Y and Z Holes

The Y and Z Holes are two rings of concentric (though irregular) circuits of 30 and 29 near identical pits cut around the outside of the Sarsen Circle at Stonehenge. The current view is that both circuits are contemporary. Radiocarbon dating of antlers deliberately placed in hole Y 30 provided a date of around 1600 BC, a slightly earlier date was determined for material retrieved from Z 29. These dates make the Y and Z holes the last known structural activity at Stonehenge.

The holes were discovered in 1923 by William Hawley, who, on removing the topsoil over a wide area noted them as clearly visible patches of ‘humus’ against the chalk substrate. Hawley named them the ‘Y’ and ‘Z’ because for a short time he had earlier labeled the recently discovered Aubrey Holes the ‘X’ holes. 18 of the Y Holes have been excavated and 16 of the Z Holes. Further evidence of the Y and Z Holes being late in the sequence of events at Stonehenge is demonstrated by the fact that hole Z 7 was found to cut into the backfill of the construction ramp for stone 7 of the Sarsen Circle.

The outer Y ring consists of 30 holes averaging 1.7 m × 1.14 m tapering to a flat base typically close to 1 m × 0.5 m, the inner Z holes, of which only 29 holes are known (the missing hole Z 8 may lie beneath the fallen Sarsen stone 8), are slightly larger, on average by some 0.1 m. They can be best described morphologically as ‘wedge-shaped’. The diameter of the Y Hole circuit, i.e. the best-fit circle is some 54 m, that of the Z Hole series, around 39 m.

The fills of the holes was found to be largely stone-free, these deposits are thought to be the result of the gradual accumulation of wind-blown material. Examples of almost every material, both natural and artefactual, that have been found elsewhere at Stonehenge have been retrieved from their fills; this includes pottery of later periods (Iron Age, Romano-British, and Medieval) also coins, horseshoe nails, and even human remains.

A new landscape investigation of the Stonehenge site was conducted in April 2009 and a shallow bank, little more than 10 cm (4 inches) high, was identified between the two hole-circles. A further bank lies inside the Z Hole circle. These are interpreted as the spread of spoil from the original holes, or more speculatively as hedge banks from vegetation deliberately planted to screen the activities within.

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Wikipedia