Focus on finds: A natural source for Structure Seventeen’s stone sphere?

During the 2024 excavation season a small, stone sphere emerged from Structure Seventeen. It was given its small find number, 47805, and passed to the finds team.

Stone balls are known in the Orcadian Neolithic, turning up in settlements as well as chambered cairns. These, however, have been deliberately fashioned by human hand and, because they have been ground into shape, are smooth.

Although the Structure Seventeen ball was perfectly round, it wasn’t smooth. In fact, it was consistently rough all over, with a couple of pitted areas. This roughness suggested a natural process, but the shape was a near-perfect sphere, suggesting careful working.

Our geologist, Martha Johnson, has had a look and her thinking on this lovely rock is interesting. 

She identifies it as a water-worn sphere, with medium grey plagioclase feldspar, milky quartz, cream-tan albite with several dark crystals, perhaps garnet, perhaps biotite: not an Orkney rock. 

She suggests it may have been formed into its current shape by action within a pothole in a rocky floored riverbed during the river’s flood stages. There are no such rivers in Orkney. 

What does this all mean?

Martha reckons we have a very hard rock which has been repeatedly turned, by the force of flood water, to make its current shape and surface in a natural bowl like the Punchbowl, in the River Quoich, in Aberdeenshire.  

The stone ball fresh from the trench in 2024.

If that is indeed the case, it was tumbled and tumbled by powerful water-power around a natural rock bowl and eventually spat out before its destruction. And someone found it thousands of years ago!

It ended up in Structure Seventeen at the Ness of Brodgar, having been brought here from a river somewhere south, in Scotland.  

Post-excavation work involves many such pieces of detective work as our specialists work through the vast volume of material. Their knowledge provides explanations and further insights into life at the Ness and so the picture builds, to share with you as we progress.