Understandably, there is often a focus on maritime archaeological sites that lie underwater and many of the most impressive or important ones, like the Mary Rose, or the Vasa are discussed during the shipwrecks course. We are also familiar with sites on land that have their origins in maritime worlds, ship burials like Sutton Hoo, or silted up harbour sites such as Myos Hormos in Egypt. In between these two zones, one on the land, and one underwater, lies the narrow strip of the intertidal zone, which contains an equally amazing array of archaeological remains. These finds include globally significant sites such as the Bronze Age boats at Ferriby on the River Humber, records of everyday activity such as fishtraps, the footprints of walkers from past millennia, or Victorian piers.
The ever-changing nature of the inter-tidal zone means that is presents its own unique set of challenges as a working environment. This is especially true in countries such as the UK where there is a very large tidal range. The extent of the inter-tidal zone is increased, but the time-window during which archaeological remains are accessible can be very limited. The nature of the inter-tidal zone around the UK is also very mixed, ranging from vast expanses of hard sand, to estuarine silts and mud. Working on sites in the latter is like working in a vat of treacle or thick syrup, but with a much worse taste and an enduring smell that clings to you long after you have left the site!
Accessing sites in these areas can be fraught with difficulty and real danger of literally becoming stuck in the mud in the face of a rapidly incoming tide. Knowledge of the local conditions is therefore of critical important, as is a pair of tight fitting wellies, or even a dry suit. Reaching a site might involve a significant walk, carrying all equipment, although options to make life easier include hovercraft or even arrival by boat on estuarine islands. Developing technology using drones for remote surveys and photographic recording is also making life much easier.
Finally, when the site is reached, its location within the tidal regime might dictate that work is limited to a very short window, perhaps 45 minutes if located near to the low water mark. I was lucky enough to work on a newly exposed site on the East Winner sandbank, Hampshire, which was a well preserved 19th century shipwreck, but where we could only access the site for one hour, every two weeks, not at all convenient. On other sites that are situated closer to the high tide line work can carry on for hours. The location of the site in the tide can also mean that access is only available every few weeks at the lowest tides, which can be a further impediment to regular work.
Given all of these problems, the question might be asked as to why we bother to work in such an area. The answer is simple – because the archaeological remains that are contained there are often fantastically preserved by mud, silt and sand. By extension, they are often remains that have never been recorded before (because of being covered) and so offer new information to add to our overall record. At a more visual level, such sites can be incredibly evocative as they emerge from the receding waters, and exist in our world for a limited period of time before they are reclaimed by the incoming tide. This constantly changing physical context offers the final reason for working in the intertidal zone – that many of the sites that are found, are under immediate threat when they appear, from sediment erosion or being swept away by the sea.
The importance of archaeological remains in the intertidal zone is being increasingly recognised within the UK. The nature of the sites means that it is often possible to visit them in person, or to volunteer to help with the survey and recording of them. Much of this work takes place in a very reactive way, because sites are often uncovered and exposed without warning, and so work cannot be planned in advance. So if you are interested in learning more about intertidal archaeology please visit the websites of the Maritime Archaeology Trust, or the CITiZAN Project.
You may also be interested in What are the environments that maritime archaeologists work in? which is a step in Week 1 of Shipwrecks and Submerged Worlds: Maritime Archaeology.