The approach to the chapter house is through a rib-vaulted ante-room 3 bays wide, whose pointed arches provide a solution to that room's rectangular shape. Carved pointed arches also appear in the decoration of the chapter house itself. Here they arise from the intersections of the interlaced semicircular arcading, which runs continuously around the walls. The chapter house has a quadripartite ribbed vault high. The ribs, walls and columns display a complex interplay of carved patterns: chevron, spiral, nailhead, lozenge and zigzag.