CAA 2019 Krakow - When Harris met Allen in The Matrix: How can the conceptual modelling of stratigraphic relationships facilitate deeper understanding of archaeological space and time?
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CAA 2019 Krakow - When Harris met Allen in The Matrix: How can the conceptual modelling of stratigraphic relationships facilitate deeper understanding of archaeological space and time?
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CAA 2019 Krakow - When Harris met Allen in The Matrix: How can the conceptual modelling of stratigraphic relationships facilitate deeper understanding of archaeological space and time?
- 1. When Harris met Allen in the Matrix Keith May, Historic England | & University of South Wales | How can the conceptual modelling of stratigraphic relationships facilitate deeper understanding of archaeological space and time? Steve Roskams & James Taylor | Department of Archaeology, | University of York
- 2. Digital Stratigraphy: Digital Tools Harris Matrix Composer Bonn/ArchEd - Matrix layout
- 3. Digital Stratigraphy: Principles Stratigraphic laws/analysis are fundamental methodological approach in many recording systems. Harris (1979) asserts three main areas of study: ● Theories and laws ● Recording ● Post-excavation analysis “As stratigraphic sequences are abstractions, they can be demonstrated in writing or by schematic diagrams.” (Harris 1979, 111) Harris 1979 - Fig 2
- 4. Digital Stratigraphy: Practice But... ● Limited consistency in digital stratigraphic data ● Less consistency for higher order grouping ○ (especially phasing) ● Problems with representation of analytical groups ○ (relationship between phases groups & contexts) “Turning next to data manipulation after excavation, there is a great need to sort out the concepts used in stratigraphic analysis … to match the systematization which has been developed in the production of the site record. For the most part what is needed is intellectual clarity in defining concepts and then labelling them” (Roskams 2001, 278-279)
- 5. ● Variability of stratigraphic data held in digital archive ● Site Matrices and Grouping and Phasing information ● Multiple forms and mixed explicit data What sort of Information is (re)useful to others?
- 6. The Process of Analysis: Stratigraphic Correlation We rarely describe how we go about this. Summarise Descriptive Information e.g. Code by soil types/inclusions. Correlate Horizontally e.g. Construction/Occupation/ Destruction. Commonly below another. Consider linkage strengths. (etc.) Correlate Vertically e.g. New activity? Block together common activities. Higher-Order Interpretations Noting rationale (again based upon physical, stragitgraphic & spatial considerations). Plot Spatially Revisit the plans (or GIS). This may strengthen/deny previous reasoning (if latter, reiterate). We often assume that the most certain interpretations exist at the start of stratigraphic analysis and become less so ‘higher up’. The opposite can be true.
- 7. The Process of Analysis: Stratigraphic Grouping ● The ‘grouping process’ tries to understand how lowest order, individual actions can make up an activity. ○ The latter may have no exact chronological implications - activities can be quick or can last centuries. ○ Whatever form groups take, not all stratigraphic units will belong to any one with equal certainty. Section through Çatalhöyük's Building 5 that the highlights the need for grouping of features. Note the difference in complexity between a post retrieval pit and a platform (with associated burials) and remodelling events that are represented by the steps in the platform (highlighted with arrows), and which are often grouped (as in this example) as the same feature
- 8. The Process of Analysis: Higher Temporalities Periodisation ● If groups make up periods (defined as site-wide activities [?]), then the number of such periods will vary depending on how big an exposure is being analysed. ○ e.g. in the whole of London, only 3 big fires would form periods (and even that does not work across all sites - as at Çatalhöyük). Knowing when something is thought to be site wide, and when it is not, matters - scale of correlation Plan and section of Çatalhöyük showing the shifting pattern of occupation in the excavated area, as interpreted by Mellaart in 1967
- 9. Space and Time Aim for ‘land-use’ diagrams e.g. Carthage Certainty Representing different degrees of certainty of linkage (was one layer, exactly contemporary, broadly contemporary) Duration of Processes Stretch boxes to represents events vs. processes vs. gaps Representing more than just sequence.
- 10. Example of Çatalhöyük Konya Region Turkey Neolithic and Chalcolithic ‘Tell Site’. Occupied for approximately 2200 years, from c.7500-5700BC. Covers approximately 33.5 acres and 20m deep stratigraphic sequence. Only c.4% of the Neolithic mound excavated. Presents some interesting spatiotemporal challenges
- 11. Example of Çatalhöyük: Principles (Temporal Units) Basic Stratigraphic Unit A unit, equivalent to a ‘context’ in British field archaeology, represents the basic recording element.assigned a unique identifying number and is recorded on a Unit Sheet. Unit ● Ideally a single identifiable depositional event. ● Some units may represent multiple depositional events that it is impossible to excavate separately ● Some depositional events may be subdivided into multiple units. Higher Order Spatial Grouping A feature represents a group of related units recorded on a Feature Sheet. These are hybrid stratigraphic groups. Feature ● Not all units need belong to features. ● Assigned to any group of related units that need to be described ● Or because the existence of a feature number is helpful when referring to the entity ● Feature system is fluid, potentially including any conceivable group of units Higher Order Temporal Grouping Phasing of units relates to the occupation sequence of a building or external area, as illustrated in the Harris matrix for each building* and space*. *Separate spatial groupings. Phase ● Recorded on the Space sheets as ‘occupation phases’ ● Represent major changes in the life history of a building or space while subphases indicate minor changes. Highest Order Temporal Grouping Level ● Typical of old school ‘Tell’ Site methodology ● Problematic because Tells are neat temporally neat. A level is a group of one or more spaces of buildings that are at least partially contemporary with one another. Inhereited and modified from James Mellaart 1960’s division of the area he excavated into 15 successive building ‘levels’ from 0 to XIII.
- 12. Example of Çatalhöyük: Practice (Matrix Notation) Phases: horizontal line through the matrix Units: standard stratigraphic matrix cell Features: nested brackets around units All these elements, as well as the spatial groupings of Space and Building are reflected in the relational data structure of the project database.
- 13. Example of Çatalhöyük: Common Spatiotemporal Issues
- 14. Example of Çatalhöyük: Common Spatiotemporal Issues
- 15. Example of Çatalhöyük: Visualising Spatiotemporality Animation showing spatial distribution of obsidian projectile density through time in Çatalhöyük Buildings 65 & 56, alongside cumulative distribution.
- 16. Modeling the Matrix Example: Silbury Hill
- 17. Allen - Temporal Operators Relation Inverse Before (precedes) < After (preceded by) > Meets m Met by mi Overlaps o Overlapped by oi During d Contains di Starts s Started by si Finishes f Finished by fi Equals = Allen Operators (Allen 1983): temporal relation classifications that acknowledge the implicit spatiotemporality of stratigraphic relationships in Harris (e.g. Superposition) along with other less explicit temporality seen in other archaeological records. Modeling the Matrix
- 18. Modeling the 4D nature of Phase/Period Potentials of a semantic approach to stratigraphic analysis Search and analysis of associated finds and samples using extra temporal relations Presenting outputs and re-use of data enhanced for temporal cross search Fig4. temporal relations on spatiotemporal volumes A and B
- 19. Modeling the Matrix “The problem of representing temporal knowledge and temporal reasoning arises in a wide range of disciplines including computer science, philosophy, psychology, and linguistics. In computer science, it is a core problem of information systems, program verification, artificial intelligence, and other areas involving process modeling” (Allen 1983, 832) (Image: Binding 2011, 14) STAR Semantic Query Browser Implicit temporal relationships in the diagrams that are not formalized in the digital records
- 20. Bayesian chronological modeling One difference between a Bayesian chronological model and an archaeological sequence diagram is that the Bayesian chronological model may include relationships that cannot be expressed by simple before/after stratigraphy. The illustration recognizes three possible relationships between two chronological phases where one is older than the other (Fig. 7). Only two of these relationships can be represented stratigraphically. Overlaps in Time relationship Meets in Time relationship A Bayesian chronological model comprises directly-dated events and the start and end dates of one or more chronological phases. The start and end dates of a chronological phase typically map directly to an archaeological context “One chronological phase can be older than the other such that the end date for the older chronological phase is the same age as the start date for the younger chronological phase (Fig. 7, middle)”. Dye & Buck 2015 Fig. 7.
- 21. Would Process Modeling for Analysis activities help? Identify common steps in the Analysis process Identify and clarify differing approaches to process Enable semantic mappings between common concepts and terms used in Analysis process(es)
- 22. Towards a Clearer Spatiotemporality Our Goals Querying, Re-Use & Interoperability: ● Ease of use by stratigraphers. Analytical tools: ● Deeper spatiotemporal understanding and interpretation by stratigraphers and other specialists Visualisation: ● Work towards a clearer way of presenting spatiotemporality. Dissemination: ● Consideration of wider audiences for publication (specialists and academics both inside and outside of the project, students, or wider audience with an interest in understanding spatiotemporal processes of archaeology. Visualisation & Dissemination Query & Analysis
- 23. Conclusions: Representation of other Allen relationships 04 ● To get at increased spatiotemporal nuance and complexity ● To enable more complex analysis and interpretation Development of new modes of spatiotemporal visualisation 03 ● Highlighting complexity of spatiotemporal relationships ● To facilitate understanding and communication Standards of expression of spatiotemporal relations 02 ● Practically derived from existing processes (eg. Harris Matrix) to facilitate ease of use and re-use 01 ● At the level of data structure (ie. CSV as opposed to images ● To facilitate re-use Consistent standards for digital stratigraphic recording
- 24. ● Allen, J.F. (1983) 'Maintaining Knowledge about Temporal Intervals'. Communications of the ACM 26, 11, 832-843. ● Harris, E.C. (1979) Principles of Archaeological Stratigraphy (1st Edition). London: Academic Press. ● Rains, M. (2000) 'Review of ArchEd and Stratigraph - Excavation recording and analysis software[Software]', Internet Archaeology 8. https://doi.org/10.11141/ia.8.9 ● Roskams, S. (2001) Excavation. Cambridge: Cambridge University Press. ● Taylor, J.S. (2016) Making Time For Space At Çatalhöyük: GIS as a tool for exploring intra-site spatiotemporality within complex stratigraphic sequences. PhD thesis, University of York. ● Tudhope, D. et al. (2011) 'Connecting Archaeological Data and Grey Literature via Semantic Cross Search', Internet Archaeology 30. https://doi.org/10.11141/ia.30.5 ● Papadakis, M., Doerr, M. and Plexousakis, D. "Fuzzy times on space-time volumes," eChallenges e-2014 Conference Proceedings, Belfast, 2014, pp. 1-11. ● Dye, T.S. & Buck, C.E. (2015) Archaeological sequence diagrams and Bayesian chronological models.Journal of Archaeological Science, 63. 84 - 93. ISSN 0305-4403 ● Farid, S. & Hodder, I. (2014) 'Excavation, Recording and Sampling Methodologies.', in I. Hodder (ed) Çatalhöyük Excavations: The 2000-2008 seasons., 35-52. Los Angeles: British Institute at Ankara & The Cotsen Institute of Archaeology, UCLA. References
Editor's Notes
- KEITH. Introduction of Authors.
- Various solutions exist for producing matrices digitally, ranging from: Earlier software packages sucha s Bonn Matrix, Stratify, ArchEd. Replicating drawing them in software, like Excel, Or, relational DBMS solutions (MS Access, etc.) To niche, and small scale specialised software, like the HM Composer. Getting data out of these matrices into digital archives or sharing and cross-searching data from such matrices is what we are addressing in this paper.
- 1979 - Harris defines principles of stratigraphy which are still essentially deployed today - virtually unchanged He asserts that there are three main areas of stratigraphic study of interest to the archaelogist: Theories and laws – e.g. Law of Superposition Recording practices Post-excavation analysis practices In this talk we are mostly concerned with the lattermost.
- Previous research on projects (ref to STAR, CIDOC, etc in later slaides, depending upon available time in presentation) have developed tools for interrogating context level data through stratigraphic relationships and related temporal and spatial relationships. But has encountered the following issues: • Limited consistency in how stratigraphic data is held in digital archives – if at all – problems with just scanned images of matrix (e.g. PDF scans). • Even less for Phasing data [KM1] – although phasing and grouping relationships may be written in the free-text reports or books • Problems encountered with representing Phasing relationships to Groups and Contexts that enables sensible data re-use. [KM1]“Turning next to data manipulation after excavation, there is a great need to sort out the concepts used in stratigraphic analysis … to match the systematization which has been developed in the production of the site record. For the most part what is needed is intellectual clarity in defining concepts and then labelling them”– Roskams (2001) p278-279
- How integral is the matrix to bringing together other elements of the archives? The spatio-temporal matrix and associated physical grouping and temporal phasing relationships should be the means to navigate archaeological records to associated Finds, Environmental, Dating and other site records asociated through the stratigraphic record. Importance of consistent representation of the data and relationships to enable others to re-use the data from your archives in the future as a basis for new or extended archaeological investigations and research.
- JAMES (SPR) Make explicit the off-site practice how are these sorts of groups structured. But this can be difficult to get to – there are various conventions and ways in which things are grouped (temporal - phases, levels or potentially more spatio-functional - strat. groups, features - each group type is an interpretative process – which may or may not begin in or out of the field).
- JAMES (SPR) Each different type of group is an abstraction of some sort of physical spatiotemporal concept, that inherits the stratigraphc relationships of the underlying matrix (i.e.can be constructed as a group matrix). However, this has specific implications for increase complexity of the spatio-temporal relationships at the group level as they might be defined in terms of Allen Operators for instance – i.e. the more they are grouped the more potential for more nuanced and complex spatiotemporality
- JAMES (SPR) Thesis: Qualitatively the mathematics of the matrix is not as important as the interpretation of that matrix as a group or phase. Modeling this is perhaps the more straightforward part of the process. Would be good to explore the ways in which higher order grouping and phasing is achieved, what the rationale behind it and the commonalities of practice so that it might be effectively modelled and perhaps reused.
- (SPR) Note that looking at these issues isn’t a new thing and refer to Steves examples… Not new - lots of attempts to look at duration, certainty of correlation and spatiotemporality through land use diagrams. These kinds of representations acknowledge that we need to find ways to acknowledge that our correlations can be weak and strong, and that archaeological strata have complex temporalities - they are not just events, but processes.
- This needs to be visible.
- You can make stratigraphy drive spatiotemporal visualisations. So there is potential for reuse and analysis.
- KEITH. Potential benefits if the stratigraphic records, including groups/phases were more consistently recorded in archive data. • Potential of more explicit Phasing data methodology approaches • Semantic opportunities of using Allen operators[KM1] to cross-search related data • Semantic search and e.g. for dated material - Bayesian potential enhanced by additional dating parameters from additional temporal relationships. [KM1]Slide of Silbury Hill matrix with Allen operators would work here
- Potential to use the Spatio-temporality to semantically search at a higher level of granularity across Periods – e.g types of finds from certain stratigraphic units such as “Iron Age” pits across many different sites. ‘Query-ability’, Deeper Analysis, More nuanced narratives, Advanced temporal visualisation. Re-use pottential,
- Experiences derived from the STAR project (ref Tudhope et al) suggest that the application of RDF technologies and Linked Open Data (LOD) for expressing and semantically interrogating graph database relationships, based on ontological modelling of stratigraphic spatio-temporal relations and more explicit use of broader temporal relationships, could help improve the relative sequencing and phasing process in stratigraphic analysis. As a further benefit it could help to provide a basis for much needed improvements to stratigraphic analysis records and data sharing (cf Roskams quote) and a more information rich archival structure and digital preservation format.
- Ref. Dye & Buck 2015 paper James Note - that this is something we are actively doing at Catalhoyuk too.
- This is an open question to the audience and other practitioners. Something we hope to explore further in research work in the future.
- JAMES Ultimately we seek to start a discussion with the following goals in mind...
- · There is a need for more consistent standards for digital records of Stratigraphic relationships if matrix data is to be re-used effectively. · – at a mundane level e.g. CSV - Not just PDF images of matrix diagrams. · There needs to be development of standard approaches for more explicit ways of expressing temporal and spatio-temporal relations within archaeological records. · Practically, the more these could be derived explicitly from the processes that already exist for data recording (e.g. Harris matrix) the more likely to succeed and be (re)used. · Ideally the processes of grouping and phasing would also benefit from new ways to visualise the complexity of the temporal and spatio-temporal relations, thereby extending and improving the use of Harris matrices for stratigraphic analysis. · Representing explicitly other Allen relationships, would also help in conceptualising and explicitly sharing greater understanding of the temporal relationships that are currently only implicitly recorded in our matrix records.