Oyster shell inserts at Glastonbury Tor
Back in 2010, I presented a poster on shells in archaeological building materials at the International Council for Archaeozoology conference in Paris, which was published as a book chapter last year (you can read and download a proof copy here). One thing I mentioned was the use of oyster shell, especially the flat right valves of the oyster as a structural insert in between blocks of masonry. Yesterday morning I came across a striking example of this in the north eastern door of the ruined St Michael’s Tower on Glastonbury Tor, where there is a short series of oyster shells in a buff mortar matrix between two courses of masonry. These are very likely to be quite a late insertion, probably nineteenth century when some rebuilding work was done on the tower.