Excavating the Site

There have been various approaches to excavation over the years as the techniques of archaeology have changed. This is interesting in terms of the development of the subject and we can direct you to further reading if required. However at Villa Magna we will be using the open area excavation technique, the single context system and the Harris matrix will be used for establishing site stratigraphic sequences.

Guide to Stratigraphic Units or Contexts.

The basic unit with which the excavator works is known as the Stratigraphic Unit (called SU at Villa Magna; you frequently see this referred to as a context in English literature and Unita Stratigrafica/US in Italian literature.) It is on this basic component that all site records, stratigraphic relationships and finds distributions are based.

An SU is a discrete archaeological entity. Each SU is basically the result of natural erosion and deposition and the effects of human interaction with these processes. They are often the result of a single action, ie the deposition of a layer of earth, the infilling of a pit or the digging of a hole. SU’s include actions that leave both a positive and a negative record. A positive record is something that has been added to the sequence, such as a wall or floor, or the fill of a pit or post hole. A negative record means that something has been removed from the sequence in order to create it, such as the hole formed by the digging of a pit.

At Villa Magna we also distinguish between SUs (both positive, such as surfaces, layers and dumps, and negative such as pits and cuts), SSUs (Structural Stratigraphic Units) and HRUs (Human Remain Units).

The most crucial element of the actual excavation process is the process of defining SUs and their extents. This can sometimes be very easy, for example a wall or pit may be easy to isolate, whilst an eroded pile of soil may present more difficulties when trying to define the edges. Different archaeologists define SUs differently, and it is usually helpful to consult with supervisors or colleagues if you are uncertain in order to establish consistency throughout the project. To define an SU you need to essentially look for differences, mainly differences in soil textures and colours. At Villa Magna, an SU is the smallest separately identifiable stratigraphic unit that can be recognised on the basis of four main criteria: Colour, Consistency (clayey, silty etc.), Compaction (hard, loose etc.) and Composition.

SSUs, SSUs and HRUs meet at interfaces and it is by recognizing these interfaces that we can start to identify sequences of deposits and establish the stratigraphic sequence of the site The key way to understanding a site’s development through time is through the development of a stratigraphic sequence, this basically consists of considering each SU in chronological order. Within such a sequence the chronologically earliest SU will always be sealed or cut by a later SU. Chronology in this sense refers to the relative date of activity between one context and another. Once a stratigraphic sequence has been established then phasing and dating of elements of the site can take place.

The most important moment in excavation is to establish the relationship between the SU you are investigating and all those in contact with it: is it under or over them? Is it cut by any other feature? Is it the stratigraphically ‘highest’ ie most recent element in your landscape? Once you have made sure of the position and extent of the SU, and it is ‘clean’ and free of any remains of previously excavated SUs it is time to document and record it.