Back to top: Edward Harris
Excerpts from Harris 1975 Stratigraphic Sequence
Back to top: Edward Harris
Excerpts from Harris 1975 Stratigraphic Sequence
| Stratigraphy | is the descriptive study of archaeological strata (the smallest recognized division of a site, physical or otherwise, generically referred to as 'layers'), their occurrence, soil or filling content, artefact content, succession, and classification with a view to arranging them in a chronological sequence. Stratigraphy is not a principle but rather an area of study. |
| Stratification | is any number of relatable deposits of archaeological strata which are the result of 'successive operations either of nature or mankind' (Wheeler in Rapport and Wright 1963: 47). |
| The Principle of Stratigraphy | is that an object left on or in the soil at any given time will be found at a lower level than one deposited later. |
| Stratigraphic Sequence | The redefinition of 'stratification' necessitates the use of the stratigraphic sequence which is a name for the relative chronology of a site as deduced from its stratification. Constructed by the rearrangement of stratification it is a statement in four dimensions, the fourth being Time which has an 'event' as its smallest element. |
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Excerpts from Harris 1979 Archaeological Stratigraphy
| The Law of Superposition | in a series of layers and interfacial features, as originally created, the upper units of stratification are younger and the lower are older, for each must have been deposited on, or created by the removal of, a pre-existing mass of archaeological stratification. |
| The Law of Original Horizontality | any archaeological layer deposited in an unconsolidated form will tend towards a horizontal disposition. Strata which are found with tilted surfaces were so originally deposited, or lie in conformity with the contours of a pre-existing basin of deposition. |
| The Law of Original Continuity | any archaeological deposit, as originally laid down, will be bounded by a basin of deposition, or will thin down to a feather-edge. Therefore, if any edge of the deposit is exposed in a vertical plane view, a part of its original extent must have been removed by excavation or erosion: its continuity must be sought, or its absence explained. |
| The Law of Stratigraphic Succession | any given unit of archaeological stratification takes its place in the stratigraphic sequence of a site from its position between the undermost of the units which lie above it and the uppermost of all those units which lie below it in which it has a physical contact, all other superpositional relationships being regarded as redundant. |
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Excerpts from Harris 1989 Principles Archaeological Stratigraphy
| stratigraphy and geology | p. xii | [M]ost of the stratigraphic problems in archaeology today stem from the fact that we did not divorce ourselves long ago from geological notions of stratigraphy, which are entirely useless in many archaeological contexts. [...] Stratigraphically speaking, it is from a very early point in human history that geological principles of stratigraphy were no longer applicable to man-made stratification: It is from that early time that a claim for 'archaeological stratigraphy' as a separate, earth-forming process, cannot be refuted. |
| laws in geology p. 5 |
There were three axioms which pertained to rock strata: the Laws of Superposition, Original Horizontality and Original Continuity. | |
| p. 6 | Despite the fact that these geological axioms have caused considerable difficulties for archaeologists, there is a new group (e.g. Gasche and Tunca 1983) in our midst who advocate their reintroduction. | |
| p. 8 | [M]ost archaeological stratification is man-made and is not directly subject to the laws of geological stratigraphy. | |
| pp. 29-30 | The application of these geological laws without revision in archaeological stratigraphy may be questioned for two reasons. On one count, these laws relate to strata which were usually solidified under water and may cover many square miles. Archaeological strata, by contrast, are unsolidified, of limited area and of diverse composition. In the second instance, artefacts cannot be used to identify strata, in the sense implied by geological laws, if only because they have not evolved through natural selection. | |
| types of excavation | p. 15 | There are two processes of excavation, the arbitrary and the stratigraphic. Arbitrary excavation is the summary removal of soil by any possible means, or its controlled excavation in measured levels of a predetermined thickness. In stratigraphic excavation, the archaeological deposits are removed in conformity with their individual shapes and contours, and in the reverse sequence to that in which they were laid down. Either of these processes may be used with any of the several different strategies. |
| p. 20 | It is now generally agreed that the process of stratigraphic excavation should be employed where archaeological layers and features can be recognized in the stratification of a site. In other instances, the units of stratification may not be recognizable, and the arbitrary process of measured spits may be used. The interpretations based on the results of excavation areas dug in spits must be treated, however, with considerable scepticism, in any stratigraphic analysis. Using arbitrary levels will always be making the best of a bad job. It is also now agreed that the area-excavation strategy is often the most desirable course of action upon which an excavator should embark. |
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| laws of stratigraphy (archaeology) | Law of Superposition p. 30 p. 31 |
In a series of layers and interfacial features, as originally created, the upper units of stratification are younger and the lower are older, for each must have been deposited on, or created by the removal of, a pre-existing mass of archaeological stratification. |
| The law is simply a statement about the physical relationships of superimposed deposits, i.e. one lies on top of or underneath another, and is therefore later or earlier. | ||
| Law of Original Horizontality p. 31 |
Any archaeological layer deposited in an unconsolidated form will tend towards a horizontal position. Strata which are found with tilted surfaces were originally deposited that way, or lie in conformity with the contours of a preexisting basin of deposition. | |
| The Law of Original Horizontality assumes that strata, when forming, will tend towards the horizontal. | ||
| Law of Original Continuity p. 32 p. 33 |
Any archaeological deposit, as originally laid down, or any interfacial feature, as originally created, will be bounded by a basin of deposition, or may thin down to a feather-edge. Therefore, if any edge of a deposit or interfacial feature is exposed in a vertical view, a part of its original extent must have been removed by excavation or erosion, and its continuity must be sought, or its absence explained. | |
| This correlation is made on stratigraphic grounds, without regard for the artefactual content of the deposits. The parts of the strata must be correlated by their soil composition and by their similar relative positions in the stratigraphic sequences on either side of the intrusive feature. | ||
| Law of Stratigraphic Succession p. 34 |
A unit of archaeological stratification takes its place in the stratigraphic sequence of a site from its position between the undermost (or earliest) of the units which lie above it and the uppermost (or latest) of all the units which lie below it and with which the unit has a physical contact, all other superpositional relationships being redundant. | |
| It is now an accepted fact that the Harris Matrix provides archaeology with a method by which stratigraphic sequences can be diagrammatically expressed in very simple terms. | ||
| Harris Matrix | p. 34 | The Harris Matrix is the name given to a printed sheet of paper which contains a grid of rectangular boxes (Fig. 8). The name has no other connotation, mathematical or otherwise: it is simply a format for exhibiting the stratigraphic relationships of a site. The resulting diagram, which is often called a 'matrix' in shorthand, represents the stratigraphic sequence of the site. A 'stratigraphic sequence' is defined as 'the order of the deposition of layers and the creation of feature interfaces through the course of time' on an archaeological site. |
| relation between units p. 36 |
The Harris Matrix system recognizes only three relationships between units of archaeological stratification. (A) The units have no direct stratigraphic connection. (B) they are in superposition; and (C) the units are correlated as parts of a once-whole deposit or feature interface. | |
| stratification | p. 36 | The primary object of the study of archaeological stratification is to place the units of stratification, the layers and the features, into their relative sequential order. The stratigraphic sequence can and should be constructed without reference to the artefactual contents of the strata. |
| p. 42 | Archaeological 'units of stratification' represent an archaeological aspect of time's cycle. They are of universal character and can be found on any archaeological site in the world. | |
| interfaces | p. 54 | Archaeological stratification is a combination of strata and interfaces. While it may be argued that a layer and its interface, or surface, are a single phenomenon, it is necessary to distinguish between them in stratigraphical studies. Other interfaces are created by the destruction of strata and not by their deposition. |
| p. 68 | Stratification is, however, a record which has both positive (deposition) and negative (erosion or destruction) elements: both should be recorded equally. | |
| sections | p. 69 | An archaeological section is a drawing of a vertical soil profile, as exhibited by cutting down through a mass of stratification. Two things are shown in a section: a vertical plane view of the strata, and the various interfaces between the bodies of the strata. |
| p. 71 | On complex archaeological sites, sections cannot give a representative view of the stratigraphic sequence of a site. It is extremely difficult on such sites to choose a line for a section which would give a 'representative vertical view' of the stratification, as the orientation of features on the surface may not be that of those below. Sections, moreover, only record the physical relationships of the stratification at a given point. | |
| p. 76 | More than any other method of recording sections, the cumulative section fulfils the requirements of modern archaeological stratigraphy. Should it be desirable to have a baulk or two on a site for whatever reasons, the standing section can be recorded in a cumulative fashion as the excavation proceeds. |
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| p. 78 | If a stratigraphic use is to be made of section drawings, the rule is that it is the interfacial lines that count, because it is only by their analysis that any sense can be made of the stratification of a site. | |
| plans | p. 82 | The shift of interest from sections to archaeological plans has been due to the introduction of modern methods of open-area excavation. |
| p. 83 | With incomplete boundary contours, it is difficult or impossible to work out the stratigraphic relationships between the layers which are recorded in a composite plan. | |
| p. 95 | The single-layer plan is the least that an archaeologist must do to record the topographical remains of each unit of stratification. The method (as suggested to the writer by Laurence Keen and developed with Patrick Ottaway) is very simple. Pre-printed sheets (Fig. 38) are provided to the excavator. On each sheet, only one unit of stratification is recorded. This record is one of essentials, not of intricate details. The essentials are a set of co-ordinates, the plotting of the boundary contour of the layer or feature, and an appropriate number of elevations. The elevations are placed directly on to the plan, for convenient reference. As each new unit of stratification is defined, the same format of recording is carried out. This method records all of the non-historical aspects of each unit of stratification, which are repetitive and universal. |