The non-completion theory of Stonehenge is fully explored in the EH Research Report Series 32-20 12
I have tried to condense the relevant bits below but please download the full report from the link above.
In brief there is no evidence for stones 17, 18 and 24 of the Sarsen Circle.
The parch marks I photographed 19/7/13 - see http://www.sarsen.org/2013/07/partch-marks-at-stonehenge.html - show marks consistent with holes for 17, 18, 19 and 20, so they suggest that these stones were actually erected.
Extracts from STONEHENGE LASER SCAN: ARCHAEOLOGICAL ANALYSIS REPORT:
Breaking Stonehenge: evidence for stone-breaking and the removal of stones
Although a large number of stones survive at Stonehenge, the monument is nowhere
near complete. This has led many authors, including john Wood (1747), William
Hinders Petrie (1880), Paul Ashbee (1998) and Christopher Tilley eta!. (2007) to
question whether the monument was ever finished. The non-completion theory is in
part based on the use of what have been perceived as small and inadequate stones
in the monument (e.g Stones Il and 22), but it also relies on limited evidence for the
removal of stones and slighting of the monument (Ashbee 1998). It is certainly true
that there is no documentary evidence for the removal of stones or deliberate slighting
unlike Avebury, but it is questionable whether we would expect such documents for
a site located well away from medieval settlement. The current project has, however
revealed physical evidence for stone-breaking and the removal of stones. This evidence is
presented below in relation to the main structural elements, and its implications for the
non-completion theory are explored in the discussion.....
The Sarsen Circle envisaged by Petrie (1880) was composed of 30 uprights and 30
lintels. Sixteen uprights survive complete, the majority of which are located on the NE
half of the monument, and one upright is broken (Stone Il). Two uprights lie complete
on the ground (Stones 12 and 14) and a further six uprights are represented by broken
fragments (8, 9, 15, 19, 25 and 26). Five uprights are not present at Stonehenge, although
they were speculatively numbered by Petrie (Stones 13, 17, 18, 20 and 24). Of the 30
lintels, six survive in place (Lintels IGL 102, 105, 107, 122 and 130) and two are represented
by fragments on the ground (Lintels 120 and 127); 22 are not present on the site.....
It is therefore pertinent to ask if there is any evidence that the missing uprights (Stones
13, 17, 18, 20 and 24) were ever present at Stonehenge? In summary, there ¡s certainly
good circumstantial evidence that all of these stones may have been present. The
presence of fallen Lintel 120 can be taken to suggest that Stone 20 was once present
and erect, Hawley excavated a stone hole for the missing Stone 13 and, within its backfill,
there was evidence that a stone had been broken up.....
The surviving tenons on the uprights may provide another means of considering whether
lintels and missing uprights were once present. In order to achieve an accurate alignment,
one of these elements has to be manufactured first, so the location of the other element
can be accurately determined......
If this is correct then the presence of a tenon would indicate that a lintel once existed on
the upright1 Notably, tenons are present on the tops of Stones 16, 19 and 23, which are
adjacent to the three missing uprights and, by implication following Atkinson’s argument,
these stones must have been present to support the lintels. This argument also has
significant implications for the missing lintels as the only locations where tenons are not
present are the damaged/missing tops of Stones 5 (S side only), 8, 9 (NE side only, 11, 15
(NW side only), 21(SE side only), 25 and 26. The surviving tenons may therefore indicate
that 18 of the 22 missing lintels were once present.....
Incomplete or imperfect and damaged: the non-completion theory re-considered
Ever since John Wood (1747) wondered why so many of the lintels were missing from
Stonehenge, and how any would-be stone robber might have removed them without
damaging the uprights, successive authors have questioned whether Stonehenge was eve
finished. After accurately surveying the monument, William Flinders Petrie invigorated
the debate, stating:
"The evidence for non-completion of the outer sarsens, is in the very
much smaller Stone 11.,,. Again Nos. 21 and 23 are both defective in
size compared with the rest; these show that 11 was no single freak,
but was the result of not having better material. If the builders ran so
short as to have to use such a stone as 11, is it not very probably that
they had not enough to finish the circle?’ (Petrie 1880, 16)
This issue is still hotly debated; Christopher Tilley eta!. (2007) argue that the monument
was not completed, while Anthony Johnson (2008, 146) argues for a finished monument
This debate was also considered by David Field and Trevor Pearson following their surve
of Stonehenge (2010, 62-66). Analysis of the laser-scan data has revealed significant new
evidence that informs, rather than solves, this debate. Key aspects of the non-completion
theory are reviewed. These are:
• The presence and use of ‘inadequate’ stones (e.g Stones Il and 21).
• The absence of approximately one third of the Sarsen Circle on the SW side of the
monument and the absence of the majority of the lintels.
• The absence of documentary evidence for the removal of stones or slighting of the
The use of inadequate stones, particularly on the SW half of the monument, is central
to the non-completion theory. ......
In conclusion, this study provides evidence that 27 of 30 uprights of the Sarsen Circle
were certainly erected, and the presence of tenons on adjacent uprihts may indicate
that all were present along with at least 26 of the 30 lintels. There is certainly no
convincing evidence that the circle remained incomplete, and in the light of the significant
degree of demonstrable stone robbing it is possible that a complete Sarsen Circle once
existed. It is, however clear that the Sarsen Circle was never a perfectly symmetrical
circle of regular pillar and lintels. Its SW half was not as well constructed as the surviving
NE halt the stones were smaller less regularly shaped and their exterior surfaces were
left coarsely dressed or entirely unworked.