2. Topography (“volumetry”)

Giorgio Buccellati – November 2009

Concepts
Sections and profiles
Loci and squares
Plots and floor plans
Geo-referentiality
Techniques of measurement
The different uses of the grid

Concepts

It is customary to speak of squares and loci as “arbitrary.” This refers to the fact that they are constructs imposed by the excavator and not original data found in the ground. But the term “arbitrary” may also imply unjustified whim. For this reason, I prefer to describe such constructs as volumetric referents – “volumetric” because they deal with the measurement of volumes, and “referents” because, inasmuch as they apply values to the data in the ground, they insert them in a broader and explicit referential web.

Topography (also: “positioning”) is the best known part of this process. Accordingly, this is the term used in the left sidebar, although the pertinent section includes more than what is normally associated with this term.

Sections and profiles

Sections represent one of the most important operative concepts in archaeology. They are in effect one and the same with loci, since they represent the vertical cut that corresponds to one of their faces. (I use the term “profile” to refer top the graphic rendering of the physical cut.) Accordingly, profiles are found in the analytical part under any given locus.

Typically, for each locus we draw the profile of the northern and the eastern section. These will be found both as photographs and as drawings under the pertinent locus.

Where sections are linked across several loci, they are given as part of a combined drawing that joins together the component profiles. Where necessary, a special locus is created that subsumes the pertinent individual loci.

Loci and squares

Loci and squares are described in the grammar under the heading of complex referents.

A locus is a volumetric unit with minimal horizontal axis of undefined size, and with unlimited vertical axis. Loci are generally used for smaller test soundings, or, conversely, to subsume, two or more squares.

A square is locus with a preset size of 5m on the side. Squares are integrated wihin a preset geometrical grid, so that the corresponding labels follow a predetermined sequence.

Plots and floor plans

Floor plans are generated from plots that reproduce a schematic outline of elements found in the ground and represented according to their coordinates.

Geo-referentiality

Since the beginning of the project, all measurements taken in the field, whether by the surveyor or by the excavators, have been geo-referenced, in wo distinct ways.

At the beginning, we could not obtain a specific UTM set of coordinates for the site. So our grid, established by Stephen M. Hughey, gave the coordinates of 500E and 500N to the geodesic point found at the top of the tell. It also assigned to it the value of 500.00m as absolute elevation, based on general elevation measurements found on commercially available maps.

Techniques of measurement

From a theodolite used at the start of the project in 1984 we moved on to a total station in the early nineties. These instruments give the higehr degree of precision and are used only by the surveyor to lay (“markers” and “benchmarks.” These are used either as points that define referents (especially loci) and elements (occasional architectural features or location of special items), or as control points from which other points (“relays“) are measured by the excavators.

Because of the quantity of measurements taken, and the cost that would be entailed in having total stations available in each excavation units, relays are still taken with a simple device, which we call “triangulation rod,” and which is described in detail in the website section on techniques.

Other advanced techniques, i particular photo-modelling and a laser scanenr, have been used on an experimental basis by Prof. Maurizio Forte. A separate report will be forthcoming in the website.

The different uses of the grid

There are two distinct conceptions of the grid, although the distinction is not generally appreciated. In the first place, the grid is a referential concept – a network of ideal lines that crisscross a site and allow to easily correlate any given location in space to a location on a scaled plane or even on a three-dimensional space, whether on paper or on a computer screen.

In a second instance, the grid is conceived as a physical entity that is overlaid on the site itself, by means of stakes and strings.

At Mozan, we do not use the physical grid. And while we have a conceptual, or referential, grid, we do not in effect use that either – at least not as a grid. We only use points of two different degrees of precision, markers and relays. So it may be said that we use a grid of points rather than a grid of lines.

An important consequences that flows from this is that we have used a number of different physical grids, with different orientation depending on the special conditions of the terrain and of the excavation strategy.