| In today's class I'm going to talk about marine archaeology, |
| the branch of archaeology focusing on human interaction with the sea, lakes and rivers. |
| It's the study of ships, cargoes, shipping facilities, and other physical remains. |
| I'll give you an example, |
| then go on to show how this type of research is being transformed by the use of the latest technology. |
| Atlit-Yam was a village on the coast of the eastern Mediterranean, |
| which seems to have been thriving until around 7,000 BC. |
| The residents kept cattle, caught fish and stored grain. |
| They had wells for fresh water, |
| many of their houses were built around a courtyard and were constructed of stone. |
| The village contained an impressive monument: |
| seven half-tonne stones standing in a semicircle around a spring, |
| that might have been used for ceremonial purposes. |
| Atlit-Yam may have been destroyed swiftly by a tsunami, |
| or climate change may have caused glaciers to melt and sea levels to rise, flooding the village gradually. |
| Whatever the cause, it now lies ten metres below the surface of the Mediterranean, |
| buried under sand at the bottom of the sea. |
| It's been described as the largest and best preserved prehistoric settlement ever found on the seabed. |
| For marine archaeologists, Atlit-Yam is a treasure trove. |
| Research on the buildings, tools and the human remains has revealed how the bustling village once functioned, |
| and even what diseases some of its residents suffered from. |
| But of course this is only one small village, one window into a lost world. |
| For a fuller picture, researchers need more sunken settlements, |
| but the hard part is finding them. |
| Underwater research used to require divers to find shipwrecks or artefacts, |
| but in the second half of the twentieth century, various types of underwater vehicles were developed, |
| some controlled from a ship on the surface, and some of them autonomous, |
| which means they don't need to be operated by a person. |
| Autonomous underwater vehicles, or AUVs, |
| are used in the oil industry, for instance, to create maps of the seabed before rigs and pipelines are installed. |
| To navigate they use sensors, such as compasses and sonar. |
| Until relatively recently they were very expensive, and so heavy that they had to be launched from a large vessel with a winch. |
| But the latest AUVs are much easier to manoeuvre - |
| they can be launched from the shore or a small ship. |
| And they're much cheaper, which makes them more accessible to research teams. |
| They're also very sophisticated. |
| They can communicate with each other and, for example, |
| work out the most efficient way to survey a site, |
| or to find particular objects on the seabed. |
| Field tests show the approach can work. |
| For example, in a trial in 2015, |
| three AUVs searched for wrecks at Marzamemi, off the coast of Sicily. |
| The site is the final resting place of an ancient Roman ship, |
| which sank in the sixth century AD |
| while ferrying prefabricated marble elements for the construction of an early church. |
| The AUVs mapped the area in detail, finding other ships carrying columns of the same material. |
| Creating an internet in the sea for AUVs to communicate is no easy matter. |
| Wifi networks on land use electromagnetic waves, |
| but in water these will only travel a few centimetres. |
| Instead, a more complex mix of technologies is required. |
| For short distances, AUVs can share data using light, |
| while acoustic waves are used to communicate over long distances. |
| But more creative solutions are also being developed, |
| where an AUV working on the seabed offloads data to a second AUV, |
| which then surfaces and beams the data home to the research team using a satellite. |
| There's also a system that enables AUVs to share information from seabed scans, and other data. |
| So if an AUV surveying the seabed finds an intriguing object, |
| it can share the coordinates of the object - that is, its position - |
| with a nearby AUV that carries superior cameras, |
| and arrange for that AUV to make a closer inspection of the object. |
| Marine archaeologists are excited about the huge potential of these AUVs for their discipline. |
| One site where they're going to be deployed is the Gulf of Baratti, off the Italian coast. |
| In 1974, a 2,000-year-old Roman vessel was discovered here, in 18 metres of water. |
| When it sank, it was carrying medical goods, in wooden or tin receptacles. |
| Its cargo gives us insight into the treatments available all those years ago, |
| including tablets that are thought to have been dissolved to form a cleansing liquid for the eyes. |
| Other Roman ships went down nearby, taking their cargoes with them. |
| Some held huge pots made of terracotta. |
| Some were used for transporting cargoes of olive oil, and others held wine. |
| In many cases it's only these containers that remain, |
| while the wooden ships have been buried under silt on the seabed. |
| Another project... |