experience had to do with developing the capability to do high-capacity, high-quality archaeology in contaminated areas — arsenic, cadmium, lead, radioactivity, often under adverse conditions. That was under the Superfund program. All team members were trained in HAZMAT procedures. We worked in protective Tyvec suits and high-capacity respirators. We developed computer-based archaeological techniques to circumvent the limitations of traditional approaches. We used applied technology to expedite the site definition and data recovery processes. One aspect of my work had to do with timing of the project, or doing work under deep winter conditions. Construction generally takes place only in fair weather. They shut down when it rains and they also shut down during winter. Thus, most of my excavations were scheduled for deep winter months. So what we developed was a series of inflated, metal-reinforced shelters, starting with greenhouses with double layers of plastic, which formed an air cushion or an air buffer, to keep the heat in. Then we de-watered groundwater and pumped in hot air from giant heaters that we brought on site to keep the artifacts and archaeologists thawed. In fact, most of my excavations took place in the winter time. We had to develop geospatial techniques to record under these low-altitude shelters. For the Dutch West India Company site, we actually built stereoscopic camera mounting systems that ran on rails over the excavation, taking stereo pictures as we worked. At West Point Foundry, a Superfund site, other innovations involved the adaptation of single-camera RolleiMetric metric camera system to capture a 3D photogrammetric record of the excavated site under the winter shelters. The camera was mounted and controlled with a custom-built robotic tripod with hardwired controls to a television camera to guide the metric camera.
Q. What is the biggest lesson you’ve learned?
A. I think the major insight that I have garnered from my experience has to do with the role of applied technology in expediting complex planning situations or delays or interruptions in ongoing construction; the need for integrated technology at multiple levels to address largescale project requirements. These projects are 25 to 50 scientists for three to six months or several years to analyze and report on the findings.
Q. What advancements would you like to see made?
A. The development of software capabilities that simplify the mapping of air photo remote sensing data. Those are efficient mapping programs that, very often, the commercial packages are so large and so overbuilt with many capabilities that they’re difficult to deploy because you need specialists in GIS. Instead of being able to train scientists to use it, you need a GIS person to run the complex programming, whereas the actual use of the GIS may be limited to three or four functions necessary to georeference, for example, digital scans of air-photo coverage. The integration of capabilities is one of the trends I’ve seen in applied technology in archaeology, where everything we began to innovate with beginning in the 1980s was an independent capability or package that was not integrated with other software. We would collect angle and distance with the early transits and then we had to convert them into coordinates and we did that ourselves. We had to write our own programs in BASIC to convert angle and distance readings from early computer-transits to real-world coordinates. That is now integrated into the capabilities of total stations. So as you shoot the points of interest, it is automatically converted in whatever coordinate system you want. What used to be independent is now integrated. So the trend I’d like to see is the continued integration of geospatial techniques into effective, simple-to-use and cost-effective packages.
Q. What are your keys to success?
A. One of them is being open to innovation and the application of new techniques to an older field like archaeology. [Another is] the ability to tinker with hardware and software, and to develop capabilities that are not commercially available. The third area that makes a difference is in the planning of large-scale projects and the integration with the community and/or federal and state agencies. Often, my key to success has to do with long-term negotiations that are expedited and enhanced because of the availability of applied technology, which reduces the time frame and reduces ambiguity.
In archaeology and in other disciplines, you win with definition, you lose with ambiguity. So all of my work has been focused on developing the integration of capabilities into simple-to-use, cost-effective packages. The other area has to do with integrating the science with outreach to the public and to regulatory agencies so you can play in their back yard. Very often it’s difficult for universities to be the centers of high archaeological capabilities because of traditional boundaries between different departments. One of the keys to my success has been the integration of diverse scientific disciplines (terrestrial LiDAR; soil chemistry; geophysics; engineering; GIS marine and terrestrial remote sensing; photogrammetry; forensic anthropology; computer-based, real-time, 3D-quantified data control; ethnobotany; conservation; and paleo-environmental reconstruction) so they work together smoothly. So, through the integration of applied technology, the goal is the ability to provide enhanced levels of definition in restricted time frames, under adverse conditions.