Thursday, 8 August 2013

Elagh Castle - geophys & trench locations

The August excavation at Elagh Castle follows-on from work undertaken by the CAF earlier this year on behalf of the NIEA - a geophysical survey (February) and an evaluative excavation (March).

The results of the survey have enabled five target-features to be identified for further archaeological investigation. Two of these, on top of the mound, were opened in March (Trenches 1 and 2), and Trenches 4 and 3 (Trench 3 will be a bit smaller than what is suggested on the plot below..) will be excavated this August, time and weather permitting.




A plot of the geophysical survey results with suggested trench locations and targets highlighted in red

TRENCH 3: A low resistance arc surrounding the base of the outcrop was noted in the survey. This may mark the location of an artificial ditch, perhaps some 3m in width, or may be natural where water has accumulated. More intriguing is the fact that this possible ditch seems to be placed to the rear side of another geophysical anomaly ('white line') that may be a stone wall surrounding the northern edge of the outcrop. The location of this anomaly is exactly in line with the field boundary to the western side of the monument. This could mean that the feature is the robbed-out stretch of boundary wall to the north of the castle, or – alternatively – that the western boundary lies on the line of a medieval (or earlier?) boundary wall, the northern remains of which have now been shown up through the geophysical survey. Given this, the ditch anomaly may represent either a natural feature or a ditch that predates the construction of the stone boundary wall; establishing whether the wall is of Medieval or Early Modern date might in turn help explain the date and function of the ditch. This would require a large excavation trench to resolve.


TRENCH 4:  Both Davies and Swan (1939, 203) and Jope et al. (1950, ) noted the existence of a what seemed to be the foundation course of a small building located at the south-west corner of the summit enclosure. From its location on the perimeter of the enclosure it can be speculated that this feature is the remains of a wall-tower designed to provide additional defensive strength to this corner of the castle. To establish whether this is indeed the case we will open a small excavation trench across the line of this feature.




Davies, O., and Swan, H.P., 1939: “The Castles of Inishowen”, Ulster Journal of Archaeology 2, 178-208.

Jope, E.M., Jope, H.M., and Johnson, E.A., 1950: “Harry Avery’s Castle, Newtownstewart, County Tyrone: Excavations in 1950”, Ulster Journal of Archaeology 13, 81-92. 

We're Back! LegenDerry DIG No. 2 coming up...

We are heading back to Derry to dig at Elagh Castle, also know as Doherty's Tower next week.


Volunteers are welcome to join in the dig (August 14th- 23rd) - please register with the North West Volunteer Centre


A bit about the castle (from the NI-SMR) -

This was an Irish castle probably dating to the 14th century. It was an O'Doherty stronghold until 1600 when it was abandoned and part demolished by the English. O'Doherty reclaimed it in 1608, but lost it to Chichester who used it for a garrison. It was leased by 1621, and by 1665 had fallen into disrepair. There is evidence remaining of a curtain wall in at least two places west of the existing tower. This tower retains traces of a portcullis slot and is likely to be the surviving portion of a double-towered gateway. There are also traces of a corner tower in the SW of the outcrop on which the castle stood. The various contemporary reports suggest the castle consisted of a lofty square keep with semi-circular towers projecting from two of the angles.