Far from boring: the Kirkleatham Musseleum

Saint Cuthbert of Lindisfarne is strongly associated with fossils, but the church named after him in Kirkleatham, near Redcar, takes his palaeontology off in a new direction.

The oldest part of St Cuthbert’s Church is its mausoleum, which was erected in 1740 in memory of Marwood William Turner. (The rest of the church was rebuilt in the 19th Century.)

Figure 1. The Turner Mausoleum, St Cuthbert’s Church, Kirkleatham, built of sandstone showing clean-dressed and rusticated faces.

The mausoleum was designed by James Gibbs, and features a remarkable quantity of vermicular rustication (Fig. 1). As a fan of all things vermicular, I was predisposed to like it, but then the tapestry and ceramic artist (and Lemon Tops & Lobster Pots curator, and member of my family) Jane Riley showed me some features she had spotted in the plinth (Fig. 2). There, the stone also had a rusticated fabric, but this time it was natural.

Figure 2. The plinth of the Turner Mausoleum, Kirkleatham, showing its natural stone textures.

The sandstone used for the plinth (and a few other adjacent structures, including the churchyard wall) is packed full of fossilized shells (Fig. 3), especially mussel-like bivalves (Fig. 4). I’ve not carried out a proper palaeontological study, but they look Early Jurassic to me.

Figure 3. Close-up of the sandstone used in the plinth of the Turner Mausoleum, showing that it is packed full of fossilized mollusc shells.
Figure 4. A fragment of mussel-like (mytilid) fossil bivalve (possibly Modiolus) from the sandstone plinth of the Turner Mausoleum, Kirkleatham.

Jane hadn’t just noticed the fossils, though. She’d also spotted that the plinth stones were full of holes, as you can see in Figure 3. These were giving the rock its rusticated appearance, and Jane knew what they were: borings made by pholadid bivalves, more commonly known as piddocks. Even better, some of the borings still contained their borer!

Figure 5. Piddocks (pholadid bivalves) in situ in the bored sandstone plinth of the Turner Mausoleum, Kirkleatham, Redcar.

Elsewhere among the plinth stones you can find barnacles, serpulid worms, and limpets. Piddocks, limpets, serpulids and barnacles all live in the sea, so what are they doing in an 18th Century mausoleum on the outskirts of Redcar?

My best guess is that the plinth sandstones were quarried from the Cleveland coast, where they had been forming intertidal scars. At Coatham Rocks, on the west end of Redcar beach, the Early Jurassic Staithes Sandstone Formation crops out at low tide (Fig. 6). These rocks contain plenty of fossils, including lots of bivalves; indeed, the boundary between the Staithes Sandstone Formation and the underlying Redcar Mudstone Formation is marked by an ‘Oyster Bed’.

Figure 6. Excerpt of the British Geological Survey map of Redcar, showing the Staithes Sandstone Formation (darker red) and Redcar Mudstone Formation (paler red) of Coatham Rocks. (Reproduced with the permission of the British Geological Survey (C) UKRI 2023. All rights reserved.)

So, subject to further research, my hypothesis for the Musseleum timeline is as follows:
1. Sandy, shelly sediments deposited on Jurassic sea floor of Cleveland, around 186 million years ago.
2. Sediments buried and lithified, eventually returning to surface due to tectonic forces.
3. Shelly sandstones form rocky coastal scars, ideal habitat for piddocks and their friends.
4. Bored coastal sandstones are quarried and taken to Kirkleatham, no more recently than 1740.
5. Removed, confused, and then deceased, piddocks remain in mausoleum plinth-stones for at least 283 years.

Thanks so much to Jane for alerting me to this amazing building!

Earth scientist in York, fossilist across Yorkshire. Co-director of the Yorkshire Fossil Festival and palaeontologist for hire. Can be found twittering, facebooking, and instagramming as @fossiliam.