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AFrican red slip ware discovered in Ireland : an exploration of archaeological deposition and provenance using Laser Raman Spectroscopy (LRS) and automated SEM-EDS analysis (QEMSCAN®).

This project is a collaborative study conducted by Professor Martin Feely, Head of Earth and Ocean Sciences in the School of Natural Sciences and Dr Amanda Kelly, lecturer in Classics in the School of Languages, Literatures and Cultures at NUI Galway.

http://www.nuigalway.ie/eos/staff/academic_staff/feely_m/feely_m.html

http://www.nuigalway.ie/classics/kelly/

This research was prompted by the identification of a rimsherd of African Red Slip Ware (henceforward ARSW) at the site of a ring ditch at Kilree 3, in Co. Kilkenny, by Dr Amanda Kelly (the site was originally excavated by Patricia Lynch in collaboration with Irish Archaeological Consultancy Ltd on behalf of the National Roads Authority. The National Museum of Ireland granted permission to study the sherd).

North African Red Slip Ware is the name given to a number of related ceramic profiles in fineware fabrics which were manufactured throughout the area of modern Tunisia from the late 1st to the 7th century AD. The sherd’s initial classification as ARSW Form 91C was reliant on its distinctive profile representing the classic African flanged bowl which were produced in northern Tunisia (combined with initial general fabric observations made by Dr. Kelly with a 30x microscope). The form first ascribed to the Kilree sherd constitutes a late form in the lengthy production series of ARSW, where this sherd would date to the 6th century AD.

              

Distributions of African Red Slip Ware are extensive and stretch throughout the Mediterranean from Antioch through to Conimbriga. Campbell, building on Thomas’ research, cites ten sites in Britain where the ware has been found but its presence in Ireland has gone completely undetected. The sherd represents the first identified ARSW found in Ireland; representing a depositional context far from its source of production, lying beyond any regularized trading patterns for this series of ceramics.

The sherd was discovered in an archaeological feature within a ring-ditched enclosure where it was associated with a suite of metal artefacts of Irish manufacture. Moreover, it represents a ceramic import on an island which has no tradition of ceramic manufacture in this period.

In 1998 Michael Mackensen astutely observed that although John Hayes (who established the first typological sequence for Late Roman finewares) had noted that distinctive form-groups could be correlated with distinctive fabrics, he had fallen short of fabric classifications, preferring to classify in terms of form and decoration.

The now-established correlation between form and fabric, indicates that evidence relating to the exact pottery factory which produced the Kilree 3 sherd is contained within the fabric of the sherd itself. With this in mind, Professor Martin Feely (Earth and Ocean Sciences) had a polished thin section (~100 microns thick) of the slip prepared in the rock preparation laboratory at NUIG (see fig A). He conducted two detailed mineralogical studies, using Laser Raman Spectroscopy (LRS) and automated scanning electron microscope linked with energy dispersive spectrometry (SEM-EDS) analysis (QEMSCAN®), in order to complement the emerging narrative prompted by the discovery.

The Laser Raman Spectroscopy (LRS) was conducted by Edward Lynch at NUI, Galway (NUIG) using a Horiba LabRam II spectrometer. The instrument is equipped with a 600 groove.mm^-1 diffraction grating, confocal optics, a Peltier-cooled CCD detector (255 by 1024 pixel array at -67°C) and an Olympus BX41 microscope arranged in 180° backscatter geometry. Sample excitation was performed using a Ventus diode-pumped, continuous wavelength, 532 nm laser with a maximum power output of 50 mW. Raman analysis was carried out using a 100x microscope objective (0.9) resulting in a laser spot size of ~ 2 µm. Excitation power at the sample typically ranged between 10 and 20 mW.

The QEMSCAN® analysis was conducted at the Camborne School of Mines (CSM), University of Exeter, UK, using a QEMSCAN® 4300 system. This system utilises a Zeiss EVO 50 series SEM consisting of four light element Bruker SDD (Silicon Drift Droplet) Energy Dispersive X-ray Spectrometers and an electron back backscattered detector. Sample measurement design, data processing and database development was completed by Dr Gavyn Rollinson at the CSM. (see figures 1 and 2).

These in-depth mineralogical analyses will be published jointly in a journal of archaeological science to allow for further comparative studies within the growing corpus of fabric studies and, ultimately, with a view to securing a source of production for the sherd in Tunisia. Moreover, the studies were conducted as a pilot with a view to analysing a wider sample of imported pottery discovered on sites in Ireland.

A second paper will address the archaeological narrative pertaining to the sherd which is in many ways unique in terms of findspot in Ireland, distance between production and deposition and artefact type (as Ireland was an aceramic culture in this period with the later hand-made locally-produced Souterrain Wares constituting a poor substitute). This research grapples with the difficulty in interpreting this identifiable, but singular, North African sherd found in a deposit containing other artifacts of Irish manufacture.

What circumstances led to the deposition of a broken bowl from North Africa at a land-locked site seemingly off the beaten trading track? It is hoped to build upon recent research on Mediterranean ceramics that found their way to the island of Ireland in the 5th and 6th centuries AD with a view to presenting this newly-discovered sherd against a backdrop of long-distance exchange and hopefully painting a more integrated portrait of Ireland at this pivotal watershed in the island’s development.

For more information on Mediterranean wares discovered in Early Medieval archaeological contexts in Ireland see:

Kelly, A. 2010 The Discovery of Phocaean Red Slip Ware (PRSW) Form 3 and Bii ware (LR1 amphorae) on sites in Ireland - an analysis within a broader framework. Proceedings of the Royal Irish Academy 110C, 35-88.

http://www.ria.ie/Publications/Journals/PRIA-Section-C/Online-access/110C-(2010).aspx

Kelly, A. 2010 An African Red Slip Sherd From Kilree 3, Co. Kilkenny (AR093, E3643) (N9/N10 Rathclogh to Powerstown). Unpublished report prepared on behalf of Irish Archaeological Consultancy Ltd. for the National Roads Authority.

Kelly, A. 2009  Imported Pottery (PRSW/ Bii ware): APPENDIX 10a.  In R. O’Hara 2009 Report on the Archaeological Excavation of Collierstown 1, Co. Meath. A008/015, E3068. Final Report. M3 Clonee–Kells Motorway Collierstown 1. Contract 2 Dunshaughlin-Navan. Report prepared on behalf of ACS Ltd. for the National Roads Authority.

http://www.m3motorway.ie/Archaeology/Section2/Collierstown1/file,16721,en.pdf

Kelly, A. 2008 Mediterranean Pottery on the M3: a Turkish Import in County Meath. Seanda - NRA Archaeology Magazine 3, 16-18.

http://www.m3motorway.ie/Publications/file,16033,en.pdf

    

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