2019:246 - Carrowmore, Sligo

This monument is located in the heart of Carrowmore passage tomb cemetery and has been recorded on the Sites and Monuments Record as a Barrow (unclassified). The site was subject to a two-week IT Sligo archaeology student training excavation. The excavation had two key aims: to establish the date and nature of the monument, and to assess how it relates to the surrounding megalithic complex. 

Prior to this project, the monument had received little or no antiquarian or archaeological attention. Burenhult (1980, 93) recorded it as ‘Structure 8’ during his excavation campaigns of the 1970s, but did not classify it as a barrow. Timoney (1984, 321-4) recorded it as ‘No. 13: Carrowmore II’ and described it as a ‘badly mutilated barrow’, suggesting it may be a ring-barrow or a ‘bowl-barrow of the ditched variety’. The monument is also absent from most cartographic sources: it is not indicated on George Petrie’s 1837 draft Ordnance Survey map of Carrowmore, and does not feature on the First Edition Ordnance Survey map. Both maps, however, indicate a field boundary running immediately outside the northern edge of the monument, crossing the existing field on an east-west axis and connecting with a north-south aligned boundary. This field boundary, which is no longer present, was mapped as a zone of low resistance by an earth resistance survey. The monument is represented on the Historic 25 inch OS map (1890-1915) as a circle of 23 stones measuring 21m north-south x 19m. This is clearly an error and it appears that the monument was confused with the megalithic tombs in the immediate environs. The same error is replicated on the 1940 Cassini Ordnance Survey map, with the annotation ‘Stone Circle, site of’. 
   
The monument is constructed at the very southern terminus of a natural gravel ridge that snakes east-west through Carrowmore. One trench (18m x 2m) was opened across the eastern side of the barrow where the monument is best preserved, capturing part of the central sunken area, the ditch, and anomalies located outside the ditch to the east that were only visible in an earth resistance survey. The trench sampled approximately 10% of the overall area of the monument (0.026ha). De-sodding was by hand, after which the surface of the trench was subjected to a preliminary metal detector survey; metal hits were marked by plastic pegs (Detection Device Licence R000498).  The trench was excavated stratigraphically using the single context system; 41 contexts were recorded. A system of 100% sieving was employed whereby all excavated deposits (including topsoil and disturbed plough-zone material) were dry sieved through 5mm mesh sieves. All sieved spoil was assessed with a metal detector to confirm the absence of metal. Fourteen soil samples were taken and subsequently sieved under laboratory conditions at IT Sligo. 

The excavation trench to the east of, and external to, the ditch of the monument revealed a series of natural sterile geological layers. Three linear cut features – probably two plough furrows and a field boundary – truncated the uppermost natural sterile stratum. All three ran parallel to one another and were orientated north-south. The most substantial of these, the probable field boundary, was consistent with a low resistance anomaly identified during a 2016 earth resistance survey of the site, and is interpreted as part of a possible rectilinear enclosing feature. It was 2.4m wide, 0.38m deep, and a circular post-hole (0.45m diameter x 0.38m deep) was located within it. The area outside the monument was sealed by a heavily disturbed stratum that produced approximately 200 finds of late 18th-, 19th- and 20th-century date, including pottery sherds, glass shards, clay pipe fragments, roof slate, iron fragments, plastic etc. This material appears to have originated from a farmhouse dung-heap that was spread as fertiliser on the field around the monument. There was a distinct paucity of post-medieval and modern finds from within the monument, suggesting a folk belief, respect for, and avoidance of the monument itself (as is frequently observed with ringforts).
 
The enclosing ditch of the monument was visible prior to excavation as a circular depression varying from 2-3m in width and enclosing an internal area of 15.1m north-south x 16.2m. Excavation revealed the ditch cut to be 2.9m wide at top, 1m wide at base, but just 0.8m in depth. The ditch was not fully excavated due to time constraints. The earliest fill comprised a layer of angular stones that was particularly compact on the north-eastern side of the ditch, almost like packing or revetment material, but were less concentrated on the western side of the ditch. A series of fills overlay this, several of which produced post-medieval finds together with prehistoric lithics, indicating disturbance.

The ditch enclosed a relatively flat area which surrounded a broad concentric band (c. 8m in diameter) of multiple overlapping layers of stones and cherty gravels that sloped inwards into a central depression. Several of the stone layers, particularly towards the centre of the monument, occurred within a matrix of charcoal-rich silts. The eastern limit of the band of stone was clearly delimited by a line of 17 large stones set in a cherty gravel matrix. A roughly oval setting of 20 stones (1.45m north-south x 0.45m) rested on the surface of the stoney band, protruded through the sod and were visible prior to excavation. This stone setting delimited the central sunken area of the monument, which may be as little as 1-2m in diameter.

An assemblage of 35 lithics was discovered during excavation, some in secure archaeological contexts within the monument, and others ex situ in the ploughzone. Lithic specialist Cian Hogan identified 5 cores, 21 pieces of debitage, 7 convex scrapers, 1 concave scraper and 1 retouched piece. Chert was the dominant raw material, but worked quartz and flint were also present. The varying condition of the assemblage, amongst other factors, demonstrated that this assemblage related to several different time periods and events. 
  
One of the lower layers of stone within the central band of stone was dated by OSL to the Middle Neolithic. The excavation established that the monument is not a late prehistoric barrow, as was previously believed, but the nature of the monument can only be ascertained by further excavation. 

References:
Burenhult, G. 1980. 'The archaeological excavation at Carrowmore, Co. Sligo Ireland. Excavation seasons 1977-79.' Theses and Papers on North-European Archaeology 9.
Stockholm, Institute of Archaeology. 
 
Timoney, M.A. 1984. 'Earthen burial sites on the Carrowmore peninsula, Co. Sligo.' In:
G. Burenhult (ed.) The archaeology of Carrowmore. Environmental archaeology and the megalithic tradition at Carrowmore, Co. Sligo, Ireland. Theses and Papers on North-European Archaeology 14, 319-325. Stockholm, Institute of Archaeology.

School of Science, IT Sligo