Getting to the Core of the Problem: Petrological Results from the Irish Stone Axe Project
Cooney, Gabriel, Mandal, Stephen, Antiquity
When a distribution map of Neolithic stone axes in Ireland was puplished in Antiquity (Grogan & Cooney 1990), the new Irish Stone Project (ISAP) was mentioned. Stone axes, it turns out, are unusually common in Ireland. Here Project progress is outlined, with special attention being given to those axes identified as having been moved across the Irish Sea.
Irish stone axe studies
Since 1991, the Irish Stone Axe Project (ISAP) has been carrying out a comprehensive archaeological and petrological study of Irish stone axes (with substantial funding from the National Heritage Council). The aim is to establish a data-base of Irish stone axes incorporating contextual, morphological and petrological information, as the basis for further research on production, distribution and deposition. The development and potential of stone-axe studies in Ireland is detailed in Sheridan et al. (1992) The Project has produced lists and distribution maps for Cos. Tipperary and Louth (Cooney et al. 1990; b), and a first report on petrological research to the end of 1992 (Mandal et al. 1991/2); a second petrological report covering work until mid 1994 is in press (Mandal a Cooney in press), and a more general review in preparation (Cooney forthcoming). Two general accounts of ISAP work are Cooney 1992; 1995).
In 1990 the preliminary known total of axes from Ireland was c. 10,500 (Cooney & Grogan 1990: 559). Subsequent ISAP work on the major museum collections in the National Museum of Ireland (NMI-Dublin) and the Ulster Museum (UM-Belfast) and on other collections has shown that there are at least 18,000 stone axes with an Irish provenance. Comparison with the estimate of 4000 axes from Scotland (Sheridan 1992: 195) and 2200 for Wales and the mid west of England (Darvill 1989): 30) indicates a density of finds in Ireland over three times greater than in Wales and four times greater than in Scotland (Figure 1). In this paper we set out some recent petrological research, in particular the recognition of stone axes which appear to have originated outside ireland and whose importation and presence indicate networks of contact and acquisition.
Surface petrological identification
In the petrological investigation, a two-phase strategy of research is used. An initial surface examination with a hand lens determines the rock type and recognizes axes of similar lithologies. Detailed analysis of a selected sample chosen from surface examination uses microscopic and geochemical techniques (below). The petrological results are combined with archaeological data concerning morphology, function and distribution.
A total of 13,568 stone axes (as of January 1995) have been surface-examined and grouped by lithology (Figure 2). Research to date has concentrated on the major collections in the NMI and the UM. The grouping by rock type using surface-examination is a guideline for microscopic research. Axes of similar lithology grouped on the basis of surface examination do not necessarily come from the same or only one source - although this can be the case as with porcellanite axes which are identifiable in the hand. There is a clear contrast then between the Irish groups, and the Groups (known by Roman numeral) used in Britain to define axes coming from known or restricted sources (see Clough &, Cummins 1979; 1988 for these, developed by the Sub-Committee of the South-Western Group of Museums and Art Galleries on the Petrological Identification of Axes and subsequently by the Council for British Archaeology Implement Petrology Committee (CBA IPC)).
The most striking result from surface examination has been the dominance of porcellanite as source material for axes. Two sources are known where porcellanite outcrop was worked to produce stone axes, both in Co. Antrim: at Tievebulliagh, and at Brockley on Rathlin Is land off the north coast of Ireland (see Jope 1952; Sheridan 1986; Mallory 1990. …