Depending on the reason for the excavation, a range of people can be involved in deciding on the task to be undertaken.  Landowners, farmers, developers, engineers, architects, local government archaeological planning advisors, ancient monuments inspectors and even television programme-makers are just some of the people who take a role in decision making.  Elaborate development-related ‘rescue’ projects with high costs commonly involve the most decision-makers.

 

Once an excavation begins, day-to-day decisions on the course of the excavation are usually taken by the person in charge (the site director or project manager). The director is also in charge of the overall interpretation of what is being uncovered, preferably having taken into account the opinions of other archaeologists working on the site.  In different parts of the site, area supervisors decide on the order in which features are investigated and how to record them most effectively.  Individual excavators (often known as ‘diggers’) carry out the director’s and supervisors’ instructions – and do most of the hard physical work of excavation.  However, diggers take continual decisions too.  They may not get to decide on the overall strategy of the excavation, but by digging, they work out how deep features such as pits and post-holes are, they define layers and structures, and describe them, either verbally or by writing in on-site records.  These decisions are every bit as important to the outcome of the excavation as the those taken by people in more senior positions.

 

 

 

Where modern survey methods, such as geophysics, give such a clear and detailed impression of archaeology without the need for excavation, why do we need to excavate at all?

There are some types of information about the past which are only understandable through excavation.  Survey techniques can tell us what structures may exist below-ground, and we can interpret the results of topographical and geophysical techniques to suggest that there may for instance be a Roman fort, or medieval church, preserved in the ground.  However, experience suggests that the archaeological deposits are probably much more complex than we may suspect: survey is very good at revealing some indications but often misses others.  Artefacts, burials, mosaics, organic matter which can be radiocarbon dated and environmental information such as seeds and pollen, are all largely or completely missed by survey techniques, but are retrievable by excavation.  We cannot X-ray sites to give us information of this complexity, it must be excavated.

 

There will always be a need for excavation, even with a preference in the planning system for ‘preservation in situ’.  Some sites simply cannot be left as they are, because natural or development-related destruction is inevitable.  Skilled and experienced excavators will therefore always be required.  These people need to begin their excavation training during their education as archaeology students, away from the pressure of rescue excavation, so special training excavations will always be necessary too.  Archaeology is a lively academic discipline, and some excavation (often combined with training purposes) is necessary for some research questions to be answered.   No reputable archaeologist would undertake excavation lightly - only if they are sure that the potential benefits of new information and training outweigh the potential loss of in-situ archaeology would they go ahead.

 

If a site is not due to be completely destroyed by development, it is good practice not even to try to excavate all of it.  Archaeologists are aware that their techniques and equipment are in a constant state of innovation and improvement.  Our excavations today are much more effective at retrieving information than those of, say, 1950.  However, those of 2050 will be far more effective than today’s.  Computer technology has, and will, make a huge contribution to effective archaeological practice. There may be things to which we are paying no attention to at present, but which will become very important in future for our understanding of the past.

 

 

The question where to dig is crucial to the success of the excavation. It is rare for archaeologists to dig 100% of a site, even if it faces total destruction from development afterwards.  Archaeologists have to decide which parts of a site to concentrate on in order to retrieve maximum information within the available time.  A number of objectives will be set for the investigation, perhaps investigating features which have been revealed in pre-excavation survey, perhaps to gain an understanding of the date or ground-plan of the structures present, or possibly to excavate a certain proportion of each major deposit or chronological phase.  These objectives will inform the decision on the number and size of the excavation trenches.  Trenches are often positioned where as many objectives as possible can be tackled in one place: such as a point where a later building is built over an earlier building, or where two ditches or walls cross each other.

A regular, or possibly deliberately random proportion of the archaeology may be investigated on the assumption that it will provide a representative picture of the whole site: this is called ‘sampling’. There are many kinds of sampling strategy, but the one factor they all have in common is that they are designed to achieve maximum information across the site from each excavated area. Some archaeologists prefer to have a flexible and informal sampling strategy so that respond pragmatically to new information and interpretation during their field project. Others prefer to have an explicit and pre-formulated strategy so that they can be sure they have investigated certain proportions of the available area and deposits.

Excavation takes place within trenches or areas.  These are located within a site survey ‘grid’ so that every point on the excavation site can be given a horizontal co-ordinate.  A benchmark is established from which vertical measurements can be taken.  These are important because recording the locations of structures and finds, in both vertical and horizontal dimensions, is an essential aspect of excavation.  Trenches range in size from 1 metre square test pits and slightly larger evaluation trenches giving a ‘glimpse’ of the archaeology in the ground, to sections of individual settlements, burial areas or ditch systems.  On very large excavations, such as those required before major developments such as new towns, airports or motorways, there are open areas of many hundreds or even thousands of square metres, covering multi-period archaeological landscapes of settlement, agriculture and industry.