The results of a masonry analysis of the majority of Irish pre-Romanesque churches

are presented. A number of local styles are identified in high-density areas, mostly

in the west of the country and it is shown that the differences between these styles

were not determined by geology. It is argued that these styles represent habitual

variation and are therefore indicative of local groups of masons working over a relatively

short period of time. This assessment is supported by an analysis of stone

supply that suggests that quarrying was organised in an ad hoc manner to supply

local needs. These churches are normally placed within a broad timeframe spanning

the tenth to early-twelfth centuries but a number of factors combine to suggest

that the habitual styles are a relatively late development, perhaps mainly from the

mid-eleventh century onwards. Some of the implications of this proposed refinement

of the existing chronology are briefly discussed.