Focus on finds: pumice

Monday, July 20, 2020 (10:00 AM)

Three examples of pumice found at the Ness of Brodgar. (Sigurd Towrie) — Three examples of pumice found at the Ness of Brodgar. (📷 Sigurd Towrie)

While it might not be among the most glamorous of finds from the Ness, there is no doubt that pumice played a role in Neolithic life.

A by-product of volcanic eruption, pumice is hard, rough-textured, vesicular (very small bubbles) and floats.

It can be found on beaches in Scotland’s Western Isles as well as Orkney and Shetland.

Disgorged by volcanic eruptions in Iceland, pumice may have floated at sea for many years before washing ashore.

It is found at archaeological sites across Scotland (and many other places where volcanic action sends it). As the photographs show, it was clearly being used at the Ness of Brodgar complex.

These days pumice is used to scrape dead skin off feet and elbows; to distresses denim; to filter water and put the abrasive in toothpaste, soaps and hand cleansers.

The archaeological pumice had been collected from the shore and taken back to settlements for its abrasive qualities. The grooves and angled faces on the Ness pumice are the most obvious evidence of use – but what was it used for?

Suggestions made by specialists Ann Clarke and Andrea N. Smith include its use on wood, whale and other bone (e.g. bone pins), working skins, burnishing pottery and refining the spatulate tools of the Ness.

Today's large pumice stone from Structure Twelve's eastern annexe. (Sigurd Towrie)

The well-defined groove along the pumice found in the annexe this morning. (Sigurd Towrie)

Experimental work on pumice has not been carried out. We also need to think about uses that don’t leave physical traces on the surface. Perhaps it was crushed and added to animal fat to make an abrasive mixture.

However it was used, it is another example of how people made use of their immediate environment and what it produced.

Its presence at the Ness, and other sites in Orkney across the millennia, allows us further insight into what folk did and how they did it.

And as a footnote, pumice must not be confused with scoria, which also appears in Orkney, which doesn’t float, and probably therefore is a product of the much more ancient volcanic processes of Orkney’s own geological past.