Roman Shipwreck & Amphorae Cargo: An Undersea Archaeological Survey

This segment covers the conservation process for waterlogged wood artifacts and the ethical dimensions of maritime archaeology. The wood is very soft, like sponge, because it is waterlogged. Waterlogged wood is just so delicate. To preserve it, it must be very slowly desalinated in fresh water, and then the water content will be replaced with a chemical called PEG (Polyethylene glycol). This is a waxy substance that will replace water in the wood so the wood doesn't become twisted as it dries, preserving the structure and shape of the artifact. The segment explains how the Greek pottery shards were identified, noting that with great difficulty in some cases because they were either washed into small pebbles like this by the action of the sea or turned into solidified lumps of concretion like these. Among all this junk, there were a number of shards that were recognizable from the engravings of the vases that have been produced in Italy when Sir William was there in the 1790s. These images served the conservators who worked so hard on the reconstruction of many of the vases that were on the Colossus as patterns. This is like a jigsaw puzzle, except with a jigsaw puzzle you expect all the pieces to be there otherwise you ask for your money back. The segment also explores the commercial and ethical dimensions of maritime archaeology, noting that in the 1970s when Roland Morris excavated the bow section of the Colossus, he brought up far more than Greek pottery. Hundreds of artifacts found their way into his maritime museum. Since his death, the museum's been closed and the exhibits are being auctioned. There is obviously a thriving collector's market for all things nautical, with items like screws being sold at auction for significant sums. The segment explains that these screws are made of a kind of copper alloy which means they were used below the water line of the ship. They are mass-produced but each one is almost individually crafted. This was modern technology for the time and would have impressed people. The segment also discusses the ethical implications of collecting antiquities, noting that William Hamilton's activities in acquiring archaeological material generated the need for more archaeological material and generated more collectors as he expanded his collection. This has happened in the past where material has been recovered and has been sold on the black market. The more material comes up, the more that goes on the market, the more it generates a market, therefore more material is required. What we would like is to slow that down and have archaeological material treated in a disciplined and sensible way so that the material is recovered and the information is not lost forever.

Waterlogged archaeological wood requires specialized conservation because water molecules occupy the cellular structure and provide mechanical support; when excavated, allowing the wood to dry normally causes water evaporation that pulls on the cellular structure, resulting in irreversible dimensional changes like warping and cracking. The conservation process involves immersing the wood in polyethylene glycol solution to replace water within the cellular structure, then freezing the wood to convert remaining water to ice, and finally using a freeze dryer under vacuum to remove the ice through sublimation (direct transition from solid to gas), thereby preserving the wood's original dimensions without damage.

In underwater archaeology, waterlogged wood artifacts require specialized conservation techniques including tent systems with atomized irrigation to prevent drying, which causes irreversible damage; conservationists assess each artifact's unique condition (wood type, fastener material, deterioration level) and apply individualized treatment methods, using wooden supports, epoxy materials, and aluminum foil barriers to provide structural support while avoiding direct contact with the artifact.

Archaeological wood after centuries underwater has lost all cellulose originally holding its structure, now only water retains its shape. Organic materials are preserved because they are saturated with water. If removed from water, they suffer irreversible degradation. The desalinization process involves submerging pieces in freshwater tanks where conservators monitor salt concentration through regular checks. The accumulated salt over many years dissolves slowly, preventing further deterioration of the organic materials.

Recovered artifacts require specialized conservation treatment to prevent deterioration. All artifacts are stored in wet tanks immediately after recovery. Electrochemical treatment using special chemicals and electric current removes salt molecules that would cause iron artifacts to crumble when exposed to air. Large objects like cannons may require five to six years of treatment. Before conservation begins, X-rays reveal what lies inside concretions. Conservators then use air scribes to carefully remove marine growth. This multi-stage process transforms amorphous concretions into identifiable artifacts suitable for museum display.

The exact contents of each amphora were meticulously documented by Roman customs officials and merchants. For this, they invented the tituli picti, an early form of modern barcodes or labels. Directly on the neck or belly of the amphora, detailed information was painted in red or black ink. This labeling contained precise information: the exact weight of the empty and filled vessel, the name of the merchant, the country of origin or the plantation, the exact year of harvest using the names of the reigning consuls, and often a quality guarantee from the responsible controller. Through this system, a buyer in the Roman market could immediately recognize whether the olive oil in the amphora came from Andalusia or was inferior oil from another region.

This lecture examines the wine production and trade of Roman Narbonaise (modern southern France) through painted inscriptions on amphorae (tituli picti) and barrel graffiti. The corpus of 155 inscriptions reveals that Narbonaise produced several wine types: aminéum (the most frequent noble grape variety, imported from Greece), picatou (resinated wine for preservation), mulsom (honeyed wine), and passum (sweet wine from sun-dried grapes). The wines were predominantly white, with quality wines often millésimé (dated). Three main geographic origins are identified: Béziers (producing Bassé tincé), Marseille (Massaliot wine, the oldest cultivated in Narbonaise since the 6th century BC), and Vienne (producing the premium 'poissé' wine). Wine was exported to Rome, Arles, and the German limes, with quality wines transported in both amphorae and barrels.

The Betic cartel used a sophisticated system called 'tituli' to track every amphora. Each jar was painted with complete information including origin, weight, merchant details, and inspector approval. This created a fraud-proof traceability system that gave them total control over the supply chain, functioning like modern barcodes but with ancient technology.

This section examines how amphora contents were identified and documented in Roman trade, exploring broader implications for understanding Roman economic and cultural systems. Papyrological evidence demonstrates Romans recognized various amphora types by specific names and associated them with particular contents, as noted by Pliny the Elder regarding Talamein wine packaged in laguna amphoras being passed off as superior Mamertenum wine. Titulus pictus labels were generally applied to sealed amphoras, with Pompeii research showing very high percentages bore such labels. When amphoras were refilled, removing prime-use labels became necessary to avoid confusion, though known cases show conflicting labels on single vessels. Documentary evidence like Tabulae curatae (e.g., TP Salt 80 from Pompeii's Oscan archive, AD 261) documents amphora consignments specifying content and quantity. The main ports and secondary ports theory helps explain amphora circulation patterns, with some containers circulating between major ports while others moved between main and secondary ports. Economic motivations included avoiding costs of new amphoras, utilizing containers in regions lacking local production, and potentially using amphoras as currency or collateral. The section emphasizes that context remains fundamental to archaeological interpretation, with shipwrecks providing stronger evidence for Type A reuse than terrestrial sites, and that integrated analysis combining archaeological, documentary, and residue evidence provides the most reliable picture of amphora reuse practices.

Monte Testaccio preserves thousands of amphora inscriptions that provide unique economic documentation. These markings include net weight, gross weight of contents, seller names, and origin stamps. No other archaeological site offers such comprehensive records of ancient commerce. Over 260 years, approximately 53 million amphorae were deposited here, creating an unparalleled archive of Roman trade, distribution networks, and market economics that continues to inform our understanding of ancient economies.

Underwater photogrammetry enables 3D reconstruction of submerged objects by using specialized equipment like spherical diving masks to minimize refraction errors, combined with target-based calibration systems and bundle adjustment algorithms to achieve centimeter-level accuracy, as demonstrated in the Costa Concordia shipwreck survey where researchers successfully mapped a 60m x 10m damaged hull section that was partially submerged and partially emerged.

Photogrammetry is a technique that uses photographs to measure and create 3D models of objects. The Titanic was scanned using remotely controlled submersibles that traveled the length and breadth of the wreck, capturing 700,000 images from every angle. These images were then processed to build an exact 3D reconstruction, demonstrating how photogrammetry can create highly detailed digital models of underwater archaeological sites.

Non-invasive photogrammetry allows scientists to construct highly accurate three-dimensional digital twins of wreckage without physical contact. The remotely operated vehicle executes structured geometric flight paths along the hull, capturing thousands of overlapping high-resolution images. Software reconstructs geometry from subtle shifts between frames, yielding accurate measurements of deformation and damage down to centimeter scale. However, this technique is limited by physical line of sight—cameras cannot penetrate heavy marine growth or see through collapsed steel folds. Since legal non-disturbance protocols are absolute, robotic vehicles are forbidden from moving fallen debris. By meticulously recording the trajectory of inverted structural beams, teams can mathematically trace blast pressure back to its exact point of origin within the gutted hanger space.

Modern underwater archaeology uses photogrammetry and laser scanning technology to create precise 3D digital models of shipwrecks, allowing researchers to study and document submerged artifacts without physically disturbing their original context, as demonstrated by the documentation of a Roman merchant ship carrying amphorae of Garum (fermented fish sauce) in the Ionian Sea.

Photogrammetry revolutionizes underwater archaeology by enabling the creation of precise 3D models from thousands of overlapping photographs. The process involves capturing 20-10,000 images with 50-80% overlap from multiple angles, then using software to generate detailed 3D reconstructions. This technology overcomes the limitations of traditional diving by revealing shipwrecks in their entirety, enabling virtual exploration for non-divers, facilitating archaeological study of degradation patterns, and allowing production of exact 3D printed replicas. Successful implementation requires careful planning, advanced diving equipment including rebreathers and trimix, and typically involves multiple dives with safety divers accompanying the team.