You will know by now that one of the challenges that we have faced in trying to learn about the layout and development of Portus has been a methodological one. What kind of strategy should one use to extract the maximum amount of information in as short a time scale as possible, without causing damage to the buried archaeological remains?
We have opted for one that combines different techniques, since each of these tells us something different about the port. Thus we have used geophysics to learn about the extent of the site and the spatial relationships of the large features like canals, basins and big warehouses to one another – an approach that was particular helpful in the flat area between the hexagonal basin and the Tiber, where we discovered all sorts of new structures that made us re-think our understanding of the hinterland of the port.
The canal system is best appreciated on the map of this period, linked and also shown on a zoomed map below. Look out for the Trajanic Canal (what I called the “transhipment canal” or Canale Romana
), the northern canal and the southern canal. We have also been doing this in the Isola Sacra
to the south of Portus, locating a massive new canal, and very recently even finding out that the neighbouring river port of Ostia was substantially bigger than had been generally understood.
In many cases we have been able to provide complementary information about the character and chronology of some of these new buildings by collecting archaeological material lying on the surface of them, a technique known as surface sherding. However, there is a limit to what this kind of approach can teach us about individual buildings such as the Palazzo Imperiale
and the navalia, and in order to find out more about their layout, function, decoration and development, we have used open-area excavation, using the geophysical results as our guide when thinking about where best to excavate.
Naturally, of course, any excavation is preceded by a careful topographical survey of the ground surface and scanning of standing buildings to provide further clues and then conducting the excavation within an entirely digital recording strategy. Since, therefore, all of our survey and excavation is “born digital” it becomes possible to draw it altogether to create 3D reconstructions of standing buildings. That, however, is another story.
Hypothesised canals identified via geophysics at Portus – Maria Del-Carmen Moreno Escobar © University of Southampton
Simon also mentioned two technical terms – surface sherding and topographic survey. Topographic survey refers to mapping the shape of the land, which can indicate buried structures. Surface sherding is the process of walking across ploughed fields and recording the archaeological material (in this case sherds of pottery). The distribution of these sherds frequently gives us an insight into the buildings that lie beneath, and the activities that took place in the past.
Next you will hear from Kristian Strutt in a step discussing the wider landscape, and then you will learn about geophysical techniques. We combine these with other methods to get a picture of how the site of Portus was arranged, and also what areas to concentrate our excavations on.