St. Peter and St. Paul’s Church, Gosberton
A crossing is the name architects give to the junction of the four arms of a cross-shaped church.
St. Peter and St. Paul’s Church in Gosberton has this shape. It’s crossing is surmounted by the tower.
The Groined Vault
The ground floor level of the church tower consists of four piers (pillars), each with open arches. The arched structures on each of the four sides extend inwards to form what is known as a groined vault.
What is a groined vault?
Many early vaults were single-barrelled.. A single barrel vault, also known as a tunnel vault, wagon vault or wagonhead vault, is an architectural element formed by the extrusion of a single curve along a given distance. The curves are typically circular in shape, lending a semi-cylindrical appearance to the total design.
As with all arch-based constructions, there is an outward thrust generated against the walls underneath a barrel vault. To absorb the thrust the walls need to be exceedingly thick and strong, perhaps reinforced by buttressing.
However, in the case of vaulting such as we have here in the crossing of St. Peter and St. Paul’s church, which holds above it the (extremely heavy) tower, there are no walls, only piers, as the ground floor space needs to be open, for obvious reasons.
To ensure the weight of the tower can still safely be supported, the piers supporting it are very thick – much bulkier than the piers elsewhere in the church. This alone would not have been enough to support the tower. Rather than just having a single barrel vault, the tower is supported by a double barrel or groined vault – two intersecting barrels crossing over each other at right angles. The joints where they intersect, called groins, create a pleasing cross-shaped design. More importantly, they ensure that the force of weight (the thrust) of the tower it supports is channeled to the four supporting piers at each corner.
Whilst the groined vault is a marvellous piece of structural engineering, it can be appreciated simply as a stunning piece of medieval aesthetics and craftsmanship.
