Archaeological plan

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In an archaeological excavation, a archaeological plan is a drawn record of features (and artifacts) in the horizontal plane. It can either take the form of a "multi context" plan, which is drawn with many contexts on it to show relationships between these features as part of some phase or alternatively a single context plan with a single feature is drawn . Excavated features are drawn in three dimensions with the help of drawing conventions such as hachures. Single context planning developed by the Museum of london has become the professional norm. The basic advantage of single context planning is contexts can overlaid for re-interpretation at a later date. Plans can be made of complete sites, trenches or individual features. Their scale is usually 1:20 in the united kingdom. They are linked to the site recording system by the inclusion of known grid points and height readings, taken with a dumpy level or a total station (see surveying). Excavation of a site by the removal of deposits in the reverse order they where created is the preferred method of excavation and is referred to as stratigraphic area excavation "in plan" as opposed to excavation "in section".Plan and section drawings[[1]] have an interpretive function as well as being part of the recording system, because the draughts-person makes conscious decisions about what should be included or emphasised.

fig 1.Typical single context plan

1 The grid
2 Planning drawing conventions
3 Pre-excavation and base plans
- 3.1 critics of pre excavation planning
4 See also
5 References

[edit] The grid

It is common and good practice on excavations to lay out a grid of 5m squares so as to facilitate planning. This grid is marked out onsite with grid pegs that form the baselines for tapes and other planning tools to aid the drawing of plans. It is also common practice that planning is done for each context on a separate piece of perma-trace that conforms to these 5m grid squares. This is part of the single context recording system (see Fig 1.) The site grid should be tied into a national geomatic database such as the Ordnance survey

[edit] Planning drawing conventions

Archaeological planners use various symbols to denote characteristics of features and contexts and while conventions vary depending on practioner the following are representative.

Fig 2. edge of context conventions

Fig 3. Cut planning hachures

[edit] Pre-excavation and base plans

On rural sites with little stratigraphic depth a pre-excavation multi context plan is sometimes made of all visable feature before any excavation is carried out. this helps in planning startergy since problems of stratigraphy on rural sites cut into natural minimize issues of inter-cutting features that make planning a urban site multi contextually so difficult.

[edit] critics of pre excavation planning

Pre excavation plans have been critiqued as being of limited use on urban or deeply stratified sites and have also been attacked in professional archaeology where they have been discribed as a misused tool of the unscrupulous operators to give the impression the archaeological record for a given site has been dealt with adequately.

There is also the point of view, that the comparisons that can be drawn between pre and post excavation plans can demonstrate that a site has been comprehensively excavated. In many cases there is a pronounced difference between the two phases of planning. Although many features may be visible at ground level following machining it is often the case that the true limits of features are not so initially discernable until the area of the feature is fully cleaned and subsequently excavated. This however, is probably more applicable to open field or rural sites than the above mentioned deep stratified and urban sites.

Paul Gelderd 14:18, 17 November 2006 (UTC)