Replica of St John's Cross, Iona Abbey, Isle of Iona

St John's Cross Replica, Iona Abbey

This reinforced concrete replica of St John's Cross was erected in 1970 and stands as a Grade A heritage structure. It is an accurate copy of an iconic early medieval freestanding cross dating to around AD800, which originally stood on the Isle of Iona.

The Original Cross and Its History

The original cross was a ringed cross decorated with intricate ornament of largely non-figural nature, including prominent bosses, snake-and-boss ornaments, interlace, diagonal fret, key pattern, spirals, and zoomorphic designs. The decoration also features possible Virgin-and-Child motifs and what is interpreted as Jacob wrestling with the angel. The original cross is believed to have originally been ringless, with ring quadrants introduced early, probably after an initial collapse, to support the cross arms.

Given its location and structural weaknesses in its tenon joints, the original cross collapsed at least four times during its life. Attempted reconstructions were made in situ in 1927 and 1954, but the cross fell for the final time in 1957. These cycles of collapse and repair damaged the original components so severely that it could no longer be re-erected outside.

Commission and Design of the Replica

The Iona Cathedral Trustees and the Ancient Monument Board for Scotland decided on a permanent solution and commissioned what they termed an authentic replica. The design brief specified that the replica should accurately resemble the original in colour, texture and detail while being durable enough to withstand the extreme weather of the Hebridean island. This requirement ruled out using the original stone material.

From 1968, George Mancini, an artistic bronze founder, worked with Norman Robertson, a researcher at the Ministry of Works, to create a plaster model of the cross based on plaster casts of the original pieces. The model omitted the prominent boss on the east face of the original, which had only recently been discovered.

Construction and Technical Details

In 1970, Exposagg Limited cast, transported and erected the replica. John R. Scott, the consulting engineer, designed the concrete replica to resist strong winds and the corrosive maritime environment using reinforcement of 5mm nickel steel bars. John Lawrie from Edinburgh College of Art undertook the casting of Mancini's model using large gelatine moulds to recreate the finish and texture of the original.

Colour samples were taken from the original quarry location and matched with a natural green Dolorite aggregate used for both coarse and fine aggregates. Black iron oxide pigment was added to create an ageing effect.

The cross was made in five parts and assembled into three sections (head, shaft and base) for transportation. It was post-tensioned vertically by high-tensile wires, and the junction between head and shaft was pre-stressed to avoid failure in the joint, which had been a recurring problem in the original. The two faces of the cross were joined by bars with epoxy resin mortar at the edges.

Location and Setting

The replica stands in a concrete foundation around which the surviving stones from the base of the original mid-8th century cross have been reinstated. It stands immediately in front of the west gable of the small reconstructed shrine-chapel known as St Columba's Shrine.

In 1970, excavations conducted by Stewart Cruden, Inspector of Ancient Monuments, revealed that the unusual composite base was contemporary with the high cross. The excavation uncovered two massive integral socket stones, which were removed to the grounds of the Nunnery when the replica was erected so it could sit in its concrete foundations.

In 1990, the surviving parts of the original cross were re-erected in the museum within the reconstructed infirmary of Iona Abbey, where they form the focal point of an exhibition.