Interview with E. Harris: "the stratigraphic sequence is, in a sense, the DNA model of each sit

3/4/15 .-

Interview with Edward Harris: "the stratigraphic sequence is, in a sense, the DNA model of each site"

Edward Harris has passed into history of Archaeology due to his decisive contribution: the Harris Matrix. A complex method that has spread around the world since 1973 and is still using by a lot of archaeologists. He has recently visited Madrid, moment that we have used to interview him. Here is our conversation.

Question - You invented the Harris Matrix in 1973. Please, could you remind us how you developed this model/method and why?
Answer - The Harris Matrix was invented in the evening of Wednesday, 28th February, 1973, when I was working late that day on a major problem of the interpretation of records from a large archaeological site, which was excavated at Winchester, England, between 1967–71. The problem was to construct a ‘stratigraphic sequence’ (as we later understood that phrase) from the records of the excavations, in that instance some seventy (70) site notebooks, and several hundred composite-plan and section drawings. (It was an impossible task, as many archaeologists have found when working on records that did not have the benefit of using the Harris Matrix and associated methods and laws.) That interpretation of the archives of the excavation was conducted verbally, by trying to sort out the relationships between the ‘layers’ and ‘features’ by reading descriptions, trying to put the items in stratigraphic order, and then if a conclusion was reached for a group of such material, the items were re-written in ‘phase order’.

The trouble was that one could not remember all the stratigraphic relationships that were expressed in words, or text, even for a few dozen units, let along the 10,000-plus units represented in the 70 site notebooks. (It was impossible then, and would be impossible now, without the help of the Harris Matrix). I thought that I needed to see the relationships, that is visually, rather than verbally (as text) and began to make incipient Harris Matrix images on clear mylar paper, which happened to be overlain on a piece of metric graph paper. I started doodling and tracing half-centimeter rectangles with spaces in between, and after I had several dozen of those, I suddenly knew that the world had changed for the stratigraphic interpretation of the records, as I had a format into which the stratigraphic data could be put, and in which it could be seen, instead of read. I continued to draw the rectangles late into the night and called the final sheet of the ‘boxes’ the ‘Harris Matrix’, that is to say, a matrix, or form, into which the stratigraphic data could be inserted.

In keeping with the mind-set of the times, I called such data ‘layer charts’, but of course, we later knew these were ‘stratigraphic sequences, as such a sequence has to include layers (deposits) and surfaces. It then took several years to figure out what a ‘Harris Matrix’ actually represented and what archaeologists were not recording, so as to be able to make stratigraphic sequences after the end of an excavation. (We now known that stratigraphic sequences must be made during the excavation, not afterwards). I was fortunate that starting in 1976, I was able to do my doctoral thesis at University College London on the ‘principles of archaeological stratigraphy’, as a research investigation on that subject had never been done before. That was thanks to acceptance of the idea by Professors David Wilson and James Graham-Campbell at the Department of Scandinavian Studies at UCL. The these was accepted in December 1978 and the small book Principles of Archaeological Stratigraphy was published in late 1979 by Academic Press: the rest, they might say, is archaeological history!

Question - Carandini and Manacorda have talked about a "Harris phase" in archaeology in the same way as we can talk about a "Wheeler phase". What do you think about it and what causes are involved in the world success of the Harris Matrix?
Answer - The two phases are actually one, in a sense that they are perhaps the first and second parts of the revolution in archaeological methods as regards the ‘stratigraphic approach’, as opposed to excavations that take place by destroying the Past by digging in measured levels, rather than by the stratigraphic makeup of a site. It might be said the Sir Mortimer Wheeler and Dame Kathleen brought stratigraphic excavation into the modern age and also brought focus to stratigraphic recording. That revolution evolved significantly in the 1960s, with the emphasis on excavation in large trenches (‘open-area excavation’). That is to say, that surfaces began to take a significant place in stratigraphic excavation and recording, but the latter, as far as recording of surfaces went, was of a qualitative nature, almost trying to represent surfaces as if they were sections, that is to say, composite surfaces were recorded, rather than individual ones. In other words, the culmination of the Wheeler era ended in the realization that the main emphasis in excavation should be on the attention to surfaces over the stratigraphic evidence of sections. To put it into modern parlance, “If you take care of, and record, individual surfaces, sections will take care of themselves’, because with computer programmes, you can recreate section profiles wherever desired, provided that the surfaces are individually recorded.

The Harris Matrix can be said to be a product of the problems created by the refinement of excavation and recording methods of the Wheeler Era, since many sites after the 1950s, particularly in urban settings, began to record thousands of stratigraphic units, but were recording them under the Wheeler-Kenyon methods. That data was literally locked into notebooks, as opposed to using individual forms for each unit, and locked into composite surface plans (sections by their nature lock in data, as it cannot ever be presented other than as recorded). The major missing ingredient in the Wheeler Era, which might be said, from 1973, to user in the ‘Harris Era’, was the concept of a true stratigraphic sequence, being the diagrammatic illustration of the buildup of all the stratigraphic units of a site, and representing in such diagrams the three physical dimensions of the stratification of a site plus the fourth dimension of relative time. The other significant missing stratigraphic ingredient was the recording of all surfaces before the excavation of deposits that support such surfaces. Surfaces are like time, for they do not visibly exist unless they are recorded.

Every archaeological site has a unique stratigraphic sequence and that is their value to history. The stratigraphic sequence is, in a sense, the DNA model of each site, but while each is unique, they can be compared via the Harris Matrix, as the stratigraphic sequences compiled by its methods are not based upon cultural context and content, but from the record of the stratification of a site: stratification is everywhere the same, being the duality of surfaces and deposits and surfaces without deposits. The analysis of stratification in order to compile a stratigraphic sequence is best ascertained by the study and record of surfaces and that represents one of the major revolutionary changes from the Wheeler to the Harris Eras. The Wheeler Era coud be said to be represented by the one-dimensional paradigm of the ‘section’ (depth) and in its last phases by the two-dimensional paradigm of the plan (area: length and width). The Harris Era replaced those inadequate icons with the four-dimensional paradigm of the stratigraphic sequence, as represented by Harris Matrices. Such 4-D illustrations are the unbiased testing patterns against which most other analysis of the site and its artefacts must be evaluated.

Some archaeologists claim it is unnecessary to use the Matrix on their excavations, especially if they are excavated in geological materials. That is an unfortunate assertion, as geologists do not have a way of demonstrating true stratigraphic sequences, as archaeology can do with the Harris Matrix, and stratigraphically, for excavation, recording and analyses, there is no difference, stratigraphically, between geological and archaeological stratification: they are both composed of surfaces and deposits. If one considered the contexts of geologically deposits to be but a different culture, one can see that they should be treated the same as an ordinary archaeological site with no geological deposits.

The success of the Harris Matrix (now accepted by many archaeologists around the world as the only way to approach the recording and analyses of sites) lies in the fact that it was, from its inception, a ‘true’ scientific method, and thus any problems with it were due to bad stratigraphic data, not with the method. The Harris Matrix has given stratigraphic archaeology a new four-dimensional paradigm and the only way to see the stratigraphic sequences of archaeological (and geological) sites. The fact that in its forty-second year it shows no sign of losing its power underscores its fundamental value to archaeology, for any number of reasons.

Question - How has evolved the Harris Matrix from its origin to this moment?
Answer - The Harris Matrix has remained fundamentally the same, which is part of its value, as it represents unchanging truths from archaeological sites. What has evolved are the many different types of stratigraphic situations to which the Matrix and its methods are applied, be it rock art and other types of painting, standing buildings stratigraphic analyses, and various forms of forensic work, to name but a few. The fact is that much of the world is stratigraphic in nature, not just the usual contents of archaeological sites.

Question - In your opinion, which will be the next steps in the development of your model? Are you working on it right now?
Answer - The next stages for the Harris Matrix is to impose its standards worldwide and in particular to ensure that its methods become a inescapable part of the ethics to which archaeologists and archaeological societies should be adhering: the latter is something of a desert at the moment and many archaeologists are yet destroying sites by non-stratigraphic excavation and by the same token, un-stratigraphic recording. To those end, the textbook on Principles of Archaeological Stratigraphy is available for free at in six languages. Always an expensive book and never in softback, I bought out the publisher to get the copyright back and my colleagues Dr Wolfgang Neubauer and Dr Klaus Locker at University of Vienna made and maintain the website for the benefit of any archaeologists who wants to do their job correctly and professionally.

Question - You have developed a software to manage an excavation project by building up a Harris Matrix, could you talk us about the advantages of this software?
Answer - The Harris Matrix Composer has been developed by my colleagues at the University of Vienna, but I have no financial interest in the programme. One of the main advantages of that computer programme, as with some others, is that it makes the drawing of stratigraphic sequences very easy, as compared to the problems of arranging and drawing it by hand.

Question - What do you think about the application of this kind of protocols to 3D reconstruction?
Answer - The Harris Matrix brought in the stratigraphic revolution in archaeology and changed its paradigm from one to four dimensions: that was all done by hand. The advent of the personal computer has greatly enhance the value of the Matrix by speeding up recording and the analyses of records, particularly with 3-D scanning, GIS systems for drawing, the drawing of stratigraphic sequences, the analyses of artefacts and other matters pertaining to archaeological sites. It is fair to say that with the Harris Matrix at hand and computerization for rapid recording and analyses, that archaeologists have the best chance now to do their job as excavators, stratigraphers and site analyses competently and professionally, as was perhaps almost impossible before the Matrix and such general technological advances in computing power.

In the end, one of the most important task after the end of an excavation is the reconstruction of the site: that reconstruction is the reconstruction of surfaces, of landscape phases and periods. Few archaeological sites before the Harris Matrix can be so reconstructed as only a small quantity of individual surfaces were recorded. Many sites, in effect, have been excavated into oblivion. The reconstruction of surfaces (one of the two types of phases and periods on archaeological sites) cannot be accomplished without individual plans of every surface on a site, and without computers, the drawing of phase and period plans (designated after the analyses of artefacts, but in compliance with limits of each stratigraphic sequence) would be almost in possible to do by old manual methods.

For archaeologists, the methods of principles of archaeological stratigraphy and the applications of modern computerization are a marriage made in heaven, and for which there will never be a divorce. Sites before the Harris Matrix, that is as one archaeologist has written, “Sites without Principles”, are likely to be a stratigraphic living hell, if one tries to do after the fact what should have been done during the excavation: namely, the compilation of the stratigraphic sequence (Harris Matrix) of the site. That is what the Harris Matrix endures: it is the indispensible tool for excavations and the indispensible method for representing the essence of archaeological sites: their unique stratigraphic sequence, which is the foundation for all later analyses and interpretation of each and every such site, anywhere in the world.

Mario Agudo Villanueva

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