1999:188 - CHRISTCHURCH CATHEDRAL, Dublin, Dublin

As part of redevelopment works to open up the 12th-century crypts to the public, a series of service trenches was excavated in the existing 19th-century concrete floor in the crypt of Christchurch Cathedral. During the monitoring, stone wall remains and some skeletal material were exposed in two of the trenches (Trenches 1 and 2).

After consultation with the relevant authorities it was agreed to open an additional two trenches in the vicinity of the wall features to establish their nature and extent.

Trench 1, orientated east-west, extended the full length of the crypt and was 0.4m wide and 0.25m deep. At the eastern end the depth of rubble/concrete was 0.4m, with boulder clay revealed at the western end. A small area of one-coursed mortared stone revealed in the eastern half of the trench may represent the foundations of a wall; however, this could not be firmly established from the extant remains. It appeared to date to the Anglo-Norman period as two small sherds of medieval pottery were recovered from the trench during trowelling. The mortar used in the wall feature was similar to that in the present building.

At the western end of the trench, in situ skeletal material was exposed, consisting of two femurs orientated east-west.

Trench 2 was orientated north-south to facilitate air-handling ducts. It was 1.4m wide by 0.3m deep. During the initial hand-excavation of this trench, stone remains were exposed, revealing a two-phase stone wall structure lying beneath the present late 12th/13th-century cathedral. The walls appear to represent the north-west corner of a masonry structure, which was reused as a foundation for a pier in the Anglo-Norman period.

The first phase consists of a west wall orientated north-south, 2.6m long and standing two courses high. The top of the north wall of this structure was also exposed, orientated east-west, 4.6m long and 0.4m wide. The full width of the wall could not be ascertained as the base of the crypt pillar was built directly on top. Both walls were bonded by a distinctive, off-white mortar.

The second phase consisted of a second clay-bonded wall built up against the Phase 1 north and west walls. The precise extent and function of this wall could not be established conclusively owing to excavation limitation. It was 0.5m wide and was built of large limestone blocks, one course high, cut into boulder clay. There is a slight curve to the east. At the southern end of Trench 2 some badly decomposed skeletal remains were revealed. They appeared to be the remains of adult lower leg bones orientated east-west.

The earlier remains were comprehensively demolished on the western side and sealed with a hard, redeposited boulder clay. On the eastern side a section of wall was remortared and reused, forming part of the foundation base for the existing crypt pier. The location of the existing pier base obscures the line of the walls, and consequently their nature and extent could not be established fully. However, the stone remains pre-date the present structure, which dates to the 12th/13th century. No finds were recovered associated with the recording of the wall remains; however, two sherds were recovered in a disturbed context at the northern end of the trench, which may suggest that the walls date to the pre-Norman period. All features revealed remain in situ, with a section of the wall features permanently visible.

At the western end of the cathedral the last bay at the southern end had not been concreted over in the 19th century, as all of the remaining crypt floor had been. A beaten slate/mortared floor was revealed in this bay, measuring 2.6m east-west (at its widest) by 5m north-south. A layer of modern sand 0.06m deep covered the surface, which, owing to water seepage, was badly degraded. This floor surface may represent the original crypt floor level or, alternatively, may be a pathway surface associated with a passageway thought to have extended north-south in this area of the crypt.

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