The Principles of Stratigraphy

1. The Principles of Stratigraphy

2. Stratigraphy The stratigraphic principle was adopted for archaeology during the 19th century from the geological sciences The first stratigraphic excavation of a Tell site was conducted by H. Schliemann at Troy (Turkey) between 1871 and 1890 The first stratigraphic excavation in the Levant was undertaken by W. M. F. Petrie at Tell el-Hesi in 1890

3. Understanding a Tell How does a Tell develop?

4. Problems in applying the stratigraphic principle - While the stratigraphic principle was soon widely accepted and used for conducting excavations, some problems were encountered. At Byblos during his excavations during the 1920ies, M. Dunand considered the division into layers as being too subjective. He instead chose to excavate in artificial, absolutely horizontal layers of 20 cm thickness (as a consequence, no one has been able to produce correct plans of the architecture of the different layers)

5. Problems when only relying on the absolute height Already M. Wheeler has pointed out that objects and features with the same absolute level may not need to be contemporary

6. The Case of Ugarit (Syria) In his excavations at Ugarit from 1929 onwards C. F. A. Schaeffer divided each period into three layers. It it clear that this tripartite subdivision does not represent the stratigraphical reality, but an evolutionary model representing the emergence, flourishing and decline of a period.

7. Especially when dealing with a complex site such as a Near Eastern Tell, a rigid application of the stratigraphic method becomes absolutely necessary!

8. Thus, on a Tell the different layers (or contexts) do not represent cultural stages or historical periods, but subsequent events of erection, use and abandonment of structures

9. Only with the help of datable artifacts from the contexts these can be placed in their cultural or historical context

10. The laws of archaeological stratigraphy - The law of superposition The law of original horizontality The law of original continuity The law of stratigraphic succession

11. 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 (Harris 1989, 30)

12. The Law of Original Horizontality 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 pre-existing basin of deposition (Harris 1989, 31)

13. The Law of Original Continuity Any archaeological deposit, as originally laid down, or any interfacial feature, as originally created, will be bound 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 (Harris 1989, 32)

14. The Law of Stratigraphical Succession 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 (Harris 1989, 34)

15. The Harris Matrix The Harris matrix is just a way to illustrate complicated stratigraphical relationships in the way of a flowchart This way of illustrating the stratigraphy becomes absolutely necessary when dealing with large excavation areas with a complicated stratigraphy Some excavations contain more than 10.000 stratigraphical units. Here a special computer program for establishing and checking the Harris matrix is required

16. The Harris Matrix The Harris matrix recognizes only three types of relations between stratigraphical units: A: no connection; B: superimposed; C: part of the same deposit

17. Application of the Harris Matrix An example of a plan showing all features excavated in an area. Without a Harris matrix the exact relationships between the different features can not be established in a three-dimensional way

18. Application of the Harris Matrix An example of a Harris matrix with subdivisions into periods and phases

19. The Concept of Interfaces An interface is the border between two layers or features. These interfaces are very important, as often it is only on these interfaces that human action took place

20. Interfaces • Take the case of a pit for instance, where only the interface may give indications of the use of the pit, whereas the fill may have come in at a much later time • Equally floors may be represented only by the uppermost part of layer, thus this floor has to be distinguished from the fill below

21. Section drawing without indication of the interfaces

22. Section drawing with the interfaces