Mapping the Site
Archaeology Defined
The Feature System
Key to successful excavation of an archaeological site is accurate mapping. The archaeological crew arrives on-site and then must record location, topography, and surface artifact distributions. There are no precise formulas for proper mapping since unique site situations require creative solutions.

A general procedure is outlined here:
Site Found: Quicky Survey or Testing
Figure 1. Declination.
Figure 2. Reproduced section of U.S.G.S. quad "Firth, Idaho." Site locations will typically emphasize topographic landmarks and permanent features like maintained roads, wells, streams, and telephone lines.
Often the field crew will use a hand-held compass or Brunton for laying out site datums, reference lines, and maps.

-The archaeological site must be plotted on a U.S.G.S. quad sheet and the legal description (T-R or UTM) noted. Location should include a brief description of site locale, emphasizing easily recognizable landmarks (topography, streams, roads) and describing access to the site area.

-The crew will have to decide if reference is to magnetic north or true north, adjusting for declination as indicated on the U.S.G.S. quadrangle (quad sheet).

-The crew uses the Brunton to shoot a cardinal reference line (N-S or E-W). A stake marks the datum to be established and another marks the end of the line. If this baseline is to be used for a test trench, the crew may run a metric tape from stake to stake, marking off one meter excavation units or squares.

-The grid should be numbered within the NE quadrant, assuming a reference datum set well off the site surface to the SW. Usually, the grid datum is set as 100N 100E. This convention will allow for expansion back to the SW if necessary and ensures consistency by allowing only grid references drawn within the quadrant defined by the North and East axes.

-(Figure 2) A sketch map should be made of the site prior to excavation. This sketch map should indicate major artifact concentrations, locations of stream channels and roads or other features, and the layout of the cardinal grid line.

-It is very important at this juncture that the field crew note all surface evidence that might pertain to the nature of site disturbance.

-If testing is required, grid units should now be selected for excavation. Generally, any testing should try to randomize the distribution of excavation units. This proviso should also be intepreted, however, with common sense. If cultural features are visible on the surface or in stream erosion banks, or if artifact distributions show obvious clustering, the sample should be stratified and encompass arbitrary placement of excavation units.
Site Recording Procedures: Keeping Control
The key to successful excavation is maintaining accurate measurements or provenience information throughout the exercise. Two reference systems must be slavishly adhered to:

-All horizontal and vertical measurements must be taken from the primary or secondary site datums.

-All excavation squares and excavation levels must be labeled within the establish quadrant of one meter grid squares.

Figure 3. The site grid reference system.
In Figure 3, excavators have laid out a one meter by one meter grid system labeled as north and east axes. Seven 50cm by 50cm test units have been selected and diagnostic artifacts have been located as letters a-k. A primary datum has been set at 100N 100E and a secondary datum set at 106N 104E.

Concern for adequate CONTROL must also dictate excavation strategy:

Mundane but very important: Make sure that the excavation unit is absolutely square (an error at the beginning is a fatal flaw in the analysis and publication). Excavators should use two metric tapes and the concept of a 3-4-5 triangle to square unit corners.

Mundane but equally important: Make sure that all excavation units are designated by their southwest corner referenced within the NE site grid system. A common mistake is to confuse excavation unit coordinates as excavation progresses.

Mundane again, but oh so common a mistake: Make sure that the strings on the stakes are crossed on the inside so that excavation margins do not prematurely remove the stakes.

If level readings are being taken from the SW corner of the excavation unit, be sure to notch the corner stake rather than letting the level string slide down as the site surface erodes. This string elevation will be shot relative to the primary datum elevation.

Excavation will normally proceed in arbitrary 5 cm or 10 cm horizontal levels within the excavation units. As excavation expands into adjacent units, arbitrary levels will generally be abandoned for natural or cultural levels. A this point, elevations will be taken on the surfaces of the naturally sloping and diving strata.

Figure 4. Plotting the position of artifacts on the floor of an excavation unit.
Figure 4 indicates how control is kept on accurate measurement of the vertical and horizontal provenience of artifacts within the excavation units. A number of artifacts are plotted on the north and east axes of unit 100N 100E. Each artifact has been given a specimen number (FS 160) unique to the unit and stratum. Feature boundaries (F16) are roughed in as indicated.

As excavation proceeds, the crew is recording tactics and observations in the feature system forms. Done correctly, this record supplies the information that will be sought by analysts, report writers, and other researchers.

Rigor is essential. Remember that excavation is destruction, and is only justified if the utmost care is taken to record all relevant information.
Recommended References

Barker, Philip

Hester, Thomas, Harry J. Shafer and Kenneth L. Feder (eds.)

Jaukowsky, Martha