Focus on finds: Skaill knives (and how to make them)

Thursday, November 13, 2025 (10:20 AM)

“There is one type of stone implement very abundant at Skaill. These are flakes of hard old red sandstone. […] One edge is always thicker than the other, which is almost invariably very sharp.”

George Petrie. Notice of ruins of ancient dwellings at Skara, Bay of Skaill,
in the parish of Sandwick, Orkney, recently excavated (1867)

Skaill knives. (Ann Clarke/annrocks.co.uk) — Skaill knives. (📷 Ann Clarke/annrocks.co.uk)

Not all the stone tools from the Ness of Brodgar are works of exquisite craftsmanship that took patience and skill to fashion. Some are obviously purely functional – none more so than “Skaill knives”.

These are simple, handheld stone “blades” created by striking a flake from a large, rounded, sandstone cobble.

Skaill knives exhibiting edge damage. (Clarke 2006)

During excavations at Skara Brae in the late 1920s, Gordon Childe found these flakes in such quantities that he named them Skaill knives.

Why?

Because Skara Brae sits on the southern shore of the Bay of Skaill.

The process to create a Skaill knife is very simple.

Throw a suitable beach cobble against another secure stone (but stand back – they can bounce!). The resulting flake has a sharp edge, providing a cutting tool that experimental work has shown to be highly efficient at butchery [1].

It was the Orcadian antiquarian George Petrie who recognised Skaill knives for what they were. In 1867, almost 20 years after Skara Brae was exposed by the elements, Petrie wrote: “There is one type of stone implement very abundant at Skaill.” [2]

These flakes had been:

“…broken off from water-worn stones, and have invariably one side smooth, while the other shows the fracture. One edge is always thicker than the other, which is almost invariably very sharp.” [2]

Petrie added:

“There were hundreds of those flakes found at Skara, but not one has received the slightest polish, and very few of those found seem to have been used, as most of their edges are as sharp as if the flakes had been newly detached.” [2]

Skaill knives from Pool, Sanday, with their edges reworked. (Clarke 2006)

Although certain the flakes were not the result of natural attrition, Petrie was perplexed. “The process by which these rude stone implements had been obtained seemed to be still a matter of doubt,” he declared.

To him the answer came on a visit to Westray, where Petrie witnessed his son hurling beach stones on the rocks. The boy, he realised, had “unwittingly rediscovered the ancient mode of producing the rude stone implements”.

Petrie had been investigating a “kitchen midden” within some “artificial mounds”. Excavating with a pocket-knife, he and a colleague found “great numbers of stone flakes similar to those from Skara”. [2]

The artefacts were clearly on his mind when he later encountered a stone on the beach. It had clearly been broken a few hours earlier, but by natural causes.

“On lifting it, I saw, with some surprise, that a flake of a circular shape had been recently struck from it, and at the upper edge, where the stroke had taken effect, was a notch, the counterpart of those by which the flakes found at Skara are characterised.”

Watching the results of his son’s stone-breaking exploits, Petrie had a go himself:

“I dashed the broken stone, which I still held in my hand, on the rocks and as I confidently expected, and to my great delight, a flake was detached as good as any found at Skara.

“I frequently repeated the experiment, and with invariable success; and I have little doubt that such was the simple mode by which the flakes of the ancient kitchen middens in Orkney were generally obtained.

“To break them off with another stone wielded in the hand, would be a process both tedious and uncertain in its results. I believe a much more powerful stroke than can be given in that way is necessary to produce a notch like the one which is always made by dashing the stone on the rocks, or on another stone of sufficient size and hardness to resist the blow.” [2]

While Petrie was correct in some respects, my own personal experiments (far from scientific) have confirmed that hurling beach cobbles at rocks is not a very practical way to create Skaill knives. The success rate was very low, perhaps about one in thirty – not a very efficient, nor reliable, way to produce large quantities of the stone tool.

Petrie’s theory is further questioned in a study of the Skaill knives from the Ness of Brodgar, due to be published shortly in The Journal of Lithic Studies.

This noted consistent impact points in the centre of the thinnest side of the cobble where it had been struck:

“As such, it seems unlikely that these knives were produced by randomly dashing cobbles against rocks.” [3]

Instead, based on the evidence the authors propose that the Ness Skaill knives were created by deliberately, and carefully, striking specific points of the parent stone to split it. [3]

The nature of their fabrication means that Skaill knives can vary in size, with their shape dictated by that of the parent cobble.

“The typical Skaill knife is … often squat to round in shape with a thick proximal end that enables it to be gripped comfortably in the palm of the hand, leaving free a long, unmodified working edge. No physical evidence remains to indicate that these flakes were ever hafted prior to their use.” [1]

A decorated Skaill knife from Skara Brae, recorded by Anne Clarke in 1989 while recording the stool tool assemblage recovered during the 1970s excavations. — A decorated Skaill knife from Skara Brae, recorded by Anne Clarke in 1989 while recording the stone tool assemblage recovered during the 1970s excavations. (Saville 1994)

Few excavated examples show evidence of reworking – it seems they were used until the sharp edge dulled, or was damaged, and then thrown away.

“The Skaill knife can therefore be regarded as a tool that is quickly and easily produced from an almost infinite stone resource. There is very little evidence for the curation of these flakes, and they can be viewed as highly disposable items, sometimes found in great numbers, which may well have been used only once before being discarded.” [1]

The Bay of Skaill, Sandwick, Orkney. Looking south towards Skara Brae, with an 'almost infinite' supply of raw material for Skaill knives in the foreground. (Sigurd Towrie) — The Bay of Skaill, Sandwick, Orkney. Looking south towards Skara Brae, with an ‘almost infinite’ supply of raw material for Skaill knives in the foreground. (📷 Sigurd Towrie)

As mentioned previously, it seems likely that Skaill knives primary role related to butchery. Evidence gathered by lithics specialist Ann Clarke has shown that, for this purpose, they were extremely efficient:

“The modern-day butcher uses a selection of knives and choppers of varying shapes and sizes; this was reflected in the choice of flakes in [an] experimental butchering session where the butcher selected the smallest flakes for skinning and the largest for chopping bone, with intermediate sizes used for a wide range of tasks.,

“The shape and size ranges of the [Skaill knives] found in the prehistoric assemblages would easily accommodate this need for selectivity in tool shapes and sizes.” [1]

Notes

[1] Clarke, A. (2006) Stone tools and the Prehistory of the Northern Isles (Vol. 406). British Archaeological Reports Limited.
[2] Petrie, G. (1867) Notice of ruins of ancient dwellings at Skara, Bay of Skaill, in the Parish of Sandwick, Orkney, recently excavated. In Proceedings of the Society of Antiquaries of Scotland (Vol. 7, pp. 201-219).
[3] Van den Dikkenberg, L., Lyons, J., Foley, T., Fitton, L., Card, N., Edmonds, M. and Little, A. (forthcoming) Skaill knives from the Ness of Brodgar: an experimental pilot study exploring their potential for functional- and technological analysis. Journal of Lithic Studies.