Aubrey holes
Encyclopedia
The Aubrey holes are a ring of fifty-six (56) Late Cretaceous
(Santonian
Age) Seaford Chalk
pits at Stonehenge
named after the seventeenth-century antiquarian
John Aubrey
. They date to the earliest phases of Stonehenge in the late fourth and early third millennium BC. Despite decades of argument and analysis, their purpose is still unknown although an astronomical
role has often been suggested.
Whilst visiting the monument in 1666, Aubrey noticed five circular cavities in the ground and noted them in his records. These features were ignored or not seen by the later antiquarians to investigate the site, and it was not until the 1920s during the work carried out by Colonel William Hawley
that Hawley's assistant Robert Newall identified a ring of pits he named in honour of Aubrey and his early survey.
The depressions seen by Aubrey himself are more likely to have been different features to those that now bear his name. Mike Pitts
in a 1981 article in Nature
pointed out that the holes had been backfilled thousands of years before Aubrey visited the site. The presence of later cremation burials and sarsen
stone chips in the holes' upper fills supports this. That none of the other antiquarians who visited the site noticed any such holes implies that they were not permanent features either. Pitts argues that they were more likely to be the cavities left by features that had recently been removed. He has suggested that perhaps further megaliths stood at Stonehenge which occupied these other holes and are now lost.
dug two more Aubrey Holes which brought the total excavated to thirty-five, including one that Richard Colt Hoare
may have encountered whilst digging beneath the fallen Slaughter Stone in the early nineteenth century. It was found that the pits were an average of 0.76m deep and 1.06m in diameter. Twenty-five of the pits contained later cremation
burials inserted into their upper fills along with long bone pins which may have secured leather or cloth bags used to hold the remains. Their presence makes Stonehenge Britain's oldest cremation cemetery.
The pits appear to have been refilled with the freshly excavated chalk
rubble soon after being dug as no weathering has been noted on the chalk sides of the pits. They may also have been dug out and refilled numerous times. The holes are in an accurate, 271.6m circumference circle, distributed around the edge of the area enclosed by Stonehenge's earth bank, with an average standard deviation
in their positioning of 0.4m. The circle they describe is around 5m inside the monument's bank. Twenty-one of the holes remain unexcavated and no reliable dating material has been recovered from the other thirty-five. The only available carbon date from the holes comes from charcoal in one of the later cremations. It gives the broad range of 2919-1519 cal BC. That sarsen
stone chips have only been found in the upper fills of the excavated pits implies that the digging of the holes predates the megalithic phases of Stonehenge. From this stratigraphic evidence it is therefore likely that the holes were dug during the first phase of the monument, Stonehenge 1 (around 3100 BC) and were then reused for burials during Stonehenge 2 in successive centuries. By the time the standing stones of Stonehenge 3 were erected (around 2600 BC), the holes had fallen out of use.
The positions of the holes are today marked at the Stonehenge site by white discs laid in the ground surface. Archaeologists number them 1 to 56 counting clockwise from the later Slaughter Stone at the eastern side of the north east entrance. Hawley reburied the human cremations he found, placing them in the backfilled hole number 7. These remains were re-excavated in August 2008 as part of the Stonehenge Riverside Project
.
, which marked the point of the midsummer sunrise, viewed from the centre of the henge. The Heel Stone is now attributed to Stonehenge 3 and was therefore not contemporary with the holes.
It has been suggested that the Aubrey holes were originally intended to be posthole
s containing timbers or stones but this is uncertain. Analogous timber circle
s at sites such as Woodhenge
have influenced this interpretation; the positioning of the Aubrey Hole circle relative to the earth bank and ditch at Stonehenge is reproduced at similar sites with rings of timber postholes. That the holes appear to have been filled soon after excavation and then possibly redug does not exclude the possibility that they held timber posts which were replaced intermittently. No evidence of postpipe
s has been recovered with the holes although modern archaeological excavation techniques have not been applied to the pits. If the putative timbers were purposefully removed when they fell out of use, then even this evidence would be difficult to spot however. The lack of full documentation from the early Stonehenge digs in the twentieth century and the disturbance caused by the insertion of the later cremations during Stonehenge 2 have also added to the uncertainty over the function of the holes.
In a survey of twentieth-century excavations at Stonehenge, English Heritage
's Stonehenge in its landscape
, archaeologist Karen Walker collated and studied the surviving records from all the earlier work on the holes and concluded that "Although the evidence is inconclusive, and will no doubt be the subject of continued debate, the authors are inclined to support the view that the Aubrey Holes held posts, which were removed, rather than burnt in situ or left to decay."
In August 2008, further excavation of Aubrey Hole 7 by Mike Parker-Pearson, Mike Pitts
and Julian Richards
led the archaeologists to suggest that the 56 holes held Welsh bluestones. Professor Parker-Pearson said: "It's very exciting that we have evidence for stones right from its beginnings around 3000 BC. That's almost 500 years earlier than anyone had thought."
An early attempt to analyse the positions of the Aubrey holes was undertaken by Gerald Hawkins
a professor of astronomy at Boston University
in the 1960s using an IBM 7090
computer. In his book Stonehenge Decoded, Hawkins argued that the various features at the Stonehenge monument were arranged in such a way to predict a variety of astronomical events. He believed that the key to the holes' purpose was the lunar eclipse
, which occurs on average about once a year on a 346.62 day cycle. Lunar eclipses are not always visible as the moon may be below the horizon as it moves across the sky, but over 18 to 19 years (18.61 years to be precise) the date and position of a visible eclipse will return to its beginning point on the horizon again. As the motion of the moon's orbit also causes it to work its way across the sky on an 18.61 year cycle in what is known as the journey between major and minor standstill and back, the theory that this period was both measurable and useful to Neolithic peoples seemed attractive. Lunar movements may have had calendrical significance to early peoples, especially farmers who would have benefited from the division of the year into periods which indicated the best times for planting. 18.61 is not a whole number and so it cannot be used to predict an eclipse without precision equipment and using only crude stones or timber posts in a circle instead. Hawkins' theory was that three 18.61 year cycles multiply out to 55.83 however, which is much closer to an integer
and therefore easier to mark using 56 holes. Hawkins argued that the Aubrey Holes were used to keep track of this long time period and could accurately predict the recurrence of a lunar eclipse on the same azimuth, that which aligned with the Heel Stone, every 56 years. Going further, by placing marker stones at the ninth, eighteenth, twenty-eighth, thirty-seventh, forty-sixth and fifty sixth holes, Hawkins deduced that other intermediate lunar eclipses could also be predicted.
More recent examination, notably by Richard Atkinson, has proved Hawkins largely wrong as it is now established that the different features at the monument that he tried to incorporate into many of his alignment theories were in use at different times and could not have worked alone. The lateness of the installation of the Heel Stone being the final nail in the coffin. Furthermore, the 56 year period is not in fact a reliable method of predicting eclipses and it is now accepted that they never repeat their date and position over three consecutive 18.61 year-long lunar cycles. Hawkins' theories also required strict observance of the phases of the moon which further complicated predictions using his model.
In 1966 Sir Fred Hoyle
examined the arguments in favour of an astronomical purpose for the holes and concluded that the 28 day lunar cycle could still have been indicated by moving a marker stone representing the moon anticlockwise by two holes every day, ending up with 56 holes in total. By moving another marker anticlockwise two holes every thirteen days and which represented the Sun, an annual journey around the circle could also be made. Two further marker stones would also have had to be moved round three holes per year to represent the points where the moon (or rather its marker) crossed the Sun marker's path. Hoyle proved that this could have been used to produce a much more reliable method of predicting eclipse
s as whenever the moon and sun markers are directly opposite each other and the other two stones occupy those same opposing points, an eclipse can be guaranteed. This also has the additional benefit of not needing any standing stones to be present at the site.
Although less complex and romantic than Hawkins' 'stone age calculator' such a technique is certainly feasible if only in theory. Much more elaborate predictive practices have also been suggested for the holes although all these methods, including Hoyle's, require a high level of astronomical awareness and a grasp of some very abstract concepts including knowing where and when to first position the stones around the circle. It has also been pointed out by R. Colton and R. L. Martin that simpler methods exist, based on observing the position of each moonrise, which would have worked just as well and which would not require moving numerous markers amongst 56 holes. This diminishes the astronomical significance of the number of the Aubrey Holes and their circular arrangement and tends to suggest that any astronomical purpose for the site may have been no more than symbolic.
On astronomical symbolism several analysts from Gerald Hawkins to Anthony Johnson (ref. 3 ; pages 259-260) have noted that Plutarch ( in the Moralia, V) reported that Typhon / Seth in Egyptian and Greek myth was identified as the shadow of the Earth which covers the Moon during lunar eclipses. Plutarch further records that the Pythagoreans symbolically associated Typhon with a polygon of 56 sides. The connection of 56 to lunar eclipses is explicit.
and other Neolithic timber circles. Such a view contradicts the archaeo-astronomical view of the holes as being a unique predictive device.
In fact, early Stonehenge may have been barely different from the other Neolithic timber circle
s of the British Isles which had varying numbers of postholes and orientations and could therefore not have been used for in island-wide eclipse predicting. The interpretation of such timber circles is unclear, although parallels were drawn with Native American totem pole
s by Stuart Piggott
in a 1946 BBC
radio lecture. A 50 cm high carved wooden figure found in the Thames Marshes in 1912 and carbon dated to 2460-1980 BC has been used rather tenuously to support the theory of carved wooden posts serving a more terrestrial purpose.
Another possible explanation for the holes, suggested by Richard Atkinson, is that they were excavated in turn in some unknown ritual
involving a procession around the inside of the monument. Others have pointed out the significance of the 28 day human menstrual cycle
and argued that the holes may have been fertility indicators. Alexander Thom
calculated that the circle of holes had been laid out in a circumference of 131 of his megalithic rods although this number has no known significance. A recent CAD study of the holes has shown that a fifty-six sided polygon can be generated by the simple use of square and circle geometry. Aubrey Burl also notes that the azimuth of the Heel Stone, beyond the Aubrey Circle, marks the mid-point in the swing of the Moon between major and minor standstill points, at 51.3 degrees.
The true purpose of the holes may never be known, although future excavation of the remaining twenty-four using modern archaeological techniques will certainly provide more information.
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
(Santonian
Santonian
The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous epoch or Upper Cretaceous series. It spans the time between 85.8 ± 0.7 mya and 83.5 ± 0.7 mya...
Age) Seaford Chalk
Chalk
Chalk is a soft, white, porous sedimentary rock, a form of limestone composed of the mineral calcite. Calcite is calcium carbonate or CaCO3. It forms under reasonably deep marine conditions from the gradual accumulation of minute calcite plates shed from micro-organisms called coccolithophores....
pits at Stonehenge
Stonehenge
Stonehenge is a prehistoric monument located in the English county of Wiltshire, about west of Amesbury and north of Salisbury. One of the most famous sites in the world, Stonehenge is composed of a circular setting of large standing stones set within earthworks...
named after the seventeenth-century antiquarian
Antiquarian
An antiquarian or antiquary is an aficionado or student of antiquities or things of the past. More specifically, the term is used for those who study history with particular attention to ancient objects of art or science, archaeological and historic sites, or historic archives and manuscripts...
John Aubrey
John Aubrey
John Aubrey FRS, was an English antiquary, natural philosopher and writer. He is perhaps best known as the author of the collection of short biographical pieces usually referred to as Brief Lives...
. They date to the earliest phases of Stonehenge in the late fourth and early third millennium BC. Despite decades of argument and analysis, their purpose is still unknown although an astronomical
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...
role has often been suggested.
Whilst visiting the monument in 1666, Aubrey noticed five circular cavities in the ground and noted them in his records. These features were ignored or not seen by the later antiquarians to investigate the site, and it was not until the 1920s during the work carried out by Colonel William Hawley
William Hawley
Lieutenant-Colonel William Hawley was a British archaeologist who most famously undertook pioneering excavations at Stonehenge....
that Hawley's assistant Robert Newall identified a ring of pits he named in honour of Aubrey and his early survey.
The depressions seen by Aubrey himself are more likely to have been different features to those that now bear his name. Mike Pitts
Mike Pitts
Michael Anthony Pitts is a former professional American football defensive end in the National Football League for the Atlanta Falcons, Philadelphia Eagles, and the New England Patriots. He played college football at the University of Alabama and was drafted in the first round of the 1983 NFL...
in a 1981 article in Nature
Nature (journal)
Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...
pointed out that the holes had been backfilled thousands of years before Aubrey visited the site. The presence of later cremation burials and sarsen
Sarsen
Sarsen stones are sandstone blocks found in quantity in the United Kingdom on Salisbury Plain, the Marlborough Downs, in Kent, and in smaller quantities in Berkshire, Essex, Oxfordshire, Dorset and Hampshire...
stone chips in the holes' upper fills supports this. That none of the other antiquarians who visited the site noticed any such holes implies that they were not permanent features either. Pitts argues that they were more likely to be the cavities left by features that had recently been removed. He has suggested that perhaps further megaliths stood at Stonehenge which occupied these other holes and are now lost.
The Aubrey holes themselves
Twenty-five of the holes were excavated by Hawley in 1920 and seven more in 1924. In 1950 Stuart Piggott and Richard AtkinsonRichard Atkinson
Richard Atkinson may refer to:*Richard C. Atkinson , American psychologist and former president of the University of California*Richard J. C. Atkinson , British prehistorian and archaeologist*Richard Merrill Atkinson , U.S...
dug two more Aubrey Holes which brought the total excavated to thirty-five, including one that Richard Colt Hoare
Richard Colt Hoare
Sir Richard Colt Hoare, 2nd Baronet FRS was an English antiquarian, archaeologist, artist, and traveller of the 18th and 19th centuries, the first major figure in the detailed study of the history of his home county, Wiltshire.-Career:Hoare was descended from Sir Richard Hoare, Lord Mayor of...
may have encountered whilst digging beneath the fallen Slaughter Stone in the early nineteenth century. It was found that the pits were an average of 0.76m deep and 1.06m in diameter. Twenty-five of the pits contained later cremation
Cremation
Cremation is the process of reducing bodies to basic chemical compounds such as gasses and bone fragments. This is accomplished through high-temperature burning, vaporization and oxidation....
burials inserted into their upper fills along with long bone pins which may have secured leather or cloth bags used to hold the remains. Their presence makes Stonehenge Britain's oldest cremation cemetery.
Chalk
Chalk is a soft, white, porous sedimentary rock, a form of limestone composed of the mineral calcite. Calcite is calcium carbonate or CaCO3. It forms under reasonably deep marine conditions from the gradual accumulation of minute calcite plates shed from micro-organisms called coccolithophores....
rubble soon after being dug as no weathering has been noted on the chalk sides of the pits. They may also have been dug out and refilled numerous times. The holes are in an accurate, 271.6m circumference circle, distributed around the edge of the area enclosed by Stonehenge's earth bank, with an average standard deviation
Standard deviation
Standard deviation is a widely used measure of variability or diversity used in statistics and probability theory. It shows how much variation or "dispersion" there is from the average...
in their positioning of 0.4m. The circle they describe is around 5m inside the monument's bank. Twenty-one of the holes remain unexcavated and no reliable dating material has been recovered from the other thirty-five. The only available carbon date from the holes comes from charcoal in one of the later cremations. It gives the broad range of 2919-1519 cal BC. That sarsen
Sarsen
Sarsen stones are sandstone blocks found in quantity in the United Kingdom on Salisbury Plain, the Marlborough Downs, in Kent, and in smaller quantities in Berkshire, Essex, Oxfordshire, Dorset and Hampshire...
stone chips have only been found in the upper fills of the excavated pits implies that the digging of the holes predates the megalithic phases of Stonehenge. From this stratigraphic evidence it is therefore likely that the holes were dug during the first phase of the monument, Stonehenge 1 (around 3100 BC) and were then reused for burials during Stonehenge 2 in successive centuries. By the time the standing stones of Stonehenge 3 were erected (around 2600 BC), the holes had fallen out of use.
The positions of the holes are today marked at the Stonehenge site by white discs laid in the ground surface. Archaeologists number them 1 to 56 counting clockwise from the later Slaughter Stone at the eastern side of the north east entrance. Hawley reburied the human cremations he found, placing them in the backfilled hole number 7. These remains were re-excavated in August 2008 as part of the Stonehenge Riverside Project
Stonehenge Riverside Project
The Stonehenge Riverside Project is a major AHRC-funded archaeological research study of the development of the Stonehenge landscape in Neolithic and Bronze Age Britain...
.
Theories about the holes
Many interpretations prefer an astronomical explanation for the purpose of the holes although this is by no means proved. It was thought that when the Aubrey holes were first dug, the only standing feature at Stonehenge was the HeelstoneHeelstone
right|thumb|250px|Southwest face of HeelstoneThe Heelstone is a single large block of sarsen stone standing within the Avenue outside the entrance of the Stonehenge earthwork, close to the main road . In section it is sub-rectangular, with a minimum thickness of 8 ft , rising to a tapered top...
, which marked the point of the midsummer sunrise, viewed from the centre of the henge. The Heel Stone is now attributed to Stonehenge 3 and was therefore not contemporary with the holes.
It has been suggested that the Aubrey holes were originally intended to be posthole
Posthole
In archaeology a posthole is a cut feature used to hold a surface timber or stone. They are usually much deeper than they are wide although truncation may not make this apparent....
s containing timbers or stones but this is uncertain. Analogous timber circle
Timber circle
In archaeology, timber circles are circular arrangements of wooden posts interpreted as being either complexes of freestanding totem poles or as the supports for large circular buildings-British Isles:...
s at sites such as Woodhenge
Woodhenge
Woodhenge is a Neolithic Class I henge and timber circle monument located in the Stonehenge World Heritage Site in Wiltshire, England. It is north-east of Stonehenge in the parish of Durrington, just north of Amesbury.-Discovery:...
have influenced this interpretation; the positioning of the Aubrey Hole circle relative to the earth bank and ditch at Stonehenge is reproduced at similar sites with rings of timber postholes. That the holes appear to have been filled soon after excavation and then possibly redug does not exclude the possibility that they held timber posts which were replaced intermittently. No evidence of postpipe
Postpipe
In archaeology, a postpipe is the term given to the remains of an upright timber placed in a posthole. Given the right conditions, timbers may survive over long periods of time and a recovered postpipe can simply be of solid wood...
s has been recovered with the holes although modern archaeological excavation techniques have not been applied to the pits. If the putative timbers were purposefully removed when they fell out of use, then even this evidence would be difficult to spot however. The lack of full documentation from the early Stonehenge digs in the twentieth century and the disturbance caused by the insertion of the later cremations during Stonehenge 2 have also added to the uncertainty over the function of the holes.
In a survey of twentieth-century excavations at Stonehenge, English Heritage
English Heritage
English Heritage . is an executive non-departmental public body of the British Government sponsored by the Department for Culture, Media and Sport...
's Stonehenge in its landscape
Stonehenge in its landscape
Stonehenge in its landscape: Twentieth century excavations by R. M. J. Cleal, K. E. Walker and R. Montague is an archaeological report on Stonehenge published in 1995...
, archaeologist Karen Walker collated and studied the surviving records from all the earlier work on the holes and concluded that "Although the evidence is inconclusive, and will no doubt be the subject of continued debate, the authors are inclined to support the view that the Aubrey Holes held posts, which were removed, rather than burnt in situ or left to decay."
In August 2008, further excavation of Aubrey Hole 7 by Mike Parker-Pearson, Mike Pitts
Mike Pitts
Michael Anthony Pitts is a former professional American football defensive end in the National Football League for the Atlanta Falcons, Philadelphia Eagles, and the New England Patriots. He played college football at the University of Alabama and was drafted in the first round of the 1983 NFL...
and Julian Richards
Julian Richards
Julian Richards FSA, MIFA is a British television and radio presenter, writer and archaeologist with over 30 years experience of fieldwork and publication.-Early career:...
led the archaeologists to suggest that the 56 holes held Welsh bluestones. Professor Parker-Pearson said: "It's very exciting that we have evidence for stones right from its beginnings around 3000 BC. That's almost 500 years earlier than anyone had thought."
Archaeoastronomy and the Aubrey Holes
The astronomical readings of the holes are largely a product of the interpretation of them as being simple pits without any structural features. This approach has required finding an explanation which tends towards the theory that the holes were repeatedly dug, filled and redug and excludes possibilities relating to any possible timber posts standing in them. The theory that they may have been used to hold temporary markers for use in astronomical observations gained credence in the 1960s.An early attempt to analyse the positions of the Aubrey holes was undertaken by Gerald Hawkins
Gerald Hawkins
Gerald Stanley Hawkins was an English astronomer and author most famous for his work in the field of archaeoastronomy. A professor and chair of the astronomy department at Boston University in the United States...
a professor of astronomy at Boston University
Boston University
Boston University is a private research university located in Boston, Massachusetts. With more than 4,000 faculty members and more than 31,000 students, Boston University is one of the largest private universities in the United States and one of Boston's largest employers...
in the 1960s using an IBM 7090
IBM 7090
The IBM 7090 was a second-generation transistorized version of the earlier IBM 709 vacuum tube mainframe computers and was designed for "large-scale scientific and technological applications". The 7090 was the third member of the IBM 700/7000 series scientific computers. The first 7090 installation...
computer. In his book Stonehenge Decoded, Hawkins argued that the various features at the Stonehenge monument were arranged in such a way to predict a variety of astronomical events. He believed that the key to the holes' purpose was the lunar eclipse
Lunar eclipse
A lunar eclipse occurs when the Moon passes behind the Earth so that the Earth blocks the Sun's rays from striking the Moon. This can occur only when the Sun, Earth, and Moon are aligned exactly, or very closely so, with the Earth in the middle. Hence, a lunar eclipse can only occur the night of a...
, which occurs on average about once a year on a 346.62 day cycle. Lunar eclipses are not always visible as the moon may be below the horizon as it moves across the sky, but over 18 to 19 years (18.61 years to be precise) the date and position of a visible eclipse will return to its beginning point on the horizon again. As the motion of the moon's orbit also causes it to work its way across the sky on an 18.61 year cycle in what is known as the journey between major and minor standstill and back, the theory that this period was both measurable and useful to Neolithic peoples seemed attractive. Lunar movements may have had calendrical significance to early peoples, especially farmers who would have benefited from the division of the year into periods which indicated the best times for planting. 18.61 is not a whole number and so it cannot be used to predict an eclipse without precision equipment and using only crude stones or timber posts in a circle instead. Hawkins' theory was that three 18.61 year cycles multiply out to 55.83 however, which is much closer to an integer
Integer
The integers are formed by the natural numbers together with the negatives of the non-zero natural numbers .They are known as Positive and Negative Integers respectively...
and therefore easier to mark using 56 holes. Hawkins argued that the Aubrey Holes were used to keep track of this long time period and could accurately predict the recurrence of a lunar eclipse on the same azimuth, that which aligned with the Heel Stone, every 56 years. Going further, by placing marker stones at the ninth, eighteenth, twenty-eighth, thirty-seventh, forty-sixth and fifty sixth holes, Hawkins deduced that other intermediate lunar eclipses could also be predicted.
More recent examination, notably by Richard Atkinson, has proved Hawkins largely wrong as it is now established that the different features at the monument that he tried to incorporate into many of his alignment theories were in use at different times and could not have worked alone. The lateness of the installation of the Heel Stone being the final nail in the coffin. Furthermore, the 56 year period is not in fact a reliable method of predicting eclipses and it is now accepted that they never repeat their date and position over three consecutive 18.61 year-long lunar cycles. Hawkins' theories also required strict observance of the phases of the moon which further complicated predictions using his model.
In 1966 Sir Fred Hoyle
Fred Hoyle
Sir Fred Hoyle FRS was an English astronomer and mathematician noted primarily for his contribution to the theory of stellar nucleosynthesis and his often controversial stance on other cosmological and scientific matters—in particular his rejection of the "Big Bang" theory, a term originally...
examined the arguments in favour of an astronomical purpose for the holes and concluded that the 28 day lunar cycle could still have been indicated by moving a marker stone representing the moon anticlockwise by two holes every day, ending up with 56 holes in total. By moving another marker anticlockwise two holes every thirteen days and which represented the Sun, an annual journey around the circle could also be made. Two further marker stones would also have had to be moved round three holes per year to represent the points where the moon (or rather its marker) crossed the Sun marker's path. Hoyle proved that this could have been used to produce a much more reliable method of predicting eclipse
Eclipse
An eclipse is an astronomical event that occurs when an astronomical object is temporarily obscured, either by passing into the shadow of another body or by having another body pass between it and the viewer...
s as whenever the moon and sun markers are directly opposite each other and the other two stones occupy those same opposing points, an eclipse can be guaranteed. This also has the additional benefit of not needing any standing stones to be present at the site.
Although less complex and romantic than Hawkins' 'stone age calculator' such a technique is certainly feasible if only in theory. Much more elaborate predictive practices have also been suggested for the holes although all these methods, including Hoyle's, require a high level of astronomical awareness and a grasp of some very abstract concepts including knowing where and when to first position the stones around the circle. It has also been pointed out by R. Colton and R. L. Martin that simpler methods exist, based on observing the position of each moonrise, which would have worked just as well and which would not require moving numerous markers amongst 56 holes. This diminishes the astronomical significance of the number of the Aubrey Holes and their circular arrangement and tends to suggest that any astronomical purpose for the site may have been no more than symbolic.
On astronomical symbolism several analysts from Gerald Hawkins to Anthony Johnson (ref. 3 ; pages 259-260) have noted that Plutarch ( in the Moralia, V) reported that Typhon / Seth in Egyptian and Greek myth was identified as the shadow of the Earth which covers the Moon during lunar eclipses. Plutarch further records that the Pythagoreans symbolically associated Typhon with a polygon of 56 sides. The connection of 56 to lunar eclipses is explicit.
Extra-astronomical interpretations
Mike Pitts has asserted that the Aubrey Holes did in fact originally hold timbers and compares the site at this stage to Woodhenge, The SanctuaryThe Sanctuary
The Sanctuary is a prehistoric site on Overton Hill located around 5 miles west of Marlborough in the English county of Wiltshire.It is part of a wider Neolithic landscape which includes the nearby sites of Silbury Hill, West Kennet Long Barrow and Avebury, to which The Sanctuary was linked by the...
and other Neolithic timber circles. Such a view contradicts the archaeo-astronomical view of the holes as being a unique predictive device.
In fact, early Stonehenge may have been barely different from the other Neolithic timber circle
Timber circle
In archaeology, timber circles are circular arrangements of wooden posts interpreted as being either complexes of freestanding totem poles or as the supports for large circular buildings-British Isles:...
s of the British Isles which had varying numbers of postholes and orientations and could therefore not have been used for in island-wide eclipse predicting. The interpretation of such timber circles is unclear, although parallels were drawn with Native American totem pole
Totem pole
Totem poles are monumental sculptures carved from large trees, mostly Western Red Cedar, by cultures of the indigenous peoples of the Pacific Northwest Coast of North America...
s by Stuart Piggott
Stuart Piggott
Stuart Ernest Piggott CBE was a British archaeologist best known for his work on prehistoric Wessex.Born in Petersfield, Hampshire, Piggott was educated at Churcher's College and on leaving school in 1927 took up a post as assistant at Reading Museum where he developed an expertise in Neolithic...
in a 1946 BBC
BBC
The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...
radio lecture. A 50 cm high carved wooden figure found in the Thames Marshes in 1912 and carbon dated to 2460-1980 BC has been used rather tenuously to support the theory of carved wooden posts serving a more terrestrial purpose.
Another possible explanation for the holes, suggested by Richard Atkinson, is that they were excavated in turn in some unknown ritual
Ritual
A ritual is a set of actions, performed mainly for their symbolic value. It may be prescribed by a religion or by the traditions of a community. The term usually excludes actions which are arbitrarily chosen by the performers....
involving a procession around the inside of the monument. Others have pointed out the significance of the 28 day human menstrual cycle
Menstrual cycle
The menstrual cycle is the scientific term for the physiological changes that can occur in fertile women for the purpose of sexual reproduction. This article focuses on the human menstrual cycle....
and argued that the holes may have been fertility indicators. Alexander Thom
Alexander Thom
Alexander "Sandy" Thom was a Scottish engineer most famous for his theory of the Megalithic yard, categorization of stone circles and his studies of Stonehenge and other archaeological sites.- Life and work :...
calculated that the circle of holes had been laid out in a circumference of 131 of his megalithic rods although this number has no known significance. A recent CAD study of the holes has shown that a fifty-six sided polygon can be generated by the simple use of square and circle geometry. Aubrey Burl also notes that the azimuth of the Heel Stone, beyond the Aubrey Circle, marks the mid-point in the swing of the Moon between major and minor standstill points, at 51.3 degrees.
The true purpose of the holes may never be known, although future excavation of the remaining twenty-four using modern archaeological techniques will certainly provide more information.