Protecting Underwater Cultural Heritage
Archaeological sites lying in rivers, lakes or ocean beds provide an enormous wealth of information on the life of our ancestors. Unfortunately, treasure hunting is a very lucrative activity and thousands of treasure hunters pillage shipwrecks to sell their contents. To protect this cultural heritage, UNESCO adopted in November 2001 a Convention that aims to prohibit underwater excavations conducted for purely commercial ends.
Since Antiquity, people have crossed rivers, lakes and oceans to conquer other lands, establish trading routes or simply search for adventure and fortune. In this to and fro, hundreds of merchant ships loaded with cargoes of porcelain and amphorae, galleons carrying jewels or warships with artillery were shipwrecked or attacked by enemy fire, both along coastlines and in high seas.
Water has the virtue of preserving goods for thousands of years, keeping them in far better condition than if they had been buried under land. With the development of underwater archaeology, these remains can now be studied. Every ship lying at the bottom of the sea tells us about naval construction techniques, war strategies, craftsmanship or trade routes * no vestige on land can render such information (see previous article).
There are still more than three million undiscovered shipwrecks scattered across the world's oceans, according to experts. In North America alone, one database contains 65,000 ship loss records from 1500 AD to the present. Some 850 ships have gone to the bottom of the seas surrounding the Azores since 1522. At least 90 percent of them were Spanish galleons and another 40 were Portuguese vessels on the way to India. In the bay of Montevideo (Uruguay), for example, more than 200 important shipwrecks were registered between 1722 and 1930. These included frigates, corvettes, passenger ships, steam and sailing vessels. The Philippines, another historic stopover for the Spanish, was an important maritime trade link with Southeast Asia for more than 1,000 years.
Ships aren't the only treasures lying on the ocean floor. Cyclones and earthquakes have buried entire cities. In Jamaica, the trading town of Port Royal disappeared beneath the waves after an earthquake in 1692. The remnants of ancient civilisations such as the Lighthouse of Alexandria in Egypt and the Neolithic villages under the Black Sea are other examples. In the Yucatan region of Mexico, flooded natural cavities and sacred wells hide precious information on Mayan culture and civilisation.
Unfortunately, most of these treasures are under serious threat. Virtually everybody today can access the ocean depths. An amateur diver with a simple aqualung can easily reach any number of wrecks, many of which are located in shallow waters, and remove objects. Then there are the professional "treasure hunters", well-financed and equipped with state-of-the-art technology that allows them to plumb the deepest seas. These modern pirates scour the ocean floor in search of fabulous "lost" cargoes that can be sold for incredible sums, and which then become "lost" again to the world's private collectors, never able to be studied, understood, explained or shared with the public (see Treasure Hunters)
An international agreement, at last
In an attempt to stop this practice, UNESCO adopted the Convention on the Protection of the Underwater Cultural Heritage in November 2001. It is an international agreement that aims to preserve all traces of human existence which have been underwater for at least 100 years. To do so, the Convention bans excavations carried out for exclusive commercial ends. All countries that sign the Convention must outlaw the activity of treasure hunters through appropriate legislation. The Convention also binds States to prevent the entry into their territory, the dealing in, or the possession of, underwater cultural heritage illicitly exported and/or recovered.
The Convention recommends the preservation in situ of underwater heritage. This important recommendation means that countries should give priority to preserving underwater remnants where they are found and only extract them for the sake of study (see in situ conservation).
Archaeological excavations are very expensive and many countries simply can't afford to protect their heritage. The Convention favours co-operation between countries for training in underwater archaeology, technology transfer and sharing preservation techniques.
"Most countries agree with the norms and principles of the Convention and judge the instrument necessary," says Edouard Planche of the International Standards Section of UNESCO's Division of Cultural Heritage. "All they have to do now is to ratify the Convention as quickly as possible so that it can come into force."
Note : for full text of the Convention, click here
The website of Underwater Archaeology at the National Institute of Anthropology
(Mexico) is very interesting and can be consulted both in English and Spanish:
"Archaeological work is like a book in which the pages disappear as you read
them." Marc-André Bernier, "The archaeologist with frog's legs"
Amphorae are two-handled clay jars. Their shape varies according to their place of origin, age and contents: some have an oval body, others are round or elongated, tapering to a point at the base. In Antiquity, these jars were prized containers for transporting wine, oils, spices and other precious goods across the seas. They tell us that Greeks and Romans appreciated their wine, that a fish-based sauce was a staple of Roman cooking, and that Gallic wine travelled all the way to India. In short, amphorae allow us to imagine the scents and flavours of Antiquity! Those found in shipwrecks off the coasts of the Mediterranean Sea provide us with a wealth of fascinating information on the history of maritime trade in Antiquity. All this, thanks to underwater archaeology!
Both on land and underwater, archaeology is the study and preservation of traces left by our ancestors in order to understand their lifestyles and cultures. Documents kept in archives are a precious resource for archaeologists. But in the case of maritime archaeology, objects are buried underwater. This makes the archaeologist's task both easier and more difficult. Easier because artefacts lying underwater are in a better state of conservation than those found on dry land. It is as if time stops when a ship sinks or an earthquake engulfs a city. A shipwreck is like a photograph of the past revealing aspects of history that land-based archaeology cannot render. But maritime archaeology is also more perilous, because the aquatic environment is not our natural habitat. To explore underwater, archaeologists resort to diving.
An adventurer's life!
Underwater archaeologists don't spend their life locked up in dusty offices under stacks of books * the image we sometimes have of researchers. They are adventurers with a dangerous job! Archaeologists have to dive, contend with fickle weather patterns and pay attention to elements like visibility, ocean currents, water temperature or the depth of a wreck. Because of this, they work in special teams and must respect very strict rules. The deeper the wreck, the less time they can spend underwater. Usually, archaeologists spend at most two hours a day excavating*one in the morning, one in the afternoon. They know that breaking these rules spells danger. Teams always include a person in charge of safety, usually an experienced diver. The development of underwater archaeology is closely linked to the invention of new diving equipment. The first underwater excavations date to the invention of the autonomous diving suit, made famous by Commander Jacques-Yves Cousteau in the 1950s.
Down we go !
Today, new diving technologies allow us to excavate shipwrecks beyond depths of sixty metres (180 feet). When this is the case, straightforward diving is too dangerous. Instead, archaeologists descend in small submersibles that can carry two people along with equipment to record artefacts (video cameras, regular cameras, computers, robotic arms to extract objects and carry them up to the surface, etc.). These small submarines can travel as deep as 1,100 metres (3,300 feet). Wrecks found at such depths offer one great advantage: they are often in a much better state of conservation than those closer to the surface. The deeper the wreck, the less oxygen and sunlight reach it. Ocean currents also cause less harm to wrecks at such great depths. Nonetheless, most wrecks are found closer to the surface, near coastlines.
Whether excavating underwater or on land, archaeologists employ the same techniques. An archaeological site is usually covered by sand or earth. The first job is to carefully remove this cover, layer by layer. Most important, archaeologists must record every gesture they make. For this, they may do drawings or take photographs. Digital photography is increasingly favoured today because much sharper images are obtained after computer touch-ups. Archaeology is a time-consuming, painstaking and meticulous task. Several years can go by between an excavation and the publication of findings.
Finally, archaeologists must never forget that the pieces they study also belong to our heritage. As such, these vestiges of the past have to be preserved, even if the task is difficult. "When you excavate, you necessarily upset the site," says French archaeologist Eric Rieth. "But we have to try to preserve it in such a way that within 50 years, someone can still return to study in the same spot."
Tapping many talents
Underwater archaeology turns to other fields of study to conduct research. For example, to locate a wreck and draw marine maps, geographers specialised in the relief of ocean beds are consulted. To preserve excavated artefacts, the excavation team must include people skilled in conservation techniques. To record objects, underwater photographers or graphic artists are required. When animal bone remains are found, they are sent to an archaeologist specialised in zoology. The science of dendochronology allows us to date wrecks with great precision. For instance, it can tell us the age at which a tree was cut down or its geographic origin.
What happens during an underwater excavation?
To study the remnants of a ship, archaeologists must first spell out their research agenda. For example, they may be interested in knowing when a ship was built, the type of wood used, the shape of the hull or learn more about naval construction techniques. Then a precise excavation plan is drawn up, explaining how long it will take, the number of people involved and their respective duties. The excavation team usually includes a chief archaeologist, fellow archaeologists and students, professional divers, curators and photographers. Without forgetting the ship's crew without whom the operation could not even begin!
Equipment required for the excavation is stored on board: water vacuums, GPS instruments for locating the wreck, a metal grid, cameras, computers, slates, baskets for transporting objects, a crane and more. Once the material is revised, it's time for a wonderful journey to begin!
A real jigsaw
Underwater excavation takes place in several stages (photos of each stage by DRASSM, France).
1. First, the archaeological site has to be cleaned. For this, archaeologists use powerful underwater vacuums that function with a pump installed above water.
2. Surveying the site. Like in land-based archaeology, underwater excavation requires the installation of a metal grid divided into square frames of one, two or four metres (three, six or twelve feet). This tool is essential for recording all objects found. Archaeologists must number every single piece according to its position on the grid.
3. Observation and record. Archaeologists usually excavate in teams of two. While observing the wreck, their have to draw and take photographs of the pieces they see, and record where they fit onto the grid. In short they reconstitute the wreck frame by frame, noting down their observations. Archaeologists love these kinds of jigsaws! To execute their drawings, they use PVC slates by which they can communicate with each other underwater.
4. Extracting pieces. If archaeologists decide to bring some pieces up to the surface for study, they use heavy net baskets designed for ensuring the safety of objects. These are carried to the surface through inflatable balloons with a carrying capacity of 30 to 2,000 liters. On the spot, a curator performs a first protective treatment of the pieces before they are transported to a special laboratory.
5. Resanding. To protect the wreck from naturally-occurring damage and pillaging, it is important to resand the site after each excavation.
A game idea
Take a photograph of an archaeological piece. Divide it into frames. To play the game:
a. cut each frame
b. reproduce the image of each one on scale paper.
c. join the frames...
d. you've reconstituted the piece!
New technologies have opened the way for all - from amateur diver to local fisherman - to reach wrecks in shallow waters and remove objects. Thousands of people do it - most of them probably unaware that they are forever disturbing a unique archaeological site to decorate their mantelpiece or garden. Canadian archaeologist Robert Grenier, who is also the director of the International Scientific Committee for Underwater Cultural Heritage for ICOMOS (the International Council of Monuments and Sites), insists on the urgency to make divers aware of the importance of the situation. " We need divers to collaborate with us to preserve and protect wrecks," he says.
The real modern-day pirates though are the professional organizations with sophisticated diving teams and equipment, who're out to make a profit. These people scour the oceans for wrecks that went to the bottom with fabulous cargoes, often worth tens of millions of dollars when offered for sale privately or through the world's prestigious auction houses.
The australian treasure hunter Michael Hatcher, for example, earned nearly $15 million by dispersing a collection of Chinese porcelain found in the Geldermalsen, a Dutch ship that disappeared in 1752 in the South China Sea. The sale was organized by Christie's, one of the world's top auction houses. The same happened with the Spanish galleon Our Lady of Atocha, which sank in 1622 off the Florida Keys (United States). In 1985, the American Mel Fisher extracted a cargo of gold, silver and jewellery worth an estimated $400 million. Result : the archaeological artefacts were dispersed around the world into the hands of private collectors, without ever being studied.
The American Bob Marx spent over 45 years of his life surfing the oceans in search of wrecks of Spanish galleons travelling between the Old and New World. "I've discovered more ships and pulled up more treasures than anyone in the world," he boasted a few years ago. In 1957, he was arrested by Mexican police as he was recovering thousands of objects from a wreck known as El Matancero, in the Yucatan peninsula. Shocking archaeologists the world over, he reportedly used hammers, scissors and explosives to excavate. He now claims to be heritage-conscious and to use more sophisticated, site-friendly techniques.
Bob Marx has worked in 62 countries, often as a consultant to governments. "Usually, I work on the basis of a 75 percent cut for myself and 25 percent for the State," he said in 1997. Indeed, one of the most pressing problems for underwater heritage protection is that treasure hunting is often conducted legally. Archaeological operations are so expensive that many countries prefer to sign deals with treasure hunters in order to recover part of their heritage.
Worlds apart: treasure hunters and archaeologists
Is it possible to work with treasure hunters to conduct underwater excavations that respect all scientific norms ? No, say archaeologists. Any attempt is doomed to failure. Our logic, they argue, is completely different.
Archaeologist: the treasure lies in the knowledge revealed by an object.
Treasure hunter: the treasure is the money that can be earned from selling an artefact.
Archaeologist: proceeds scientifically, slowly and with great care for conservation.
Treasure hunter: speed is the rule and conservation is not a priority.
Archaeologist: findings can benefit entire communities.
Treasure hunter: findings are assessed in economic terms and benefit very few people.
Archaeologist: contributes to improving our knowledge of the history of humanity.
Treasure hunter: destroys traces of our past.
Protection of the underwater cultural heritage
One of the biggest problems to protect underwater archaeology is the fact that very few countries have specific laws in this area. Complicating matters, the few existing laws vary greatly from one country to another. This is why UNESCO decided to develop an international legal instrument in this field. This instrument is designed to encourage States to develop their own laws respecting some important principles: in situ preservation, the prohibition of purely commercial excavations, and careful attention to only use exploratory methods and techniques that don't harm the wreck.
There is often an international dimension to the various pieces and goods of underwater archaeology because of the diverse origins of the boats and their cargos. Imagine the case of a Spanish galleon that sunk in the territorial waters of a Caribbean country. Who should set the conditions for excavating this wreck?
These kind of national decisions vary from one country to another. Sometimes a minister is responsible. In other places, it is entrusted to a university or a national institute for archaeology, research or maritime affairs. These very same institutions, which can be private or public, are also responsible for financing the excavations. In France, for example, the Ministry of Culture is responsible for underwater archaeology, oversees the excavations and even finances most of the activities (see box).
Indeed, underwater archaeology is very expensive. In fact, the least developed countries cannot afford to undertake major excavations. They are sometimes obliged to sign agreements with "treasure hunters" to explore their heritage. This is why one of the main goals of the Convention is to promote co-operation between States (Articles 19 and 21): “States Parties shall cooperate in the provision of training in underwater archaeology, in techniques for the conservation of underwater cultural heritage and, on agree terms, in the transfer of technology relating to underwater cultural heritage”.
(Suggestion: write a text on how underwater archaeology is protected in your country. What are the principles, who decides to undertake an excavation and who finances the work?)
A protection model
Since 1961, France has been one of the first countries in the world with specific laws protecting its underwater archaeology. Furthermore, in 1966, the government set up a special unit for this work. The Department for Underwater and Undersea Research, a branch of the Culture Ministry, enforces legislation relative to the discovery and exploitation of shipwrecks with important archaeological, historical or artistic value. "Any object or wreck found underwater must be reported to the office of Maritime Affairs, which transmits the information to us," explains Jean-Luc Massy, director of the Department. "We then conduct an appraisal of the site in order to assess its importance and take all necessary measures for its conservation and study. We also enter its location in a cartographic data base." The Department keeps a daily inventory of archaeological sites classified by theme and period.
"No one can conduct underwater archaeology without our consent," says Massy. On behalf of the ministry, the department gives authorizations to associations, universities and research institutes for all excavations, surveys and prospecting over which it has scientific and technical control. "Methodological quality and professional experience are the main criteria for all those engaged in such activities. What guarantees can the team woorking on the artefacts provide in order to ensure the correct recording of archaeological data, the study of artefacts taken from the wreck, their preservation and restoration? On the other hand, the period of specialization of an archaeologist and the period to which the wreck belongs are determining factors. For example, a specialist in excavations from the 17th and 18th centuries will have difficulty obtaining a permit to excavate a wreck from the Etruscan period. Likewise, an archaeologist who is not a specialist of the Palaeolithic era cannot obtain permission to excavate an underwater cave dating back to the early prehistoric period."
Within the framework of the Department's budget, the Ministry of Culture contributes every year about 910,000 euros for underwater archaeology. In addition to authorizing excavations and ensuring that they are properly conducted, the department conducts its own research programmes. It is responsible for training in underwater excavation, sharing the research results by publishing studies and making collections from the underwater milieu available to museums. The department also receives scientific collaboration from institutions like the National Institute for Scientific Research and financial help from local organizations in undertaking excavations. It does not always finance the excavations it authorizes. It can, however, offer logistics support such as the services of the Archeonaute, a boat specially designed for underwater archaeology. This boat, which belongs to the Minister of Culture, is equipped to handle a scientific team of 11 people.
A man with a passion
Michel L'Hour, a French archaeologist, works for the Department for Underwater and Undersea Research, part of the French Culture Ministry. He has led many underwater excavations on shipwrecks from the 16th, 17th and 18th centuries off western France, in the Atlantic Ocean.
How did you find your vocation for underwater archaeology ?
I'm from Brittany. In my family, the seafaring tradition is passed down from father to son*it actually goes back to my grandfather. When I was a kid, I was fascinated by the sea and its history. I wanted to join these two passions, so I opted for underwater archaeology 25 years ago.
What are some of the most satisfying moments of your career ?
There are many! The latest is perhaps two years ago, during the excavation of La Natière in Saint-Malo, where a rather special looking skeleton was found. I said that it must have belonged to a domestic animal killed during the sinking because I'd found it stuck underneath a case for bottles. We sent it to experts in zoological archaeology who weren't able to identify it at first. In the end, comparing it with other skeletons at the Museum of Natural History in Paris, they found the answer: it was a monkey, a macaque usually found in Gibraltar or North Africa. They calculated that it was less than six months old because some of the tiny bones of the skeleton weren't entirely set.
It was an extraordinary revelation. This data forced us to revise our hypothesis, namely that we were before a wreck dating from 1713. In the account that we'd found in the archives, the captain reported that his ship was returning from a voyage of seven months in New foundland. It's obvious that no monkey could have embarked from this island. And on top of it, it was less than six months old!
Today we are still digging through the archives because we haven't managed to identify this wreck. Other parts of the monkey's body have been found, confirming that it was indeed a domestic animal that had perished in the wreck. Maybe one day we'll stumble upon a document telling us that someone lost a monkey in a maritime disaster, then we'll know which boat it belonged to!
To visit the website of the archaeological study of the French wreck of La Natière
go to: http://lecorsaire.com
In situ conservation
Archaeological remnants can be studied where they are found. This is known as in situ research. They can also be extracted, restored and exhibited to the public in museums. The UNESCO Convention favours in situ conservation as a means for protecting underwater heritage. According to Canadian archaelogist Robert Grenier, "It's been proved that shipwrecks can last thousands of years underwater. Any natural destruction generally occurs well within the first century of immersion. After that, the degradation slows down until the site reaches a stability for centuries."
Archaelogists also agree that the real value of a wreck or an archaeological site lies in studying it as a whole, hence the importance of studying objects in their context. Otherwise, the interpretation loses in value. Sometimes people complain that in situ conservation amounts to prohibiting excavations. Grenier disagrees. "Preserving for the benefit of humanity" means preserving in situ and gaining access to wrecks. Excavations have to be justified and take into account the preservation of the wreck and each of its pieces.
This does not mean that no one has access to sites preserved underwater. On the contrary. The Convention encourages public access to in situ underwater cultural heritage, except when it puts the site in danger. For example, in Nova Scotia (Canada), any diver can visit the Celèbre, a French warship that sank in 1758, on condition they go through a certified agency that organizes environmentally-friendly diving tours.
How to avoid a new shipwreck
On August 10, 1628, thousands of spectators gathered on the beaches of Estocolmo to witness launch of the largest warship ever built, the Wasa. The ship started leaning, quickly filled with water and went down. Thirty of the 150 sailors on board perished. The event was a blow to the powerful Baltic empire of Sweden and its king, Gustavus II. Not only was the ship unable to embark on its bellicose mission but thousands of barrels on board were never recovered. In 1961, more than 300 years later, the Wasa was once again in the public eye. It took thirty years and $25 million dollars to raise and restore the ship. At long last, the Wasa found a new home in a wonderful museum specially designed to house it. Since its opening in 1990, more than nine million people have visited the ship.
The undertaking is impressive, but it's hard to imagine the least developed countries following suit. The conservation of archaeological remains on dry land is very expensive. Is it worth it? "The Wasa is turning to dust," ran newspaper headlines earlier this year, after scientists reported that sulphuric acid formations were gnawing away at the ship's wood. A new treatment would be so expensive that the museum fears it will not have enough funds to save the ship.
Without doubt, conservation techniques must further improve, especially those relating to wood. The shift from an aquatic to a terrestrial environment can entirely disintegrate an archaeological piece. Bloated with water, the wood is harmed when the liquid evaporates. Conserving it entails replacing the water with a liquid that gives the wood more stability. Scientists employ various methods, but none are guaranteed to last forever.
Advocates of in situ conservation argue that new information technologies should be used to reproduce virtual models of shipwrecks. Meanwhile, their best place is on the ocean bed: after all, it took them long enough to adapt to the aquatic milieu, so there's little point in provoking yet another shipwreck.
Journalist for BPI (Office of information for the public)