January 29, 2009
AIA Lecturer Brendan Foley
After receiving his undergraduate degree from the University of New Hampshire, Brendan Foley continued on to Tufts University where he received his M.A. in History. He then attended the University of Southampton where he received his M.Sc. in Maritime Archaeology and then Massachusetts Institute of Technology where he received his Ph.D. in the History and Archaeology of Ancient Technology. Foley is currently a research associate at Woods Hole Oceanographic Institute. He specializes in archaeology in deep water, classical Greece, nineteenth-century maritime history and naval engineering, and advanced technologies and methods for archaeology. Foley has 17 years experience in the field and has extensive experience with remote sensing and remotely operated vehicles.
After starting your academic career as a history major, what sparked your interest in maritime archaeology?
When I first started, I liked the idea of combining scholarship with physical activity like boating and scuba diving. I then realized that maritime archaeology provides access to data that is otherwise unavailable. Shipwrecks deliver the real stuff of ancient trade, in a way that textual evidence often cannot. And of course, for the prehistoric or protohistoric periods, archaeology is the only way to gain insight into our predecessors’ lives.
What are some major challenges underwater archaeologists face that excavators on land don’t have to contend with?
Probably the biggest hurdle we face is the remoteness of underwater sites. Of course, it is difficult to get to many places on land, too, but underwater work invariably entails more complicated logistical planning. This is true whenever we’re working on sites in very deep water that require underwater robots or human occupied vehicles, but the situation is the similar even when we’re practicing “traditional” underwater archaeology with scuba gear. Another problem is limited visibility underwater. There is no underwater equivalent to aerial photography, so we have to use acoustic survey methods instead of optical. That adds the level of abstraction and interpretation familiar to any land archaeologist who uses remote sensing technologies like resistivity, conductivity, or ground-penetrating radar.
How does artifact preservation differ in a waterlogged environment than on dry land? Are certain materials more likely to survive?
Some materials are certainly more likely to be preserved underwater than on land. The example I always use is fabulous bronze artwork from the classical world. Bronze survives quite well underwater because it oxidizes and decays so slowly in that environment, but also because it is out of sight and out of reach. On land, it was easy for people to convert ancient bronze into a new form as time passed: classical statues to Byzantine swords, swords to medieval church bells, bells to early modern cannon.
The ceramic artifacts we encounter on deep-water wrecks are typically better preserved than we see in most other contexts. Wrecking is a violent process, particularly when the ship strikes a reef or the shoreline. But when vessels transiting the open sea are overcome by fire, wind, or waves, the process is less destructive than it would be in shallow water. Once they hull slips beneath the surface, hydrodynamics right the ship as it falls to the sea floor. All of the ancient deep water wrecks I’ve seen landed on their keels, with cargo mostly contained in the hull and largely intact. As the organics like the hull, decks, and masts are consumed by sea creatures, the inorganic cargo is laid open to inspection. The end result is a clear view of mostly complete transport jars (amphoras) and other items.
Prasonissi view
Another example of good preservation is ancient DNA. We’ve recently developed a technique to extract ancient DNA from coarse ceramic artifacts, including amphoras. Amphoras are the most commonly encountered type of artifacts on ancient Mediterranean shipwrecks. They were used to transport all sorts of liquid and semi-liquid goods from the fifteenth century B.C. through the Middle Ages. Because the jars were dry when contents were originally added, the ceramic walls of the amphoras soaked up some of the stuff put in them. Once soaked into the ceramic matrix, the DNA was captured. The sun’s ultraviolet light cannot penetrate through the water to degrade DNA on shipwreck artifacts. Even after thousands of years underwater, the DNA persists in the ceramic. On land u/v light would probably have destroyed the DNA.
You have mentioned that deep-sea trawling is incredibly detrimental to underwater sites, and can sometimes completely destroy them. Are any steps being taken to resolve this issue with fishermen?
This is an issue that is completely overlooked by the government regulatory agencies world-wide. There seems to be no recognition that some commercial fishing practices damage or destroy underwater cultural heritage. No steps are being taken to mitigate this damage; in fact, an increase in fishing effort is actively encouraged to more fully exploit some species, and at greater depths. Archaeologists often criticize treasure salvors and sport divers for harming shipwrecks, but the truth is that their activities represent a tiny fraction of the total harm done to wrecks. Huge factory trawlers are literally scraping the sea floor clean in some areas. Any ancient shipwrecks that lie in their way are obliterated. I’ve seen the result of this in several places throughout the Mediterranean Sea, and at depths down to 800 m. In some places, the sea floor looks like a field at sowing season: long furrows in the mud, with everything else plowed under or carried away.
On past projects you have often utilized autonomous underwater vehicles (AUVs) to map and photograph wrecks that are too deep for scuba divers to reach. Can these robots also be used to excavate deep water sites, or is excavation still a job best left to humans?
So far Autonomous Underwater Vehicles are not capable of excavation, but they are very efficient at mapping sites. However, other types of underwater vehicles can be used for excavation at great depth. Human Occupied Vehicles and Remotely Operated Vehicles equipped with manipulator arms and water jets and suction pumps can be quite effective at excavation, but there must be a skilled person operating the controls. I can easily envision a day in the not-too-distant future when we’ll discover deep water shipwrecks of such great significance that we must investigate them via excavation.
The Project Phaedra 2006 website states that one project goal was “to document statistically significant numbers of ancient shipwrecks from various periods in order to reach new insights about human history and pre-history.” Have any interesting statistics appeared as to date? Were there any types of ships/voyages that seem to have ended in wrecks more than others?
We’re still in the preliminary phases of our broad-area survey in the Mediterranean region. However, some tantalizing numbers are beginning to emerge. In 2008, I worked with the Hellenic Ministry of Culture around Chios again. We surveyed ten ancient shipwrecks in ten days. Most of the sites were Late Roman/Early Byzantine, and the wrecks appeared to be smaller than the Classical and Roman sites we’ve seen elsewhere. We wondered if the wrecks indicated s shift in trade patterns in the fourth and fifth centuries A.D., as the Roman Empire dissolved and some of its capital went away. Perhaps smaller ships were used by traders, and they sailed along different routes. But we won’t know with any statistical probability until we study a much greater sample.
You’ve been working around the Greek Island of Chios since 2005. Have there been any changes in your methodology or approach to the project over the past three years?
My Greek colleagues and I very consciously have been advancing methods for underwater archaeology. We started with Autonomous Underwater Vehicles for the survey of the fourth-century B.C. wreck near Langada in 2005. AUVs had never been used before for archaeology, and we had a suite of new sensors that likewise had never or only rarely been applied to archaeology. We mapped the wreck with multi-beam sonar, imaged and photo-mosaicked it with a high-resolution digital camera, collected chemical data over the site to measure dissolved organic matter, aromatic hydrocarbons, and chlorophyll. In 2006 we deployed an in situ mass spectrometer over sea floor features and shipwrecks, to map their chemical signatures. We also collected down-looking video imagery over shipwrecks and used still frames from the video to produce photo-mosaics of the sites. Most of the 2006 work was performed from a Human Occupied Vehicle, Thetis, operated by the Hellenic Centre for Marine Research. In 2007 we further developed our technique for identifying shipwreck cargoes from ancient DNA trapped in the amphoras. In 2008, we took some of our deep water techniques for rapid photographic survey and tried them using a high-resolution camera deployed by scuba divers around Chios. The end result of all of this work is a comprehensive approach to rapid underwater survey from the shoreline to the deepest abyss, using a variety of vehicles and sensors. In the future we intend to deploy AUVs from shore, eliminating the need for an expensive research vessel. We’ll ping-pong the robot between points of land, maybe between Chios and Lesbos, to detect any shipwrecks in the deep open water there.
Your work with Maria Hansson has revealed that DNA fragment analyses can tell us what ancient ceramic vessels once contained. Are there any limitations you are finding in this new technique? Could it potentially be used at any site where ceramics are discovered?
Our DNA investigations are perhaps the single most exciting development in our research portfolio. The conventional wisdom had been that the marine environment would destroy DNA. We proved that incorrect in our pilot project with the amphoras from the fourth-century B.C. wreck at Chios. In 2007 Maria Hansson and I went back to Athens to work with Dimitris Kourkoumelis, Theotokis Theodoulou, and director of the Ephorate of Underwater Antiquities Calliopi Preka-Alexandri. We collected DNA samples from nine more Classical amphoras, recovered from various depths over the past 40 years. Our initial findings indicate that ancient DNA preservation is far more robust than we dared hope. It may be the case that all coarse-ware ceramic artifacts contain ancient DNA in their matrices, so long as they were filled with liquid or semi-liquid contents.
There are some limitations to the DNA technique, however. So far we have only tested unglazed ceramic artifacts. Glazed ceramics or glass probably won’t capture any DNA because they are not porous. We also have limited our investigations to ancient DNA of land plants, and have targeted chloroplast markers specifically. We don’t know if we’ll ever be able to differentiate marine plants and animals in the amphoras, because of the obvious problem of post-deposition contamination. Likewise, we aren’t sure if we can overcome the two major problems of DNA investigations of artifacts from land sites: contamination and DNA destruction from ultraviolet light. We have plans to pursue those questions in the near future, pending funding.
Has the DNA analysis revealed any information about Chios that would be otherwise unattainable?
So far our sample size is too small to reach any definite conclusions. However, our investigations of the fourth-century B.C. wreck amphoras indicates that the well-known fourth-century Chian straight-necked amphora was not a wine jar exclusively. Some scholars have suggested that wine was not the only product carried in these jars, but our results are the first definitive proof that first-use Chian amphoras of this style sometimes carried olive products. As we analyze more amphoras from Chios, we will be able to draw a far more accurate picture of the nature of Chian agriculture production, food preparation and preservation, and export trade.
What are some other projects you have worked on outside of the Aegean?
I’ve worked on surveys of an American Revolutionary War privateer off the coast of Maine; excavations of seventeenth- and eighteenth-century colonial vessels in New Hampshire; investigations of a Royal Navy man-o-war wrecked on the Needles, Isle of Wight; surveys of eighteenth- and nineteenth-century merchant sailing vessels in the Stockholm archipelago in Sweden; shipwreck surveys off the Turkish Black Sea coast; and the Skerki Bank deep-water archaeology projects in international waters between Sicily and Tunisia. And every once in a while I take contract work to survey features in lakes and rivers around New England.
What is the strangest artifact you have ever uncovered from a wreck?
I once found a loaded nineteenth-century pistol in a New England river, and in a New England lake I found a safe that apparently was stolen during a robbery and thrown off a bridge. Both of those finds raised some interesting questions, but neither was associated with a shipwreck. On wreck Skerki F we found rough-cut stone blocks and column blanks, at a depth of 850 m in the Mediterranean. So far, though, we’ve mostly encountered the mundane stuff of everyday life and trade in the ancient world. That’s a good thing–the ordinary material gives us the true view of the past, while the oddities are aberrations that can confuse the picture.
