Dating Mechanisms Possibilities and limitations of dealing with time intervals of the Roman Limes. Vagueness in the case of terra sigillata (Samian) chronology.
Creators: name: Mees, Allard W.
name: Thiery, Florian
Publisher: name: Zenodo
Year: 2021
Subjects: Linked Data
Relative Chronology

description: <strong>Introduction</strong> The development of the Roman Limes has always been thought to have been a corner-stone in establishing chronologies of various finds-groups in archaeology. The consecutive construction of Limes sections, each time deeper into enemy territory, should theoretically provide a solid framework for dating artefacts found at the individual military camps in each segment, but the precise chronological time intervals of the occupation phases has remained until now very sketchy. Thus finds from Limes sections have been widely used to date the same sort of finds found elsewhere which do not have dated contexts. However, since there are only very few historical dates attached to the Limes sections, many military camps on the Limes have only been dated by comparing material from the few dated military Limes camps, which causes a circular reasoning. The time intervals of Limes sections such as those of `Hadrian’s Wall` or the German Wetterau-Limes are thus suffering from temporal vagueness within the underlying dating mechanisms and a lack of absolute dates. In order to generate knowledge about the underlying processes of dealing with vagueness in these time intervals, visualisation of the underlying reasoning process is required in order to outline the dimension of the temporal vagueness involved. The increasing usage of semantics and graph technologies in the digital humanities offers methodologies to tackle these complicated archaeological issues. Low-threshold online available tools dealing with semantic based methods and algorithms could help the scientific community to explore the possibilities of these emerging techniques. <strong>Methods and Materials</strong> In order to handle the problem of solving and visualising vagueness within the sequences of relative dating intervals, we use the following methods: first we start with a 3D distance calculation of given Correspondence Analysis (CA) results, in which the quantitative relations between finds and proposed time intervals are set out. Following the `horseshoe paradigm`, the calculated distances of the presumed time intervals provide us with a measure of overlap between the intervals. After that, our `Alligator Algorithm` will be applied. This method calculates and fixes datable and non-datable (floating) periods, by finding the next 3D CA neighbours. The intermediate result of fixed and floating time intervals are then stored as `virtual fuzzy years`. This enables us to establish a relative chronology based on Allen’s interval algebra. Any `virtual fuzzy year` resulting from that is then transformed into relative `Allen time intervals` (‘later then’, ‘overlaps with’ etc.) and stored in Resource Description Format (RDF) structures to visualise the results. A second method is applied by using the Academic Meta Tool (AMT). This tool allows for deployment of temporal reasoning including statements about the vagueness. In this case, we use the `Allen time interval` results and calculate the degree of connection between the periods (vagueness). From there, an AMT ontology is developed which consists of the implemented reasoning methods to establish the chronological vagueness within and between the periods involved. The reasoning results are stored in graph structures like RDF to visualise the results. This study uses the online available database `Samian Research`, based on the `Names on Terra Sigillata` project of Leeds and Reading Universities funded by the AHRC and the RGZM at Mainz (RGZM 2021). The database comprises a quarter of a million potters’ stamps on Terra Sigillata, recorded from dated and non-dated sites from all over the Roman Empire. Since the same South Gaulish potters’ stamps may occur on different sections of the Limes in different parts of Europe, this material allows a) for comparison and b) for temporal reasoning between the Limes sections of the 1st and 2nd century AD. <strong>Results</strong> The `Alligator Algorithm` and `AMT Algorithm` employ online software solutions based on Linked Data and semantic technologies, JavaScript, JAVA and a RDF4J triplestore. As a result, the little minions `Alligator` (Thiery and Mees 2019) and `Academic Meta Tool` (Unold and Thiery 2017) have been implemented on an operational level. In combination as a `linked pipe`, they are able to make the mechanisms of Limes-dating based on specific material find-categories more comprehensible. `Alligator` was developed by the department of Scientific IT at the RGZM, AMT is a joint project between i3mainz and RGZM within the mainzed network. As an example, with the help of this new tool `Alligator`, it is possible to analyse and visualise the dependencies within the dating arguments of individual Limes sections when using Terra Sigillata data. `Virtual timelines` may show the position of the `Main-Limes` and the `Odenwald-Limes` in `virtual absolute years` as a fundament for a relative Limes chronology. With the help of AMT, temporal reasoning with vague connections is possible. The output formatted as RDF, Linked (Open) Data and other graph formats, enables interoperability and reusability to establish reproducible research as a basis for Open Science. The tools presented are enabling archaeological statements about the chronological sequences of different Limes sections. Some German Limes sections are apparently to be dated considerably later than thought hitherto, whereas others seem to be less reliably dated. This research also pushes forward the question whether the supply of the identical group of find-material was identical in all parts of the Limes sections involved. <strong>Discussion</strong> The implication of this methodological breakthrough for dating time intervals of Limes sections with Terra Sigillata using Allen’s reasoning algorithm is clear: Terra Sigillata is in archaeology apparently highly overestimated in its absolute dating capability. Whereas the establishing of relative chronologies can - due to the huge amount of material involved in the analysis - be considered as solid and stable, establishing exact starting and / or end dates of Limes parts is clearly beyond the dating capacities of this find category. This new method of dealing with uncertain time intervals opens possibilities for comparisons with other timeline oriented methods used to date Limes sites such as with coin dates. It also offers opportunities to handle stylistically defined ceramic periods in prehistory with similar vague timelines in combination with C14 dates. <strong>References</strong> RGZM. 2021. ‘Samian Research’. 2021. http://www.rgzm.de/samian. Thiery, Florian, and Allard Mees. 2019. alligator - Allen Transformer (Version v0.1). Zenodo. https://doi.org/10.5281/zenodo.2540709. Unold, Martin, and Florian Thiery. 2017. ‘Github Academic Meta Tool’. 3 November 2017. https://github.com/search?q=topic%3Aacademicmetatool+org%3Amainzed.