Slieve Thoul, also known as Saggart Hill, lies at the north-westernmost extremity of the Dublin-Wicklow mountains. It is 396 metres high and lies close to where the boundaries of counties Kildare, Wicklow and Dublin meet. Slieve Thoul is formed of sandstone, siltstone and shale bedrock which are characteristic of the western foothills of the Dublin-Wicklow Mountains. The area to the south and east of Slieve Thoul around Brittas is notable for its distinctive topography of low hills, mounds and hummocks. This is known as the Brittas Gravel Complex and includes sands and gravels deposited at the end of the last Ice Age. The deposits were laid down as glaciers on the Wicklow Mountains melted and retreated. Moraines, meltwater channels and glacial fans are evident in the area, as well as scalloped landscapes which were scoured by retreating ice. Coolmine Hill, on which Lugg Woods is situated, is to the north east and is 327 metres high. The forested areas of Slieve Thoul and Lugg Wood consist principally of plantations of spruce and larch. The Slade Valley, also known as the Slade of Saggart, is to the east of Lugg Woods. This is a glaciated valley through which the Camac River flows. Slade is a name given to a steep ravine or valley. 



Slieve Thoul takes its name from the Irish Sliabh Toll, meaning ‘The Mountain of the Hollow’. The mountain is crowned with two Neolithic passage tombs that date to around 3,500–3,300 BC. These tombs were great mounds of stone and earth, with a stone-lined passageway that led to a burial chamber. The most famous example of a passage tomb in Ireland is the great monument at Newgrange in the Boyne Valley. At least 11 of these monuments are known to crown the summit of peaks in the Dublin Mountains, forming an extended upland cemetery that stretches into the Wicklow Mountains.  




The passage tombs on Slieve Thoul are part of a wider complex of tombs on the summits of the hills and mountains of Dublin and Wicklow, with over twenty such monuments concentrated in this area.  The passage tombs on Slieve Thoul are the most north-westerly of this group of tombs. Tallaght Hill to the east and Seahan Mountain to the south-east are the closest tombs to Slieve Thoul.

The Ordnance Survey letters from the 1830s state that “…the two Cairns of Sliabh Toghail are open. The largest of them was very large and high and was opened within the last fifteen years. It contained a large grave, covered by a very large flag stone, which was broken and carried away, but the supports still remain, though not in their proper places”.

Link to Slievethoul & Lugg Recreation Site Details and Map.


Text and photos: Abarta Heritage



Useful Resources

National Monuments Service

NMS Historic Environment Viewer

South Dublin Libraries Local Studies Resources

South Dublin Historical Mapping

South Dublin County History

South Dublin Libraries SOURCE  - a digital archive of local studies material relating to South Dublin County


[last updated: 24.07.20]

Archaeology Sites in the Dublin Mountains

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