Vistas in Astronomy, Vol. 27, pp. 231-289, 1984 Printed in Great Britain. All rights reserved.
0083-6656/84 So.O0 +.50 Copyright © ]984 Pergamon Press l,td.
MEGALITHIC ASTRONOMY: THE LAST FIVE Y E A R S C. L. N. Rugglcs Computing Studics Unit, University of Leicestcr, University Road, Leiccster LE1 7RH. U.K.
ABSTRACT. Until recently, megalithic astronomy too often consisted merely of seeking out specific examples of astronomical alignments at particular sites and laying great emphasis upon them. Too little attention was paid to the question of whether the alignments could have arisen through factors quite unrelated to astronomy, and also to wider archaeological evidence about the sites involved. In recent years a more critical approach has emerged, both in discussions of individual sites and in statistical studies of groups of sites. Interdisciplinary collaboration has become more common, involving workers trained in the numerate sciences and those in the humanities. As a result, we are just beginning to see more reliable conclusions about astronomical observations in ancient times, and to see them interpreted in the context of current archaeological thought. At last, it seems, archaeoastronomy in Britain is starting to produce results of genuine interest to archaeologists and historians of astronomy alike. This paper attempts to review developments in megalithic astronomy since 1979 and to examine the topic in the wider contexts of world archaeoastronomy and of archaeology and anthropology in general.
I
!BI~g~W~I~g~
Ever
since
individuals significance pursuit
of
speculations recent
the have
earliest
antiquarians
sporadically
become
roamed the British countryside recording ancient remains, fascinated by the idea that there might be an astronomical
in many prehistoric monuments, and have dedicated large amounts of time and energy in this
idea.
with
Astronomer Norman Lockyer was perhaps the first to back up astronomical
accurate
measurements
(Lockyer 1909); and by f a r the most i n f l u e n c i a L name o f
decades has been t h a t o f e n g i n e e r Alexander Thom, who has p u b l i s h e d t h r e e books (Thom 1967;
1971; Thom & Thom 1978a) and a g r e a t many papers in a d i v e r s e c o l l e c t i o n
That are
f r e e - s t a n d i n g m e g a l i t h i c s i t e s - stone c i r c l e s nowhere near c i r c u l a r ) ,
menhirs
-
Firstly,
should megalithic
particularly to
known,
monuments.
can
:,v^~::,~
concentrate
easily
termed stone r i n g s , si nce many
rows o f t h r e e or more s t a n d i n g s t o n e s , stone p a i r s and s i n g l e s t a n d i n g
been
sites
interested
tended
and
have
(more c o r r e c t l y
of journals.
the focus o f almost a l l
have
o f t h i s work i s perhaps due t o two f a c t o r s .
s u r v i v e d the passage o f time p e c u l i a r l y
well:
in astronomy - h a r d l y ever w i t h any formal t r a i n i n g their
a t t e n t i o n upon these r e l a t i v e l y
thus i n v e s t i g a t o r s
i n a r c h a e o l o g y - have
conspicuous, and consequently w e l l -
Secondly, alignments along and between s t a n d i n g stones are e a s i l y p i c k e d o u t , be imagined t o be ' i n d i c a t i n g '
something: the idea t h a t such alignments i n d i c a t e d
231
232
C.L.N. Ruggles
horizon
astronomical
events
has dominated investigations of prehistoric astronomy, almost to the
exclusion of any others.
Thus,
over
become
many
years,
the concept of 'megalithic
astronomy'
has been born, and it has risen to
a vigorous field of enquiry as well as one attracting considerable popular interest.
has
been
far
in
much
talk of a 'megalithic culture'
advance
(1971:
ch.
of
I),
harbouring astronomical (and geometrical) expertise
its time and hitherto totally unexpected:
was
a
There
'Megalithic Man', according to Thom
competent engineer, had an extensive knowledge of practical geometry, and
studied the movements of the sun and moon in great detail.
In
fact,
as
archaeologist Graham Ritchie pointed out in his introductory talk at the 1981 Oxford
Archaeoastronomy tradition
Symposium
(Ritchie
is rather different.
1982),
the
archaeological
perspective
on
the megalithic
Our current vision of prehistoric societies in Britain depends not
only on the evidence of spectacular burial and ritual monuments, into which category the megalithic monuments clear
fall,
that
monuments
but
also on that from settlement sites, artefacts and environmental data.
It is
there was no 'megalithic culture' as such, and no 'Megalithic Man': instead megalithic of various types span a period of about four millennia, being built at various stages in
a long and complex period of social change, and are related to many independent traditions.
The
following outline of current archaeological thought is taken largely from Burgess (1980), with
embellishments fair
f r o m Whittle
representation of
hopefully
it
(e.g. 1981) and other authors. I t does not claim necessarily to be a
their
does at
least
views, give
and i t certainly touches upon many contentious points; but
the essential flavour of the archaeological background to the
megalithic astronomy debate.
Early
communities w e r e established in B r i t a i n and Ireland by about 3500 bc (uncorrected
farming
radiocarbon years), that is by about the end of the f i f t h millennium BC.
Their best-known funerary
monuments are the Long tombs, which were b u i l t of Large stones in the north and west, and of earth, timber,
turf
burials,
and
chalk in the south and east.
covered by a Large mound and sealed.
were accessible
after
collective
burial
millennium
BC.
groupings,
and with
The earthen Long barrows were used f o r one or two The megalithic Long tombs contained chambers which
t h e i r mounds were thrown up.
places, During
sometimes over this
period
These e a r l i e s t megalithic sites were used as
Long periods.
Their construction spanned the fourth
the population was widespread, organised perhaps in family
few Large focal centres; there seem to be few signs of stress or competition
f o r resources.
Around 2500 bc
(3000 BC)
there were sweeping innovations in material culture and in burial and
Megalithic Astronomy
ritual
practice.
In both the megalithic and non-megaLithic areas, Long communal tombs were grad-
ually replaced by round burial mounds - passage graves (including of
Ireland),
During
233
the vast ones in the Boyne Valley
round chambered cairns of a variety of forms, and round barrows in southern England.
this
period there are signs of population growth, and possibly of a concern to define t e r -
ritories
and
maintain
'public'
sites.
good relations with neighbours; there is evidence of social interaction at
The scale of some of these sites - the I r i s h passage graves, enormous earthwork
monuments such as Silbury H i l l in Wiltshire and the 9km-long Dorset cursus - implies that society at
this time was remarkably uell-organised, with powerful and capable ruling e l i t e s who could com-
mand and carry out vast undertakings. first
Amongst these public works of the t h i r d millennium were the
henges (earthwork c i r c l e s , sometimes containing rings of standing stones or upright timbers)
and large stone circles.
Midway through the t h i r d millennium there emerged the mysterious Beaker t r a d i t i o n , and also a major technical
innovation
- metallurgy. The Beaker is a fine, distinctive and eye-catching vessel. The
classic
'Beaker burial' consists of an individual crouched inhumation accompanied by a beaker but
rarely
with other grave goods, placed in a groove or cist beneath a small round barrow. For every
individual preserve of
buried
with
a
beaker, many more were buried without.
Beakers, i t seems, were the
of a privileged few: in other words they were some sort of status item.
Howeverthe idea
an invasion of 'Beaker f o l k ' from the continent, bringing new traditions and the s k i l l of metal
working, has currently fallen from archaeological favour: the Beaker t r a d i t i o n , i t is now generally felt,
marks social change which occurred throughout Britain around the middle of the third millen-
nium BC.
A
further
in
the
disruption occurred around 1750 bc, or the beginning of the second millennium BC.
Only
Wessex chalklands, where burials were prestigious and (for example) the Sarsen Stones were
erected
at
Stonehenge, does a r e l a t i v e l y stable, organised society seem to have endured, and even
reached i t s apex. Elsewherewe see the gradual demise of the great public centres, and increasing evidence
of
population appears
competition and
to
climatic
for scarce resources and great social division.
Social upheaval, rising
deterioration may a l l have contributed to an agricultural c r i s i s which
have come to a head about 1200 BC.
This f i n a l convulsion marks the end of a number of
long-standing t r a d i t i o n s , the megalithic one amongst them.
The
free-standing megalithic sites remaining from this general period of our prehistory are numer-
ous: there are something like a thousand stone circles alone surviving in varying states of repair. However these sites
are
notoriously d i f f i c u l t to date, since demonstrable associations with organic
remains are almost unknown. described span
a
above, that
I t is generally thought that they date to the later part of the period
is to the third and second millennia BC; but even so they almost certainly
considerableperiod in terms of culture change and represent a variety of d i f f e r e n t motiv-
ations and uses.
234
C.L.N. Ruggles
2.1
~£~g~j~
The megalithic astronomy debate has largely - indeed, until recently almost exclusively - been comprised of arguments about the interpretation of a few individual sites. of
Alexander
wholly
Thom,
themselves
disproptionate
involving
Even the extensive studies
numerous sites, continued until recently to generate a
amount of interest in just a few "classic" sites where particularly notable
astronomical alignments seem to occur.
There
are
many
elaborated logical it
is
those
in
pitfalls later
in
lavishing so much attention on so few sites, pitfalls which will be
sections
of this paper.
This is especially true where independent archaeo-
evidence relating to the astronomical hypothesis is either absent or ignored. informative cases
where
Nonetheless
briefly to examine recent debates about certain "classic" sites, especially in independent
archaeological evidence is available and has been brought to bear
upon the astronomical discussion.
Newgrange
is perhaps the least contentious example of a monument widely quoted as incorporating an
astronomical
alignment.
Built somewhat before 3000 BC, it is the largest of the vast Boyne Valley
passage graves. A 19m-long passage, with ample headroom for the visitor, leads from the entrance to a
large central chamber with a corbelled ceiling up to 6m high.
the
Three side chambers open out from
central one, each housing a stone basin which probably held the cremated remains of the people
for whom the tomb was built. The entire passage grave is surrounded by a circle of standing stones.
Newgrange covered the
was a
was sealed.
His own observations, followed up by a survey by Patrick (1974), estab-
that the sun's rays will enter the roof-box, penetrate the entire length of the passage and
illuminate -23o.0
Over the entrance to the passage he dis-
mysterious 'roof-box' which would have continued to admit light into the interior after
entrance
lished
excavated and restored by O'Kelly (1971).
the
central
chamber
and -25o.9 (Fig. I).
just
after
sunrise if the sun's declination lies between about
Thus direct sunlight reached the centre of the tomb every morning for
about a week on either side of the winter solstice.
Given t h a t s o u t h - e a s t e r l y o r i e n t a t i o n s for
other
the
presence o f the r o o f - b o x (not r e a d i l y e x p l i c a b l e o t h e r w i s e ) i n j u s t the r i g h t p o s i t i o n
shaft
of
reasons,
light
to
the p r o b a b i l i t y
are q u i t e common amongst passage g r a v e s , and may be f a v o u r e d
penetrate
the
of a chance s o l s t i t i a l
alignment i s a p p r e c i a b l y hi gh; however
e n t i r e passage has made i t s
accepted amongst a r c h a e o l o g i s t s and astronomers a l i k e .
intentionality
f o r the
almost u n i v e r s a l l y
FIG. 1. Plan and s e c t i o n a l After Patrick (1974).
box
profile
Roof
0 I
2 I
4 I
6 I
8 a
o f Newgrange, showing t h e p a t h o f d i r e c t
J
sunlight
10 J metres
after
--
dawn a r o u n d m i d w i n t e r
~ N
solstice.
o
r~
0a
236
C.L.N. Ruggles
Maes
Howe
was
built
around
2500
BE
and is the greatest of the Orkney tombs.
Its entrance is
oriented SW, and here the se~tjnQ sun's rays around the midwinter solstice illuminate the rear wall of the central chamber (Moir 1981). The stone that blocked the passage was not quite tall enough to fit
to
the
top of the entrance, and it has been suggested (Burl 1981a) that the shortfall was to
allow, as at Newgrange, the sun's light to enter the tomb after it had been sealed.
There on
are
some problems remaining at Maes Howe, and certain pitfalls in placing too much emphasis
apparent similarities between the two sites (see Moir 1981); however Newgrange and Maes Howe do
seem
to
provide evidence of astronomical observations as early as about 3000 BC which were incor-
porated into monumental architecture.
2.3 ~ O ~ O Q ~
Stonehenge,
being
astronomical these
such
a well-known monument, has attracted a grossly disproportionate amount of
attention, especially during the 1960s.
theories
ments here.
has
A detailed and balanced appraisal of many of
been given by Heggie (1981a) and there is no need to repeat the various argu-
Thankfully it seems that the tide of unwarranted speculation has abated quite markedly
in recent years.
The
only
reasonably uncontentious statement that can be made about Stonehenge is that the general
orientation sunrise of
of
the axis of the monument at various stages in its development is towards midsummer
and midwinter sunset, and that this may well have been deliberate.
at
A precision in azimuth
best a degree or two of arc is involved; the popular notion that the heel stone defined the
direction of solstitial sunrise more precisely is quite unsupportable, because the supposed observing position (the centre of the monument) can not be defined precisely enough on the archaeological evidence, and, even if it could be, the Heel Stone is too near to provide an accurate foresight and the horizon behind it is featureless.
The practice most common at Stonehenge has been to identify certain features at the site and to fit a
theory to 'explain' them.
uting
Even when this is done impartially there are grave dangers in attrib-
astronomical (and geometrical) frameworks onto what is a very limited sample of the original
features
at
the site, namely those which in 2000 AD are superficially obvious, those which happen
to have been excavated when large areas of the site are still unexplored, and so on. have
been
amply
expounded
These dangers
by Pitts (1981a; 1981b) in the context of the discovery of a possible
companion to the Heel Stone.
Some depend
of
the upon
most famous astronomical theories at Stonehenge (Hawkins 1963; Hawkins & White 1966) statistical
arguments
about
the number of astronomical alignments between pairs of
points chosen at possibly significant. These arguments fall down on many different grounds:
lack of
Megalithic Astronomy
~£J~ZJ
justification
237
for the points chosen in the first place, and archaeological doubts about
some of those that were (Atkinson 1966); numerical flaws in the probability calculation (see, e.g., Ruggles ion a
1981a); and, perhaps most importantly, the non-independence of data (e.g. when the precis-
of alignment being considered is only about one degree and the horizon is flat, a line between pair
of points indicating midsummer sunrise in one direction will inevitably indicate midwinter
sunset in the other).
It
is
truly
unfortunate
that
the topic of megalithic astronomy is so coloured by the excessive
attention that this one site, and some highly speculative interpretations of it, have received over the years.
Ballochroy 1954). 3.5m, The
has
been a source of debate ever since Thom first mentioned it in an early paper (Thom
It is a 5m-long three-stone row situated on the west coast of Kintyre.
The stones are some
3.0m and 2.0m in height, the last of the three appearing to have been broken off at the top. second
and third stones are slabs oriented across the alignment. Some 35m away, in the align-
ment, is a cist (Fig. 2a).
Thom Two
came to regard this site as one of the most important solar sites known to him (1971: 36-37). indications
at the site, the three-stone alignment and the wide flat face of the central slab
$2, point to horizon foresights behind which the upper limb of the sun would just graze at the summer
and
accurate
winter solstices respectively 'in Megalithic times' to
one or two minutes of arc.
(Figs. 2b & 2c), providing foresights
The existence of not one but two precise foresights, both
indicated at the same site, was seen as sure proof that they could not have arisen by chance.
Commentators sceptical of this interpretation, such as MacKie (1974), pointed out various problems. Firstly, slabs
the line along the stone row is not well-defined, precisely because two of the stones are
oriented across it; it may point anywhere in an azimuth range of some 10 ° or more.
The wide
face of the central stone is not perfectly flat, so that the qusetion of exactly where it points is open to interpretation: stone
may well have weathered and leant over somewhat since erection.
impressive this
it depends upon which part is used for doing the sighting.
because
orientation
its is
top
Furthermore the
Stone $1, although now less
has broken off, also has flat faces which point to a different peak;
without solar significance.
These observations suggest that the statistical
probability of the Ballochroy alignments occurring by chance may well be quite large, given all the implicit midwinter the view.
assumptions
which
have
been
made.
Finally the kist, which is on the line of sight to
sunset, would have been covered by a cairn in prehistoric times, and would have obscured
238
C.L.N. Ruggles
N To Corra Bheinn f
0,
3metres ,
A TO kist 4 - - ~ .....
ToCara ~ Island
J, 0 ....
about40m 4m
3.5m
J--
2m
1o-
B
30"
I
I
316°
317°
C +3
:I
"-.
I
222 ° FIG. 2.
223°
I
224 °
225 °
I
226 °
Ballochroy, Kintyre. (a) Site plan, after Thom (1971). (b) Midsummer sunset at 1600 B.C. behind Corra Bheinn, Jura (30 km). After Bailey et a~. (1975). (c) Midwinter sunset at 1600 B.C. behind Cara Island (12 km). After Bailey et a~. (1975).
Megalithic Astronomy
Because date
the
the
precision of the claimed foresights is only a minute or two of arc, it is possible to
two
foresights. would
alignments
to
within a century or two, assuming that they were used as solstitial
Bailey e~ a~. (1975) carried out a survey and concluded that a date of around 1600 BC
fit
suppose,
239
both, could
lending either
strong
support
to
the astronomical hypothesis.
The cairn, one might
have predated the stones and been levelled when they were erected, or else
not built until the stones had fallen into (astronomical)
disuse.
There
the debate rested, various opinions being expressed by different popular writers on the sub-
ject,
until
alignment two
Burl
66) uncovered a sketch of the site made in 1700.
This clearly shows an
consisting not only of the three standing stones and the cairn (still erect) but also of
further
predated
(1979:
cairns
the
and a further menhir.
stones.
Thus
it
The 'Great Cairn' is of an early type unlikely to have
almost certainly obscured the view throughout the lifetime of the
stones, and indeed did so until recent times.
Debates such as the Ballochroy one are never, it seems, settled once and for all. Thus astronomical enthusiasts
point
out that an observer in prehistoric times might have stood on the cairn to make
midwinter sunset observations. Burl himself (1983) maintains that the solstitial orientation of the alignment
was probably deliberate, but at a much lower level of precision: similar in fact to New-
grange
and
Maes
Howe.
Patrick (1981) points out that, if this were the case, the orientation of
stones
set at right angles to the alignment would approximately indicate midsummer solstice simply
because the azimuths of midsummer and midwinter sunset are roughly 90 ° apart at Scottish latitudes.
The story of Kintrau is one of the best-known in megatithic astronomy. The most conspicuous feature at the site is a 4m-tall menhir, whose flat faces roughly indicate a distant mountain notch ideally placed
as
a solstitial foresight accurate to a minute or two of arc.
The one problem is that the
view of the notch is obscured by an intervening mountain ridge. To avoid this Thom (1969) suggested that
observations could have been made from a ledge, which he thought to be artificial, on a hill-
side just behind the menhir (Fig. 3). The possibility emerged of an archaeological test upon a supposed astronomical site: was the platform indeed artificial?
MacKie surface.
(1974) duly
An analysis of the orientation and dip of the long axes of these stones showed that their
distribution MacKie
excavated the platform, and found a Layer of small stones beneath the present
appeared to resemble that in other known artificial layers more than in natural ones.
concluded
that this, together with circumstantial evidence from the excavation, left "very
little doubt that the Kintraw notch and platform together form an artificial construction".
240
C.L.N. Ruggles
N
S To notch
,.-..
Stream in
deep g o r g e ~
-.~,-=-,.-....'...'.'.-.-.i..Z . . . . . . .
~
...............
:~::::. large menhir I stone Despoiled cairn
Plan of Kintraw, Argyll, after Thom (1971).
The debate continues to the present day. MacKie
complete
-~,=. ~ ~ ~
~- 7 ~"~ .\ Ledge 5m higher than ground at cairn 30metres I
0 I
but
~ -
~ ~i~-~
/_~=~=_=
~
4m
FIG. 3.
~ ~ ( ~
. . . . . . . .
(1981:
lack
of
McCreery (1980b) cast doubt upon the petrofabric anaysis,
116) responded forcefully.
McCreery and others have also pointed out that the
human debris found during the excavation is very surprising if the platform was
used as the astronomical theory supposes.
MacKie (MacKie et a~.1984) now concedes that the Kintraw
evidence is inconclusive.
Another doubt has been cast by the assertion (Patrick 1981) that the distant notch cannot, in fact, be seen even from the 'observation platform': an intervening ridge just obscures it. 140-141)
simply
calls
MacKie (1981:
this a nonsense, and indeed the present author has seen the notch from the
platform; however a movement of less than 0.5m from the centre of the platform makes a crucial difference.
McCreery et a~. (1982) suggest that the disagreement may be accounted for by differences
in eye height of different investigators, differences in vegetation levels on the intervening ridge at
different
times of year, and differences in weather conditions altering terrestrial refraction
effects.
Perhaps the most teLLing o b s e r v a t i o n , although one only mentioned in passing by McCreery e t a ~ . , i s that
an
observer
view
the
notch.
first before
place, and
i.e. after
along the ridge t o the SE of the p l a t f o r m c e r t a i n l y would not have been able t o Yet such o b s e r v a t i o n s would have been c r u c i a l t o s e t t i n g up the s i g h t l i n e
in the
in determining the p o s i t i o n o f the p l a t f o r m , by making o b se rva t io n s o f sunsets the
solstice
(see Thom 1971: 13-14). This creates severe d i f f i c u l t i e s
t h e o r y t h a t Kintraw represented a h i g h - p r e c i s i o n s o l s t i t i a l
sightline.
f o r the
Mega]ithic Astronomy
The
site
at
Brainport
Bay, which has been uncovered in recent years, is an important one in the
context of the megalithic astronomy debate. natural has
outcrop
izon
It is a complex involving an alignment of features - a
which has been paved and terraced, two large boulders and a 'back platform' which
also been artficially modified (Fig. 4).
distant
241
The alignment is oriented to the NE towards the only
horizon visible from the site - at the far end of Loch Fyne.
would
mark
the
upper
A notch on this distant hor-
limb of the rising sun at about a fortnight either side of midsummer
solstice.
Excavations nearby,
by Gladwin, described by MacKie (1981), uncovered two sockets in the main outcrop and,
two
small
'observation
stone
boulders'
slabs into which they fitted well.
As viewed from the boulders, dubbed
by MacKie, the shape of the outcrop frames the distant notch and the slabs,
if erect, would have resembled 'the sights of a huge rifle' pointing at the notch.
Subsequent
excavation
(MacKie
e~
~!- 1984) established C-14 dates around 1400 Be, and uncovered
more
specific evidence of human occupation such as scatters of flint flakes.
site
was
The
not,
it
'observation
At the same time the
seems, primarily intended for domestic, defensive, industrial or funerary use. boulders'
have, however, been in place since well before Neolithic times. Their
presence might be explained by the chance discovery in Neolithic times of a site suitable for rough orientation
towards midsummer solstice.
MacKie's subsequent work uncovered evidence of a further,
equinoctial, alignment at the site, again involving man-made features and a horizon notch.
The
site
hypothesis is
is
important
of
perhaps
solar
there
exist archaeological data which appear to corroborate the
constructions oriented upon solar phenomena.
misleading:
high-precision
because
he sees his work as a successful archaeological test of the hypothesis of
observations
observation
(and
MacKie's own interpretation, however,
using natural foresights.
hence Thom's solar calendar)
He insists that the idea of high-precision is supported.
In fact, the structure orien-
tations at Minard are in themselves insufficiently precise, and the two notches respectively do not fall
exactly
could
well
at have
the solstice or at the 'calendrical'
equinox (Thom 1967: oh. 9).
The alignments
been only rough, and the notches on the horizons indicated are in positions that
might easily have arisen by chance.
3.1 !h~ ~
~! !bemi~ ~ ! Q ~
In
contrast to these discussions of individual sites, arguably the most important evidence presen-
ted
over the years by A. Thom (and later by A. Thom & A.S. Thom) arises from analyses of groups of
FIG. 4.
I J >,.:o:.:-" ::::::::::: • A
main alignment
l
0
r
!
1
i
i
I
5m
i
observation boulders
N
,
Trench
Plan of Mtnard (Brainport Bay), Argyll, after MacKie (1981).
E x c a v a t e d area Rock outcrop Stone s o c k e t s Standing stone A r t i f i c i a l bank
Back platform
Back platform
Observation boulders Rock
Lower terraces
Kerbs
Notch Rear stone .~
Main Outcrop
Front stone Turf
~n
00
("3
r,o
sites taken together.
Megalithic Astronomy
243
The evidence is cumulative in nature.
At each stage in the work it consists
essentially of one or more analyses of many putative indications from a number of megaLithic sites, and
at
stage
each
stages.
the level of precision of indication being tested is greater than at previous
The later work concentrates on lunar sightLines. Four distinct stages have been identified
by the current author (Ruggles 1981b) as follows.
~
5- In his earliest work Thom measured the declinations indicated by 72 structures at 39 mega-
lithic
sites,
plotting
results in the form of a probability histogram, or "curvigram" (Thom
1955:
Fig.
1967:
Fig. 8.1).
B.1),
the only difference being that rising and setting lines are not distinguished.
of
these
solar, are
8).
the
This evidence was later extended to 262 structure indications at 145 sites (Thom The 1967 curvigram is replotted in Fig. 5 from Thom's original data (1967: Table
curvigrams
lunar
and
and
On the basis
associated statistical tests Thom suggested the existence of deliberate
stellar alignments set up to a precision of about half a degree.
Accumulations
evident around the solar solstices, equinoxes and intermediate declinations representing equal
division
of
the
year
into
8
and
maybe
16 parts; and also around the four declinations which
represent the extremes of the moon's Limiting monthly motions in its 18.6-year cycle - declinations referred
to
by Thom as the lunar 'standstills'.
Further accumulations are interpreted by Thom in
terms of stellar alignments at particular dates.
~
2-
itial
declinations,
Lower
Limbs were preferentially observed; the further analysis of the lunar lines (ibid.: ch. 10),
of
In 1967 Thom analysed further those Level 1 indications which fell near the solar solst-
which
about the
there
about
are
about
10 minutes of arc. four
declination
30
of
them (Thom 1967: ch. 9), and found evidence that the upper and
40, suggests the same thing. This increased the inferred precision to
The results for the lunar Lines are shown in Fig. 6a, which superimposes
intervals
centred upon the mean lunar standstills, and reproduces the data
considered by Thom.
6~
~-
horizon
In his Later work Thom considered an effectively distinct hypothesis, namely that distant features
themselves Because two
merely
such
as
served
notches to
provided natural foresights, and that structures at the sites
identify the observing position and which foresight was to be used.
of the accuracy of any individual foresight,
declinations can now be quoted to a minute or
of arc, and the idea of sightlines of much higher precision can be tested.
distant
The analysis of 40
horizon features at 23 sites (Thom 1971: ch. 7) suggests the use of distant foresights for
observations accurate to 3' or better, and to record the 173-day, 9' perturbation in the moon's motion (Thom 1971: ch. 2; see also Morrison 1980). The resulting curvigram is reproduced in Fig. 7a.
~eve~ 4. The a n a l y s i s at Level 3 took no account o f small v a r i a b l e c o r r e c t i o n s t o the d e c l i n a t i o n s , such
since
as
variable parallax.
1978
(Thom
&
Thom
At Level 4, represented in t h r e e papers by Thom and his son A.S. Thom
1978b; 1980a; A.S. Thom 1981) each sightline was considered on its own
244
C.L.N. Ruggles
('2D ('U
(N)
I
<
V
<
~
-
Lr? __kY? I
<
<-
Q
?
<
Lc? I
I
nd I
I
FIG. 5.
8.8
0
i
I
J
8S
S
J
b
I
i
i
f
3@
I
18
I
f
i
J
3S
iS
i
]
48
'Curvigram, of declinations indicated by 262 structures at 145 sites. Thom's original data (Thom 1967: Table 8.1) is used. This graph differs from Thom's own (1967: Fig. 8.1) by not distinguishing between rising and setting lines.
'
t
o 0 a
246
C.L,N, Ruggles
m e r i t s , t a k i n g i n t o account the time o f year and time o f day o f presumed use, va rio u s small c o r r e c t i o n s being made a c c o r d i n g l y . In a d d i t i o n , the data set was r e s t r i c t e d t o those few Lines the Thoms considered t o be most convincing on the ground. cut
than
The r e s u l t i n g curvigram peaks are even more c l e a r -
at previous l e v e l s , and when the a n a l y s i s i s r e f o r m u l a t e d in a more rig o ro u s way as sug-
gested by Morrison (1980), the s i g h t l i n e s seem so accurate ( t o b e t t e r than a minute of arc) t h a t i t seems they
could
only have been set up at the end o f an averaging process Lasting some 180 years
(A.S. Thom 1981: 38).
There
have
1981)
f o r example has drawn a t t e n t i o n t o the great v a r i e t y o f types o f s i t e ,
and
been
methods
have
s~e
a
of
number
of c r i t i c a l
assessments o f the data a t d i f f e r e n t
f e a t u r e s in common w i t h one a n o t h e r ) .
has
Moir (1980;
geographical Location
i n d i c a t i o n found in the data at Level 1 ( s i t e s used in a s i m i l a r way would s u r e l y He has a lso h i g h l i g h t e d se ve ra l s i t e s where a r c h -
a e o l o g i c a l evidence makes the proposed astronomical i n t e r p r e t a t i o n p a r t i c u l a r l y (1979)
levels.
doubtful.
questioned the e f f i c a c y of several of the s i t e s in the sample at Level 3 as h i g h - p r e c -
i s i o n Lunar i n d i c a t o r s , t h a t is how c o n v i n c i n g l y they £ou~d have served t h i s purpose. have
pointed
sites,
out
which
indicated
(1980a)
t h a t s e l e c t i o n d e c i s i o n s as t o which data t o analyse in the f i r s t
potential
-
justifiable
McCreery
are on
indicating
subjective
and
devices
at each s i t e ,
t h a t the p a r t i c u l a r
a 2Ejo£~ grounds.
Many authors place - which
and which h o rizo n f e a t u r e s taken t o be
s e l e c t i o n d e c i s i o n s made by Thom may not be
F i n a l l y some commentators, most n o t a b l y Heggie (1972), McCreery
and Ellegaard (1981), have pointed out t h a t lunar o b s e r v a t i o n s o f the p r e c i s i o n claimed a t
Levels 3 and 4 simply may not be f e a s i b l e in p r a c t i c e .
Thorough
reassessments
of
the
evidence at each o f the f o u r Levels have been attempted in recent
years by the present a u t h o r , based upon f i r s t - h a n d examination o f each o f the s i t e s in question and upon
resurveys
where
appropriate.
The r e s u l t s o f t h i s work are described in more d e t a i l
in the
sections that f o l l o w .
The
principal
questions
to
be
answered
in
order t o reassess Thom's data at t h i s
l e v e l are as
follows.
How ence
~#
~
E~2~O ~g~ ~ 2 ~ £ ~ 2 0 ~
site List
The sequence o f s i t e reference numbers in Thom's r e f e r -
(Thom 1967: Table 12.1) - A l / 1 , A l / 2 e t c . - shows t h a t f o r each s i t e included some-
t h i n g l i k e two o t h e r s , which were present in an unpublished s i t e L i s t , were missed o u t . We must ask why
other
s i t e s which were v i s i t e d were found u n s u i t a b l e f o r surveying and i n c l u s i o n .
reasons would c l e a r l y be u n r e l a t e d t o t h e i r astronomical p o t e n t i a l , bad a s t a t e of r e p a i r f o r a survey t o be w o r t h w h i l e .
f o r example i f
Legitimate
they were in t o o
Megalithic Astronomy
~g~ ~z~ 92~o~!g! io~i~l~o~ ~ ! ~ tion criteria were adhered to. two
slabs
~ ~U
~i~l
zn a n
247
early analysis (Thom 1955) rigid selec-
Thom considered only indications defined by an outlier to a circle,
in line, or a row of three or more stones.
In the 1967 analysis, however, there are no
such clear-cut selection criteria, and there are a number of instances where astronomical lines may have been preferentially selected.
For example, at some sites only the indication one way along an
alignment has been included, and not the other. It is possible that such decisions were unwittingly based upon one line being astronomical and not the other.
~Z~
~£~
~[~g~gJ£~
~!0~9~!~!~0~
i O ~
~
~
gQ~QZ
If so, these require iden-
tification and removal.
~
~
~RO~J2~
2~ b
Z ~
C ~
JO ~ J ~
~J~l
About 20% of the 1967 data consist of
sightlines to what are considered to be indicated horizon foresights, tains. not
In these cases we are often not told what the claimed method of indication is; we are often
told
other
what
the
equally
foresight
is; and we are never told how wide the indication is, and how many
prominent and well-indicated horizon foresights might equally well have been chosen
as putative foresights by the investigator. are an
such as notches between moun-
being
confused.
astronomical
What is happening here is that two distinct hypotheses
One is that structures on the ground, such as stone rows, themselves provide
indication, and that the actual shape of the horizon they point to is irrelevant.
The other is that natural horizon foresights provide the astronomical sightline, and all the structure on the ground has to do is to point out - preferably uniquely - which foresight is to be used. If
the
two
hypotheses
are tested in the same analysis there is a danger that our decision as to
whether a given putative sightline is considered to be of the 'indicated foresight' type may depend upon
a
consideration of the declinations yielded by the two hypotheses; the choice can clearly be
influenced by the astronomical possibilities.
!~ !b~mi~ ~r~!~m~o~ 2! 2£~J~!~ ~rrgr~ Q Q S g ~ that
a
fixed
Thom used fixed widths for his gaussian humps, so
uncertainty was assigned to each indicated declination regardless of the nature and
present
state of the indication.
certain
within
wide
bounds,
Where the direction of the original structure orientation is un-
this
means
that a subjective decision was made as to the original
probable indication. This decision might unwittingly have been influenced by astronomical considerations.
In
order
to
considered be
invoked.
indications
answer the first of these questions it is insufficient simply to revisit those sites
by Thom.
Some overall strategy for identifying and selecting sites for analysis has to
In order to answer the second point it is also insufficient merely to remeasure those recorded
by Thom.
A code of practice for selecting potential indications needs to be
laid down and strictly adhered to at each site encountered.
248
A
C.L.N. Ruggles
surveying
finally
programme
western
Scotland was begun in 1975 with these points in mind.
completed in 1981, and the results were published in 1984 (Ruggles 1984a).
progressed, it
in
was
a
It was
As the project
reassessment of Thom's work was no longer seen as the principal aim of the project;
more an attempt to lay a new methodological framework for assessing alignments of possible
astronomical
significance
at
ancient
sites.
The project and its results are described in more
detail in Section 4.2 below.
The
evidence at Level 2 for lunar indications of a precision of about 10' depends upon the reality
of the bimodal shape of the cumulative probability curve in Fig. 6a. the
curve
is just as good, a Level 1 explanation will suffice.
If a unimodal (Normal) fit to
A reassessment of the evidence at
Level 2 was undertaken in 1979 and published two years later (Ruggles 1981b: Section 4.3). eight
Thirty-
indications were identified in Thom's original list (Thom 1967: Table 8.1) as comprising the
data of possible lunar significance.
An
archaeological reappraisal was attempted first.
Three sites were identified whose authenticity
is in serious doubt, and a further four where there is some doubt. found
to
involve else
be dubious on archaeological grounds in other cases too.
The astronomical hypothesis was Four indications were found to
chambered tombs or cairns, putatively functioning either as backsights to be stood upon or
as
likely
artificial foresights to be viewed from another site some distance away. elements
usually
define
Cairns make un-
in astronomical alignments of this precision, because their construction does not a
position
anywhere
near accurately enough.
The "room for manoeuvre" open to a
present-day investigator looking for astronomical alignments is illustrated by the fact that a further on
line top
in the sample involved sighting towards a menhir when standing adjacent to (rather than
of)
standing
a
large
megalithic
chambered cairn. sites,
and
these
Only 24 putative indications in the sample involved freewere a diverse collection, comprising rows, pairs, single
menhirs, circles and circles with outliers drawn from a wide geographical area. status of different lines (reasonable,
somewhat dubious and very dubious)
The archaeological
is indicated by differen-
tial shading in Fig. 6a.
A
reappraisal
tions not
simply
the efficacy of the sites as lunar indicators revealed that 6 of the 38 indica-
could
not work at all in the manner claimed.
At one site the claimed horizon could
in fact be seen from the structure postulated to be indicating it; and in the other five cases
indications seem
of
corresponding to Thom's description could not be found.
impressive
now
were
Two further indications which
once merely an undistinctive part of a more complex structure - in one
case a pair of stones are all that remains of a stone circle.
The outcome of these reappraisals was that only 19 of the original 38 lines seem at all reasonable;
Q
FIG. 6.
O0
i
Level 2 analysis and reassessment. (a) Curvigram based on Thom's data, but with archaeological status indicated by differential shading. (b) Remaining indications after an additional reappraisal of the efficacy of the putative indications. of the lines is indicated by differential shading, the most reliable being the darkest. (c) Revised indications after reassessment and resurvey. The horizontal scale is in degrees. After Ruggles (1981b).
S)
Again, the status
~o
~ o
o
250
C.L.N. Ruggles
seven
are
somewhat
dubious
ruled out altogether.
for
one reason or another, six are very dubious and six more can be
The resulting effect on the declination curvigram is shown in Fig. 6b.
When
lines of reasonable status are considered alone, virtually all trace of the double-peaked structure disappears.
The final stage in the reassessment was to resurvey the sightlines trying to treat indications in a demonstrably indicated
unbiased
way.
declinations,
The biggest problem, it was found, was that the accuracy quotable for
given
the
nature of the indication and its present state of repair, was
often considerably greater than the standard error quoted by Thom. In many cases there seemed to be no a ~ o £ ~
reason for selecting the particular declination value quoted by Thom. In the reassessed
curvigram, different standard errors (i.e. different gaussian hump widths) were assigned to different indicated declinations in order to reflect this.
The results are shown in Fig. 6c.
No signif-
icant trace remains of the double-peaked structure.
It
was
lunar
concluded that the data provided by Thom does not, in fact, provide reasonable support for observations
bimodal
of the precision implied by Level 2.
However Thom stated (1967: 165) that the
shape came as a complete surprise when he first plotted the graph; thus, as Heggie (1981b:
$23) has pointed out, this consideration could have had no influence on the selection of the lines. It
was
hoped
that the large-scale Level 1 project, when completed, would provide fresh data with
which to resolve this issue.
3.4 ~ Q ~ S ~ m ~
The
evidence
the
proximity
gets.
~ ~S~
at Levels 3 and 4 depends upon the precise distribution of indicated declinations in of
particular astronomical "targets" (the mean lunar standstills)
about those tar-
The question of the selection of sites themselves, and of potential indicating structures at
those sites, is thus of minor importance compared with the selection of horizon features for inclusion as potential foresights.
A reassessment of the evidence at Level 3 was carried out alongside that at Level 2 described above (Ruggles curvigram
1981b:
Section
(Fig. 7a).
4.4).
Forty
putative sightlines were identified as contributing to the
Peaks are evident at deviations of 2, ~ + A
stills, where s is the lunar semidiameter and
and s - ~
from the mean stand-
A is the amplitude of the 173-day perturbation.
In fact, astronomical considerations should immediately raise our suspicions about this result: for even to
if the 173-day wobble was observed, the 180-year cyclical variation in these declinations due the
wide.
ellipticity
of the moon's orbit should in fact blur out these points over a range some 6'
(A fixed parallax correction was applied to this data by Thom at Level 3.)
;©
--
i. /
FIG. 7.
I ; Jr_
(~0 _-
\\
~\ =
(
,
.
Level 3 analysis and reassessment. (a) Curvigram based on Thom's data. (b) Remaining indications after reappraisals of their efficacy. Indicated foresights are shaded; unindicated foresights are unshaded. Untenable indications have been removed. (c) Results of an analysis of all horizon notches and dips indicated by structures for which a single 'indicated foresight' was included by Thom. Classes of horizon feature are indicated by differential shading, the best being the darkest. the horizontal scale is in arc minutes. After Ruggles (1981b).
~ ~
LF]
;JJ"
J
~ ~
5
}l ' ~ ,
(L
._ . - - ~ ~ _ _ _ _ ~
Q
:~.
c~
252
C.L.N. Ruggles
The
hypothesis being tested at Level 3 is that a sightline consists of a horizon foresight such as
a prominent notch, together with a structure marking an observing position (behind it) and pointing to the foresight. When the sites in question were visited it transpired that one foresight was nonexistent
and a further five could not be seen at all from the positions from which they were meant
to be indicated. An example is the line to the south at Callanish in Lewis - the foresight, amongst mountains on Harris some 26 km away, is obscured by a local outcrop just 50m to the south. A further 19 of the 40 claimed foresights are not in fact indicated by any artificial structure at all, or else the supposed indication is not genuinely prehistoric or is some degrees off line. This fact is not
clear from Thom's accounts (1971: Chs. 5 & 6). A typical example is Beacharr in Kintyre, a 5m-
tall
menhir
claimed
with
its longer sides oriented roughly parallel to the shore by which it stands: the
foresight,
however, is out to sea on Jura, where there is a fine selection of notches for
the investigator to choose from as putative foresights: without restriction, since none is actually indicated. The 'psychological devastation' which results when a tentative convert to high-precision megalithic astronomy first encounters a site such as this has been described by Gingerich (1981).
In Fig. 7b we have omitted the non-existent foresight and the five which cannot be indication; is
the unindicated foresights are left unshaded.
largely
formed by unindicated foresights.
unindicated
lines,
let
those
seen
from
It is clear that the main peak at s +
the A
The fact that a peak shows up at all amongst so few
alone so prominently, is tantamount to proof that Thom simply included in
his
analysis
horizon features that fitted the anticipated declinations in the first place.
This
simply
that
this selection effect did occur are manifest in accounts by the Thoms of their site procedure
backs up the variable parallax argument for thinking the same thing.
Some indication
(e.g.A.S. Thom 1981: 24). It is clear that if a horizon feature was found, by site measurement, to yield an astronomically significant declination, then it was considered by the Thoms as a candidate for
a deliberate foresight, whereas if it did not, it was not so considered.
justified,
in
The Thoms felt quite
view of the existing conclusions at Levels 1 and 2 when this later work was carried
out, in proceeding in this manner.
Amongst the 15 remaining f o r e s i g h t s in the Level 3 a n a l y s i s , i t es,
sides of h i l l s l o p e s ,
least
one
actually the
or
analysis
and
because
considered out
foresights.
In a l l
but t h r e e cases, t h e r e were a t
two, and o f t e n s e v e r a l , o t h e r contenders f o r i n d i c a t e d f o r e s i g h t s adjacent t o those
included in the s t a t i s t i c a l
ground
carried
knobs, dips and shoulders o f h i l l s .
was found t h a t t h e r e e x i s t e d n o t c h -
a n a l y s i s : these o t h e r f e a t u r e s were e q u a l l y w e l l - i n d i c a t e d on
at Least as prominent as the chosen ones, but were a p p a r e n t l y not included in t h e their
significant
d e c l i n a t i o n s did not correspond t o any o f the Lunar p e r t u r b a t i o n extremes by
Thom.
Fig. 7c shows the r e s u l t s o f an independent a n a l y s i s which was
as p a r t of the reassessment. A~
such
features
which
Only notches and dips were considered as candidates f o r could
equally well have been indicated by the suggested
indications on the ground were surveyed and included on the graph. peaks are now evident.
It is clear that no significant
Megalithic Astronomy
A
253
reassessment of the evidence at Level 4 was completed in 1981 and has been published recently in
two
parts
1981)
(Ruggles
1982a;
1983a).
The data set used by the Thoms (Thom & Thom 1980a; A.S. Thom
consisted of all indications they considered to have been reliably measured - a total of 42.
Detailed
reasons
were given by A.S. Thom (1981: Appendix 1.1) why indications included in earlier
analyses
were not now suitable.
Of these 42 lines, 23 were amongst a sample of 25 examined separ-
ately in an earlier paper (Thom & Thom 1978b) as being most convincing according to strict terms of reference. of
In both analyses, the calculated residuals between measured and expected declinations
lunar significance were less than 2'.
The reassessment considered all 44 lines included in one
or other of the Thoms' analyses.
3.5.1 ~ E ~ 2 f l ~ E ~ lines,
both
indications,
Z ~ J ~ -
on
the
and
by
basis
As
at earlier levels, an attempt was made to classify the 44
of archaeological knowledge about the structures forming the putative
considering
the
efficacy
of the structures as high-precision astronomical
indicators.
Three
of the three indications can, it seems, be ruled out as intentional.
Orkney)
the
In one case (Stenness,
archaeological structures forming the indication predate its date of supposed use, as
deduced from the positions of the structures themselves, by some 1500 years; in the second (Callanish, to
Lewis) the proposed foresight cannot in fact be seen from the structure which is hypothesized be indicating it, a situation which is clearly absurd; and in the third (Skipness, Kintyre) the
backsight is not a genuine archaeological site.
In
a
further
other
words
entirely
14 the
cases the azimuth range indicated misses the proposed foresight by up to 50; in indication,
unindicated,
if deliberate, was only rough. Thirteen more foresights are in fact
although
two
are indicated from another position from which they are also
postulated to have been observed.
Only
14
of
remaining
the 44 putative indications, it transpires, actually represent cases where structures
today
accurately indicate the proposed horizon foresight.
One of these (Dunskeig, Kin-
tyre) is however very dubious on archaeological grounds - the two stones forming the indication may well represent the grounders of a former field wall. Brogar,
Orkney)
(Corogle a
former
relatively idually,
involves
a
barely
discernible
A further three are somewhat dubious: one (at mound
of
uncertain artificial status; another
Burn, Forfar) involves two large irregular stone blocks which are possibly the remains of field
wall,
and the third (Stillaig, Cowal) involves a menhir which is very possibly a
modern trackway marker. seem
geographically,
reasonable spanning
The remaining ten putative indications, when considered indiv-
enough on archaeological grounds; however as a group they are scattered the
Scottish
Highlands
from Orkney to Kintyre, with only three fairly
254
C.L.N. Ruggles
close together in Argyll and one far-flung addition in Dyfed.
Furthermore they represent a diverse
collection of indicating structures: a line of three mounds, four alignments of menhirs, a cairn to a menhir, a menhir to a cairn, a stone setting to a stone circle, and two flat sides of single menhirs.
In other words even the most convincing sites do not manifest any archaeological coherence.
3.5.2 ~ 9 ~ J ~ E ~ the to
44
~E~O~J~9~-
During 1979 and 1981 all the relevant sites were visited, and 38 of
indications were resurveyed.
within
about
This produced general agreement with the Thoms' declinations
I', but also confirmed the contentions of other authors (e.g. Patrick 1979) that
measured declinations are in fact only reliable to about I', owing to uncertainties in astronomical refraction and other factors.
3.5.3 Z ~
~2[~J9~
equally
plausible
statistical selves fell At
~0~ ~E
~J£
J~gO-
A study was undertaken of how many horizon features,
se as foresights, might equally well have been chosen for inclusion in the
analysis.
A classification system for horizon features developed by the Thoms them-
(Thorn & Thom 1980b) was used as the basis for this study, and it was noted whether features directly
within
an 'indicated azimuth range' or within 5° in azimuth on either side of one.
sites where surveys were possible, a total of 161 candidates were uncovered, compared with only
37 selected by the Thoms.
3.5.4 ~he Q ~ Z ~ calculated
2~ ~gOQ~ ~ E ~ J ~ Q ~ 2 9 ~ -
the
'measured'
The methods were then scrutinised by which the Thoms had
deviations
(B) and the 'expected' deviations (Q) from the mean lunar
standstill declinations. In calculating
6-values, it transpired that implicit assumptions had been
made about the value of a terrestrial refraction correction (the 'graze effect') and about the date of use of the site. In calculating the Q-values, implicit assumptions had been made about the particular
lunar
measured
event
and
postulated
expected
to
have been observed.
deviations had to be reformulated, so as to eliminate implicit assumptions
which could vary from sightline to sightline.
The
Q-values
noted
that
observed.
for the
Thus the entire method of calculation of
particular standard
The Thoms' calculations were then reworked.
Lunar events a c t u a l l y vary from one s t a n d s t i l l
t o the n e x t .
d e v i a t i o n o f t h i s v a r i a t i o n was f a r in excess o f the r e s i d u a l s
Analysis showed t h a t i t
would n o t , even t h e o r e t i c a l l y ,
I t was m6 - ~1
be p o s s i b l e t o achieve such small
r e s i d u a l s by o b s e r v a t i o n - even a f t e r an o b s e r v a t i o n programme Lasting some 200 ye a rs.
3.5.5 S ~ a ~ j s ~ a ! resents
[ea~cajsa~
For each s i g h t l i n e a r e s i d u a l
16
- ~1 can be c a l c u l a t e d which re p -
the d i f f e r e n c e between the measured d e c l i n a t i o n and t h a t expected f o r a given lunar e v e n t .
Even i f questions of data s e l e c t i o n have been adequately r e s o l v e d , a t t a c h i n g s i g n i f i c a n c e values t o small be
residuals
exaggerated
different
depends upon a number of hidden f a c t o r s . (i.e
Those quoted by the Thoms were found t o
the hypothesis of d e l i b e r a t e i n d i c a t i o n s a r t i f i c i a l l y
means, as f o l l o w s .
strengthened) by t h r e e
Mega ii th i c As tronomy
(i) ~ O ~ E ~ g ~ -
255
We must test whether observed declinations within a given 'band' centred on a lunar
standstill declination in fact cluster about targets within that band. ing
this
width used
hypothesis
must
For the purposes of examin-
a bandwidth must be assumed, and all observed data falling within this band-
be included.
The Thoms' statistical test assumes a bandwidth rather greater than that
in selecting the data; thus data towards the edges of the bands will be absent and clustering
about targets (towards the centre of the band) will be exaggerated.
(ii)
IQZQ~
E~O~J~£~-
In testing whether the data clustered about certain target values, the
Thoms considered six possible targets in each 'lunar band'. In fact, nine targets occur within each band.
The
subset
of
six chosen by the Thoms are not those inherently most likely to have been
observed; the only criterion seems to have been that the fitted the data best in the first place.
(iii) of
Da~e the
i.e.
When
9~ 9J~ ~0~ J 9 £ ~
terrestrial
their
~
refraction
-
The mean date o f use o f the i n d i c a t i o n s and the mean val ue
'graze effect'
(Thom & Thom 1978b: 174) were deduced from the d a t a :
values were a d j u s t e d t o f i n d those which f i t t e d
best.
these factors are taken into account, the small residuals obtained by the Thoms are no Longer
significant.
This is true even when only the data selected by the Thoms is taken into account.
3.5.6 Summa£~.
The
argument for very high-l~recision lunar indications can, it seems, be convin-
cingly challenged on any one of four different grounds.
These are
(i) archaeological; (ii) theoretical
(astronomical),
i.e. what is actually possible;
(iii) by examining the selection of data; and (iv) by reassessing the methods of statistical analysis.
When
all
four
factors are taken together the evidence is overwhelmingly against deliberate lunar
indications of very high precision.
4.1 ~ c ~ d ~ E t j ~ Q
Two
recent p r o j e c t s i n v o l v i n g the p r e s e n t a u t h o r have attempted t o examine groups o f s i t e s as Thom
did, but paying paramount attention to the demonstrably unbiased selection of data. statistical
tests
on
the
data
obtained
The aim of any
is then simply to compare the observed distribution of
indicated azimuths and declinations with that expected given random structure orientations. two
differ
significantly,
we
may investigate possible causes.
If the
One of them is that astronomical
considerations affected the orientations of some of the structures in the sample.
256
C.L.N. Ruggles
The result of a statistical test on any particular accumulation of data is a simple overall answer: a
probability that random orientation can account for the distribution of declinations or azimuths
observed.
If this probability is very small, we must ask whether the non-randomness can be accoun-
ted for by any non-astronomical hypothesis; if not, we are forced to accept an astronomical explanation.
In this case, and at this stage, we can return to the data in more detail and investigate
possible
variations in astronomical precision with site type or geographical location, in the hope
of
correlating
evidence
on
variations in astronomical orientation with other facets of archaeo-
logical evidence about the sites.
Before
there
is
any point in carrying out a statistical test, we need to accumulate enough data,
and from a sufficiently promising group of sites, to give a reasonable hope of a definitive result. We
immediately encounter the problem of finding a suitable data sample.
and of
attempts problems
span or
One approach follows Thom
to examine a variety of free-standing megalithic sites: there are, however, a number in doing this.
Firstly, they almost certainly represent a variety of motivations and
a long period in terms of culture change.
Secondly, many of them are of a design (e.g. three
four stones, not in llne) which does not suggest any overridingly important candidates for ast-
ronomical stones
indications.
having
Thirdly,
vanished
without
some of them are doubtless partially destroyed, further standing trace.
Finally, some may not be genuinely prehistoric, such as
single standing stones erected in more recent times as trackway markers, boundary stones or cattlerubbing posts.
In
the
tive of
almost total absence of helpful archaeological evidence (such as radiocarbon dating, rela-
chronology extant
and excavated artefacts)
relating to these sites, a rigorous statistical analysis
structure orientations provides a possible means of isolating trends of interest.
from 'misleading' sites will simply add to the background noise. Level
1,
however,
there
If it were not for Thom's work at
might seem little hope of isolating any overall trends, astronomical or
otherwise, amongst such a diverse group of sites. do
Data
Motivated by Thom's work a project attempting to
this was conceived by the present author and three colleagues in 1975.
It is described In Sec-
tion 4.2 below.
An
alternative approach might lead us to seek a group of sites that are demonstrably similar arch-
aeologically, so as to avoid most of the problems about selecting sites for consideration. Ideally, the group would be well-defined and confined to a given geographical area, yet sufficient in number to provide a reasonable set of data. In addition, we might seek sites with a design such that (say) one
direction
at each site is clearly of special importance.
the problems about selecting possible 'indications'
The close
Recumbent to
this
In that case we would avoid most of
at each site.
Stone Circles (RSCs) of eastern Scotland and south-western Ireland (BurL 1976) come ideal.
In and around Aberdeenshire about one hundred certain or possible RSCs are
Megalithic Astronomy
257
known, about half of which are in a reasonable state of preservation, confined to an area some 80 x 50
km.
At each site the line joining the centre of the ring and the centre of the recumbent stone
provides
an obvious principal axis.
A new study of the Aberdeenshire group was undertaken in 1981
by the author in association with H.A.W. Burl, and is described in Section 4.3 below.
4.2 6 ~
~!ggx Rf ~QQ ~
4.2.1Z~ ~ & ~ i ~
~! ~ i ~
~f~h
~
f~f s~iQ~r~!!~
In preparing a list of sites for initial consideration, three problems immediately arise: (I) Which types of feature should be included? (II) What combinations of features comprise a site? (III) Which
geographical
areas
should
be considered and how should a list of sites within these
areas be compiled? The following scheme was proposed.
~I~.
Only monuments consisting of free-standing megaliths were considered - i.e. stone rings, set-
tings,
alignments and single standing stones - as opposed to those standing stones erected as part
of more complex architectural structures, such as orthostats and peristaliths of chamber tombs.
~I~. sites If,
A
SITE
of
was defined as any collection of megalithic rings, standing or fallen menhirs and
menhirs,
however,
two
such that each of these features is within 300m of at least one of the others. features are separated by a sea channel, or natural rises in intervening ground
level prevent them being intervisible, then the features were counted as separate sites.
~I~
Most
of the western Scottish islands and mainland Argyll were considered.
The region is
one in which Thom's work has been particularly extensive.
An
initial
the
site llst, comprising 322 reported sites, was compiled (Ruggles 1984a: Table 2.1) from
various
reference lists available.
It included all reports of free-standing megalithic sites
by each of the following five sources: (i) Thom's full site list, unpublished elsewhere; (ii) the Ordnance Survey Archaeological Record cards; (iii) the
relevant
inventories of the Royal Co~mnission on the Ancient and Historical Monuments of
Scotland; (iv) Burl's "The Stone Circles of the British Isles" (Burl 1976); (v) "Discovery
and Excavation in Scotland".
new discoveries.
This is an annual publication containing reports of
258
C.L.N. Ruggles
Most
of
the
322
sites were visited between 1973 and 1981, often more than once. On the basis of
these first-hand examinations, together with the descriptions and interpretations of other authors, 133
of
the
related
sites were dismissed from further consideration on various grounds, none of which was
to their possible astronomical significance.
grounds.
Seventy-five were excluded on archaeological
Forty-seven of them are highly dubious contenders for prehistoric sites. They consist of
natural
rocks and stone settings, more modern structures such as enclosures and shielings, and the
like. In the remaining 28 cases there is convincing evidence that the sites were not constructed as free-standing such
as
megaliths.
Most of them apparently represent the remains of more complex structures
megalithic chamber tombs.
A small number represent natural boulders which have been cup-
marked.
Of
the remaining 247 sites in the initial List, 43 were excluded from further consideration on the
grounds
that
either
been
original
their
exact
completely
positions,
(original) position could not be determined.
destroyed
or
(in
Thirty-one of these have
the case of single menhirs) removed intact from their
which can only be established with varying degrees of certainty.
(Re-erected
menhirs were included in this category, unless their original position was determined by excavation prior
to re-erection.)
of
the
12
sites
In order to avoid making decisions from site to site about the reliability
original position, all such sites were excluded from further consideration. could
not
be
The remaining
located, or else had previously not been located by other sources and no
fresh attempt was made to do so.
Every effort was made to visit all sites, however remote. in
the initial llst (mostly on small islands) could not be reached, either through lack of time or
sufficient in
However seven of the remaining 204 sites
the
funds,
lists
and were not considered further.
Another six sites were only recently included
of the Ordnance Survey and RCAHMS, coming to light during fieldwork concurrent with
that of the project, and were also not considered further.
Finally, the
the sites at Kintraw and Minard in Argyll (described in Section 2 above) were excluded on
grounds
that
they had both been excavated with a view to testing an astronomical hypothesis,
rendering the statistical approach irrelevant. Thus 189 sites were finally considered for analysis.
4.2.2 Zb~ m~&~ign ~ l!ogi~i2oml
Where at
we
each
making and
are deali ng w i t h a v a r i e t y of s i t e c o n f i g u r a t i o n s , very g r e a t care is needed in d e cid in g s i t e what c o n s t i t u t e s an o r i e n t a t i o n worthy o f c o n s i d e r a t i o n .
a s e r i e s of i n d i v i d u a l d e c i s i o n s in the f i e l d ,
might
selection
be
influenced
process
similar sites.
by
our
We must at a l l
costs avoid
d e c i s i o n s which might vary from s i t e t o s i t e
own p r e d i l e c t i o n s and p r e j u d i c e s regarding astronomy. Our data
must ensure t h a t we include (or r e j e c t ) s i m i l a r alignments from a r c h i t e c t u r a l l y
Megalithic Astronomy
A
259
preliminary set of selection criteria was developed and tested at the group of sites around Cal-
lanish,
Lewis
(Cooke et a~. 1977). They were subsequently modified, in order to take account both
of new types of site which were encountered, and of criticisms by other authors (e.g. Heggie 1981a: 141; 1981b: $19). and
then
The ideal is that such selection criteria should be Laid down prior to fieldwork
adhered
to strictly. In practice, modifications take place and data may be discarded or
extra data found to be required after a field visit. As the project evolved, some sites were revisited
and resurveyed in order to acquire additional data.
dilections
However in order to be certain that pre-
about particular sites did not influence this process, no reduction work was undertaken
on this project until the entire fieLdwork had been completed in 1981.
The
selection criteria
ed:
they
while
at
amidst the site
must
enough t o cope w i t h each d i f f e r e n t
a l s o be j u s t s u f f i c i e n t l y
a
welter
are
to
significant
of data which i s p a t e n t l y i r r e l e v a n t
following selection criterion:
t o the h y p o t h e s i s .
"the orientations of all
might be s i g n i f i c a n t .
However now consider a c i r c l e
omical . o r i e n t a t i o n
problems,
virtually
i n t o an o r d e r o f p r e f e r e n c e .
e x i s t e d at any p a r t i c u l a r such
as
procedure
unknown, or p a r t i a l l y
all
at
sites
where
we
find fallen
for
these
situations
that
scale, might,
One p o s s i b i l i t y
stones whose o r i g i n a l
another
conceivably,
have
i s t o a t t a c h Lower s t a t i s t i c a l
been i n t e n d e d .
is
cases, the code o f p r a c t i c e must c a t e r
t o g i v e equal l i k e l i h o o d t o the f u l l originally
position
In o r d e r t o p r e v e n t
weight t o i n d i c a t i o n s
or dubious s t o n e s , a n o t h e r t o g i v e them a lower c l a s s i f i c a t i o n
and
signif-
There are a number o f a s s o c i a t e d
submerged stones which may or may not be f a l l e n menhirs.
also.
would have us
structures for deliberate astron-
s i t e were then c o n s i d e r e d .
L e f t t o make s u b j e c t i v e judgements in i n d i v i d u a l
ation
likely
at the
Only those s t r u c t u r e s w i t h the h i g h e s t c l a s s i f i c -
being
fallen
At a s i t e c o n s i s t i n g o n l y o f two
w i t h o u t a doubt o f no p a r t i c u l a r
our
involving
two s t a n d i n g stones at a
o f 20 s t o n e s : the c r i t e r i o n
icance. The code o f p r a c t i c e adopted attempted t o c l a s s i f y
that
tines joining
As an example, c o n s i d e r
as these are the most obvious ways i n which an o r i e n t a t i o n
i n c l u d e from the s i t e some 380 o r i e n t a t i o n s ,
ation
evidence t o be submerged and l o s t
be i n c l u d e d in the a n a l y s i s ( i n both d i r e c t i o n s ) " . i s a good c r i t e r i o n ,
type o f s i t e e n c o u n t e r -
s e l e c t i v e so as t o p r o v i d e enough data f o r the a n a l y s i s ,
the same time not a l l o w i n g any p o t e n t i a l l y
menhirs t h i s site
must be f l e x i b l e
on the c l a s s i f i c -
range o f d e c l i n a t i o n s o r azimuths
A combination o f the second and t h i r d
o p t i o n s was f a v o u r e d .
Various selection criteria orientations rows
of
possible
interest
at a s i t e o f any p a r t i c u l a r
form.
t h r e e o f Bore stones were g i v e n the h i g h e s t c l a s s i f i c a t i o n ,
indications order
of
were d e f i n e d in o r d e r t o determine o b j e c t i v e l y
to
produced take
by the f l a t
account o f f a l l e n and dubious s t o n e s .
between stones in the c i r c l e indications
sides o f s i n g l e sl abs the l o w e s t .
o r between c i r c l e
formed by v i e w i n g one s i t e
what c o n s t i t u t e s t r u c t u r e In b r i e f ,
i n d i c a t i o n s al ong
between stone p a i r s n e x t , and Adjustments were then made i n
I n d i c a t i o n s i n v o l v i n g stone c i r c l e s
c e n t r e s and o u t l i e r s )
from a n o t h e r ( " i n t e r - s i t e "
were not c o n s i d e r e d . indications)
Horizons c l o s e r than 1 km, however, were excluded from c o n s i d e r a t i o n .
(either Finally,
were a l s o examined.
260
C.L.N. Ruggles
Most
statistical
independent
of
tests all
will
the
assume that each item of data (indicated azimuth or declination)
rest.
Thus there should be no direct relation between two items of data
which holds regardless of whether or not the structure orientations are random. are
is
If both directions
considered along a particular structure orientation or inter-site line, then this condition is
clearly near
violated.
to
minus
concerned). preference
We would obtain indications with azimuths exactly 180 ° apart and declinations
each
other (although this would depend upon the altitudes of the horizon profiles
On the other hand, there is rarely any a E ~ i ~ ! reason for choosing one direction in to
the other, and both indications mus~ be considered.
the data, once recognised,
Fortunately this inadequacy in
is easily allowed for when implementing statistical tests.
On the other
hand a different way in which non-independent data can arise, and one rather more difficult to deal with, is if too many alignments are considered between the same points (cf. Stonehenge).
This prob-
lem was avoided by the careful choice of selection criteria.
Surveys
were
of
weather conditions, were calculated from Ordnance Survey maps.
bad
undertaken between 1973 and 1981, and the remaining horizon profiles, missed because A total of 130 on-site and
146 inter-site indications were produced for analysis.
4.2.3 ~ ! ~ i ~
~8~!~-
We wish to test whether the indicated declinations observed are consis-
tent with random structure orientations. hypothesis
is
non-uniform,
no simple test was available and Monte-Carlo simulations were used in
order to assess significance levels.
The
This was done as follows.
property to be randomised is structure orientation, and the property we wish to investigate is
the indicated declination. pends of
Because the expected distribution under the null (random)
not only upon the indicated azimuth, but also upon the latitude of the site and the altitude
the indicated horizon.
which
We immediately hit a problem here because the indicated declination de-
Furthermore we are actually interested in an indication of finite width
will include a range of declinations. Thus the width of the indicated azimuth range (IAR) is
relevant, and also the shape of the horizon. Each of these other properties needs to be distributed in exactly the same way amongst the simulated data as it is amongst the observed data.
Each of the 276 indications has an associated latitude, altitude, IAR width and profile shape. simplification taken
as
values these
was
made:
it was assumed that all horizon profiles were flat, with their altitude
the mean of the actual altitude range within the IAR.
for data
latitude, are
altitude
sufficient
One
for
and IAR width. us
This gives 276 sets of associated
When combined with the azimuth of any indication,
to calculate the declination at both ends of the IAR.
These
declinations will represent the limiting indicated declinations except in those cases where the IAR includes
due
north or south (in which case one of the limiting declinations must be calculated at
the north or south point).
Megalithic Astronomy
In
26]
order to generate a set of simulated declinations three lists were produced, containing respec-
tively the 276 values of the latitude, altitude and IAR width for the observed data. Two were shuffled
randomly;
then the first entry from each list was recombined, then the second, and so on, so
as to produce 276 new latitude-altitude-width triplets. To each triplet was now assigned an azimuth selected set
at random, and the limiting declinations were calculated for the simulated indication.
of
276
ations
declination
have
observed
been
data.
intervals produced in this way will satisfy the requirement that orient-
randomised,
but that all other properties reflect exactly those present in the
To generate further simulations two of the three lists were merely reshuffled and
the process repeated.
We
One hundred simulations were produced in this way.
can now identify any 'target window' of declinations, and calculate the number of 'hits' scored
by the observed data upon that target. many or
A
We ask (i) in how many of the 100 simulations were there as
or more hits upon this target? and (ii) in how many of the 100 simulations were there as many fewer
hits upon this target?
The answer to question (i), expressed as a percentage, gives the
significance level at which the null hypothesis can be rejected in favour of this target being preferred; question (ii) expresses the significance level in favour of avoidance.
If we are to be completely objective we should avoid the trap of concentrating upon certain declinations known to be interesting in terms of celestial phenomena, and look for evidence of clustering about (or
an~
declinations.
Furthermore since we do not know how precisely any given orientation was
might have been intended to be) set up, we must test for a range of possible precisions.
Thus
we must look at a comprehensive range of declination windows of varying centres and widths.
The we
problem
is that we are now effectively considering some hundreds of different hypotheses, and
must lower accordingly the significance level at which we are prepared to reject the null hypo-
thesis
in
favour
of
any one of them. The precise amount by which we should do this, however, is
uncertain. Freeman & Elmore (1979) have noted the problem, but we still lack the theoretical framework
to deal with it in a rigorous way.
avoided the null
by
(i)
In the case of the western Scottish sites the problem was
only taking an interest in significance levels less than about I% and (ii) adding
rider that the only formal statement that can be made is that if we can confidently reject the (random)
hypothesis in favour of any of the alternatives presented, it is in favour of those
picked out in this manner.
4.2.4 As tzgngmj~a ~
~9~
manifested
at
trends
~Q~J~-
The statistical analysis of the 276 indicated declinations
three levels of precision.
-15 ° and +15 ° are strongly avoided.
At the lowest level, declinations between about
This reflects a general preference for structures to be orien-
ted N-S, NW-SE or NE-SW rather than E-W.
At
t h e second l e v e l ,
t h e r e i s a marked p r e f e r e n c e f o r s o u t h e r n d e c l i n a t i o n s
between -31 ° and -19 ° ,
262
C.L.N. Ruggles
J ~
(-
I
l
I
(
C~
fSD I
~J
o
ST I
I
I
I
0~
@I I
I
S
$2
"(e~86L) se166n~ J e ~ V " u ° ~ e o ~ s s e l o ~se46~4 e4~ o~ 6uLpuodseJJO3 6uLPe4 s ~se~Jep e4~ a6uLpe4s le~ueJe#~Lp Xq paL#~U6LS SL suo~e3Lpu~ #o uo~eoL~Lsselo aq~ "sa~Ls 4 s ~ o 3 5 uJe~Se~ 6g~ ~e suo~euL13e p pa~eoLpuL ~o =eJSLAJn3
82
8
"~ " 9 ~
264
C.L.N. Ruggles
and of
for
northern declinations above +27 ° . Since the majority of the data represent opposite pairs
indications
sequence
of
along
the
the
other.
same structures, one of these trends is almost certainly a simple conThe southern range very closely matches (i.e. matches to within about a
degree at either end) the range of declinations between the two standstills (i.e. the range of declinations range
which
the
corresponds
moon
can reach at the southern limit of its monthly motions).
The northern
(again to within about a degree) to those declinations to the north of any ever
reached
by the moon (or sun).
effect,
then this implies that structures were preferentially oriented upon the southerly limit of
the
If the southern trend represents the cause and the northern one the
moon's motions in a particular month. a
This need not have involved nightly observations of the
moon
in
given month, but could have been achieved simply by observing the rising or setting of
the
full
the
cause and the southern one the effect, then this implies that structures were oriented prefer-
moon nearest to the summer solstice.
entially
to
point
ever rose or set.
If on the other hand the northern trend represents
farther along the horizon to the north than the moon (or consequently the sun) Statistical analysis of the data as a whole can not formally distinguish between
these two possibilities.
At
the
most
precise level, there is marginal evidence of a preference for six particular declin-
ation values to within a precision of one or two degrees. Three of the declinations (-30~ +18° and +27 ° )
may
indicate
a
specific interest in the lunar standstills, and would imply that organised
observations were undertaken over periods of at least twenty years. However there is no evidence of any
interest in the other lunar standstill declination (-19°.5).
is -25 ° , and may indicate an interest in the winter solstice. ticular
The fourth preferred declination
The fifth value (-22°.5) has no par-
solar or lunar significance and the last (+33 °) is well outside those declinations attain-
able by the sun or moon.
Although the
there
winter
equinoxes
is
clear evidence of lunar orientation, and marginal evidence of orientation upon
solstice, (indeed,
there
is
no evidence whatsoever for an interest in the summer solstice or
declinations in the vicinity of the equinoxes are strongly avoided).
No evid-
ence was found of astronomical orientations of a precision greater than about one degree.
The
curvigram in Fig. 8 displays the new results in a form that can be compared with those of Thom
(Fig. 5).
Differential shading denotes the classification of indications, the darkest shading cor-
responding
to the highest classification.
to
the
assess
It should, however, be emphasized that it is misleading
significance of peaks purely on visual grounds, because of the non-uniform pattern
that would be expected even with random structure orientations.
4.2.5
!~
certain ular
~i~
i~g!~=
Perhaps the most interesting result to emerge from the project was that
coherent groups of sites featured predominantly amongst the indications falling in partic-
"preferred"
declination intervals.
These were sites in Mull and mainland Argyll in general,
Megalithic Astronomy
265
and the 3-, 4- and 5-stone rows in these areas in particular. No significant azimuth or declination trends
were
detected amongst sites in the Outer Hebrides or those in Jura and Islay.
No evidence
was found of any significant trends amongst inter-site indications.
A
closer
marked
declination
pairs the
examination of the rows, pairs and single flat slabs in Mull and mainland Argyll reveals trends.
Twenty-seven structures (13 alignments, 3 aligned pairs of slabs, 3
and 8 single slabs) are oriented in the south upon a declination which the moon can reach at southern
aligned
limit
pair
sideration slabs)
its
monthly
motions.
At a further fourteen structures (4 alignments, 1
of slabs, 2 pairs and 7 single slabs) the southern indication was excluded from con-
because
remain
tion"
of
the horizon was nearer than 1 km.
of
A mere ten structures (4 pairs and 6 single
which six represent cases where there is special reason to believe the "indica-
to be spurious.
None of the exceptions is a stone alignment.
The results are summarised in
Figs. 9(a) and 9(b).
The
exclusion
bears
upon
from
the
consideration of horizons closer than I km leaves us lacking vital data which
lunar hypothesis.
However it brings unwittingly a considerable bonus: the oppor-
tunity to test that hypothesis at a future date on "fresh" data.
There
is
no c o n c l u s i v e evidence f o r h i g h e r - p r e c i s i o n s t r u c t u r e w i t h i n the sout her n l i m i t i n g
range. The d i s t r i b u t i o n moon's
southerly
within
the
observed.
o f the 27 i n d i c a t e d d e c l i n a t i o n s
range).
However t h e r e i s some i n d i c a t i o n t h a t more p r e c i s e phenomena might have been
Alignments i n M u l l and m i d - A r g y l l appear t o be p r e f e r e n t i a l l y
and
ments range,
upon the "major s t a n d s t i l l "
Ouncracaig and Dunamuck I i n A r g y l l .
slabs in K i n t y r e and southern KnapdaLe are p r e f e r e n t i a l l y
which may i n d i c a t e an i n t e r e s t
o r i e n t e d upon the sout her n
moon). The s i t e s i n v o l v e d are Q u i n i s h , B a l l i s -
Dervaig S in M u l l , and B a r b r e c k , K i l m a r t i n ,
and
towards the
monthly Limit at random times w i t h i n the 1 8 . 6 - y e a r cycl e (a s i n u s o i d a l v a r i a t i o n
Limit of the range ( i . e . cate
is consistent with orientation
lunar
ALign-
o r i e n t e d i n the middle o f the
not i n the moon but i n the w i n t e r s o l s t i c e .
The p r i m a r y can-
d i d a t e s are A r d p a t r i c k , B a l t o c h r o y , Beinn an T u i r c , C l o c h k e i l , Mingary and KnockstappLe. The o r i e n tations
in
the v i c i n i t y
o f -19 ° are a more motley c o l l e c t i o n ,
i n c l u d i n g the a r c h a e o l o g i c a l l y dub-
ious s i t e s at U l u v a L t , Mull and Ounskeig, K i n t y r e (see S e c t i o n 3.5.1 above). The a c q u i s i t i o n ditional
of a d -
data from the s i t e s w i t h Local southern h o r i z o n s may help us t o decide whether any o f the
higher-precision
phenomena
are
real.
A study o f the Longer axes o f s i n g l e r e c t a n g u l a r stones i n
Kintyre, many of which failed to meet our criterion to qualify as slabs, might also be worthwhile.
4.3.1 ! ~ and
~ 2 ~
2~ ~ -
Recumbent stone c i r c l e s
are r i n g s o f stones a l l
o f which stood u p r i g h t
a p a r t from one a n o t h e r , w i t h the e x c e p t i o n o f one ( u s u a l l y by f a r the l a r g e s t stone) which Lay
on i t s
side f l a n k e d by two u p r i g h t s .
N i n e t y - s e v e n s i t e s were noted as c e r t a i n ,
p r o b a b l e or p o s s i b l e
266
C.L.N.
Ruggles
6
S
4
3
DuschW
2
qRC-'Yt_L
1".c S I ..~ggon
/
@
9
+
e i
~ 010~In3~
QKI 1 ,~.G'L. ~
• D u n c e s CG ~Q
Id
,-n,T o r b h ~ t " } E ~.f 9unstuck I ' s q~ hn 3i:3~ o O o k C ;~ t : I / '
"~IQu~O.mucl~
rT
(.
8
1
7
6
+
S
4
3-
8-
A
c
o
I
i -
°~7"'"~'° -i
~@ ,_
I
,
I
I
!
I
1
~8
3
4
S
6
:7
8
9
8
FIG. 9.
m i--1 0 o [] m I-- 2 3 - 2 2 -21 - 2 0 - 1 9 -18 -17 -16 -15
J I
03
Sites in Mull and mainland Argyll and their astronomical significance. (a) Map showing the distribution of stone rows (large dots), pairs (small dots) and single slabs (small circles). (b) Southern declinations indicated at the sites, where the horizon is not less than 1 km distant.
DECLINATION
Carse Quinish m [] Avinagillan Dunamuck I Kilmartin II Barbreck B Duncracaig Kilmartin m Escart m ! Dervaig $ Balliscate m Knockstapple i [] Branault Ballochroy m Duncracaig Beinn an Tuirc t Rowanfield i Ardnacross ClochkeU Mingary Ardpatrick Duachy Uisken Dunamuck II Cillchriosd Dunskeig Uluvalt Gruline Kilmory - 3 3 - 3 2 -31 - 3 0 - 2 9 - 2 8 - 2 7 - 2 6 - 2 5 - 2 4
0
,10
268
C.L.N. Ruggles
RSCs
by
Burl (1976: Appendix 1).
vation, upon
When a site has been destroyed or is in a poor state of preser-
whether it is in fact a good candidate for an RSC will be debatable: decisions will depend
the
(where
interpretation
known,
Lesser
greater
or
reason,
sites
unlikely
deduced
of descriptions by antiquarians, the situation of the site, its diameter or
quoted in the past) and the like.
Such decisions inevitably involve a
degree of subjective interpretation by the present-day investigator.
were
For this
classified independently by Ruggles (1984b) as certain, probable, possible or
candidates
for
RSCs
on
the
basis
of first-hand inspection and reference to original
sources.
During
the
listed
by Burt, with the exception of 18 quoted by Burl as destroyed.
cases
the
fields
summer
site
of
1981
visits were attempted to each of the 70 certain and 24 probable RSCs
could not be located at the given grid references.
In four of the remaining 76 A further eight sites were in
under crop and could not be approached for further study, leaving 64 that were successfully
examined.
4.3.2
~J~J2g
~
~J~b ~ =
~2~z--°D ~ J ~ D ~
With only two exceptions, all the sites visited
were found to be located on flat ground, hill tops or south- or southeast-facing slopes. This could reflect a preference for non-nearby horizons to the south and east, and so wherever a site was Located and accessible, a "horizon scan" was carried out. This consisted of dividing horizon distances into four categories: A (up to 1 km), B (1 - 3 km); C (3 - 5 km) and D (over 5 km). The horizon was then
scrutinized,
nearest degree.
The
most
south.
with
the azimuths of junctions between different categories being noted to the
The results are shown in Fig. 10.
obvious
trend t h a t emerges is a d i s t i n c t
The percentage o f horizons in category A drops from near 30% around due n o rt h t o under 5%
around
due
south.
The preference against nearby horizons i s not symmetrical about t h i s minimum,
but instead extends towards the e a s t . 10%
preference f o r non-nearby horizons towards the
between
evidence
The p r o p o r t i o n o f horizons in Category A does not r i s e above
azimuths o f around 60° (ENE) and 230 ° (SW).
that
At the same t i m e , t h e r e i s no convincing
t h e r e e x i s t e d a preference f o r very d i s t a n t ,
as opposed t o moderately d i s t a n t ,
hor-
izons in any p a r t i c u l a r d i r e c t i o n .
4.3.3
~£~D~!~
have
produced
clear
that
omical
2~ plans
~
B~-
Various authors have quoted valueS f o r RSC o r i e n t a t i o n s , o r e l s e
from which they can be measured.
On c l o s e r e xa m in a t io n , however, i t
becomes
there are at each s i t e not one but two candidates f o r a primary o r i e n t a t i o n o f a s t r o n -
significance,
and t h a t surveys by previous authors had sometimes confused the two.
One i s
the
Line from the centre of the s i t e through the centre o f the recumbent stone (the "Centre L in e " )
and
the
dicular either
other
is the l i n e p e r p e n d i c u l a r t o the longest a x i s o f the recumbent stone (the "Perpen-
Line"). Line,
At any p a r t i c u l a r
site,
depending on i t s present s t a t e , i t
is possible to define
or both: and where only the L a t t e r e x i s t s , t h i s has o f t e n been presented as the f o r -
~ZIMUTH RELATIVE TO PRINCIPALAXIS
~,ZIMUTH (ABSOLUTE)
0
10
20
3O
40
50
6O
7O
80
100
--80
10o
:IGS' 10 (UPPER) & 11 (LOWER). Aberdeenshire Recumbent Stone C i r c l e s . FIG. 10. Horizon scans by azimuth. For each 1 i n t e r v a l in azimuth we p l o t the percentage of horizons in d i f f e r e n t distance c a t e g o r i e s . A (0 - 1 km) bLack; B (1 - 3 km) dark shading; C (3 - 5 km) l i g h t shading; O (over 5 km) unshaded. A f t e r Ruggles (1984b). FIG. 11. Horizon scans f o r azimuths r e l a t i v e to the 'perpendicuLar' axis of s i t e s . Shading as above. A f t e r Ruggles (1984b).
70
°°t
8O
10o
LO-
20
30
40.
50.
60'
70,
80
IO0
rt
¢3
r~
270
C.L.N. Ruggles
mer.
However
at sites where both exist it can be seen that the long axis of the recumbent stone
often appears to have been set considerably off the line tangential to the ring, and the two orientations were
may
differ
considered,
by almost 20 ° . In the analysis both the Centre and Perpendicular orientations
and
they were analysed separately.
In each case the data set consists of those
sites where the axis in question can be defined.
Surveys
were carried out at sites examined during the summer of 1981 wherever the condition of the
site merited it. dicular
Line
Inevitably there were uncertainties in defining either the Centre Line or Perpen-
azimuth,
their magnitude depending upon the state of the site.
In the former case,
where a ring is circular and several stones remain in situ, the RSC centre may be accurately definable, but otherwise a good deal of subjective interpretation may be involved. Where there exists an internal
cairn or ring cairn this may influence the decision: if this is placed away from the ring
centre
we may have to decide which "centre" is the appropriate one, and if too few stones exist to
define
a centre we have to decide whether to take the position of an internal feature as such.
the
case
axis
of the Perpendicular Line the accuracy of the orientation of the assumed recumbent stone
will
exact
depend
upon how regular its shape is and whether it has moved.
The decision as to the
position of the centre of the recumbent stone, which is relevant to both the Centre and Per-
pendicular azimuths, also depends upon its shape and where the assumed ends are taken. is
In
it
were
possible quoted
to
reliably to define either axis to an accuracy of 1 ° or better. 0o.5,
Thus seldom
Measured azimuths
but in the majority of cases this figure is subject to considerable uncer-
tainty for one reason or another.
In
a
number
Perpendicular stones
of cases it is not possible to determine even an approximate value for the Centre or Line
azimuth.
This happens, for example, at sites where at most one or two circle
remain (Centre Line indeterminable) or where the recumbent stone has fallen or been removed
(Perpendicular Line indeterminable).
The primary orientations display a highly significant general trend: whether we consider the Centre Line or the Perpendicular Line, the azimuths from the site interior towards the recumbent stone all fall, without a single exception, within an azimuth band about 90 ° in width centred upon SSW. in
itself
roughest out
Even
this is a trend which can only be explained if astronomical observations (albeit of the kind,
undertaken
the sites.
merely in order to determine absolute directions) were used in setting
The geographical area they span is far too large for sightings upon any particular
terrestrial feature to have been any use.
4.3.4
~E~g~
~
~
~2 ~
2~o~t~i~
- It is clearly of interest to plot horizon dis-
tances against azimuths relative to the Centre or Perpendicular Line orientation. Fig. 11 shows the results
for the Perpendicular Line.
There is a complete avoidance of nearby (category A) horizons
in the general direction of the primary axis; the boycott extends over a total of 37 ° . (In the case
Megallthlc Astronomy
of the Centre Line this is only about 11°.)
271
These figures imply that when viewed along the Perpen-
dicular Line from, say, 10m behind the recumbent stone, there is never any nearby horizon above the recumbent
stone.
There
does not, however, appear to be any preference for a particularly distant
(as opposed to merely non-local) horizon.
The
fact that nearby horizons are shunned completely over the recumbent stone may provide evidence
of an interest in celestial observations near to the horizon which should not be obscured by nearby land
or
vegetation.
approximate beneath
In the great majority of cases the flankers cut the horizon as viewed from
eye-height
the
horizon.
in the interior of the ring, whereas the recumbent stone between them lies Thus the inner edges of the flankers appear to "partition off" a stretch of
horizon which the recumbent stone lies beneath; and it is not unlikely that this stretch of horizon might have been used for some sort of astronomical observation. The azimuth range over which nearby horizons are shunned is much wider in the case of the Perpendicular Line than the Centre Line, providing some evidence that it is the direction perpendicular to the recumbent stone, rather than the Centre
Axis, that was of particular astronomical significance; however this conclusion merits much
fuller discussion.
These
results
observations (1980)
on
authors. a
provide affected
the
basis
a the of
strong layout fifty
motivation for examining whether any more specific astronomical of
the
sites. This possibility has been investigated by Burl
indicated
azimuths deduced from the existing surveys of earlier
His conclusions about the astronomical significance of the RSCs are now in question, and
detailed consideration of the indicated declinations on the basis of the new data is in progress
(Ruggles & Burl 1985).
It does however appear that a lunar, rather than a solar, significance will
be demonstrable.
s.1 l s ~ t ~ i g s
If
the preceding three sections have talked a great deal about precision of alignments and statis-
tical
rigour,
them,
then this merely reflects the overriding flavour of the megalithic astronomy debate, even in
recent years. omical
and
very
little about the nature of the sites themselves and the people who built
The ultimate quest remains, for many investigators, to examine the nature of astron-
observations
made
in prehistoric times: other archaeolHical
evidence merely serves as an
arbiter in the astronomical debate, or else to provide background evidence.
From
the point of view of the great majority of archaeol~ists
questionable. the
Why
construction,
this whole approach has always been
concentrate upon astrOnomy when so many other factors might also have motivated design and use of sites about which we know so little?
The answer is of course
272
C.L.N. Ruggles
that
this
is
the
approach o f the astronomer or the h i s t o r i a n
reflection
of
the
backgrounds
approach ations
is
inevitably
of
the
majority
o f sciences and t h a t i t
o f workers i n t h i s t o p i c .
is a clear
The a r c h a e o l o g i s t ' s
more b r o a d - b a s e d , and in recent year s a number o f a r c h a e o l o g i c a l i n v e s t i g -
have been undertaken in which astronomy i s c o n s i d e r e d as merely one o f a number of p o s s i b l e
factors
influencing
Lation
from
s i t e placement and o r i e n t a t i o n .
those
considerations
described
were
so
far.
These s t u d i e s have proceeded l a r g e l y i n i s o -
They have s t a r t e d t o uncover evidence t h a t a s t r o n o m i c a l
a f a c t o r i n f l u e n c i n g the s i t i n g
monument at d i f f e r e n t
times i n B r i t i s h
prehistory,
and design o f a v a r i e t y o f d i f f e r e n t
types o f
and have s t a r t e d t o g i v e us some clues about the
r o l e played by astronomy in the Lives o f the people concerned.
A
number
o f a r c h a e o l o g i s t s have s t u d i e d the o r i e n t a t i o n s
f r e q u e n t l y been observed. a
of burial
tombs and common p a t t e r n s have
A w i d e l y - q u o t e d example i s the e a r t h e n long barrows o f Cranbourne Chase,
g r e a t many o f which are a l i g n e d NW/SE w i t h the Larger end at the SE (Ashbee 1970: 162-163).
other
i s the Clyde c a i r n s o f Scotland where a n o r t h - e a s t e r l y
c o u r t o f the long a x i s of the c a i r n (Henshall 1972: 9 9 ) . tation
orientation
An-
i s f a v o u r e d f o r the f o r e -
Henshall has a l s o commented on the o r i e n -
of the c a i r n s o f n o r t h e r n Scotland: she notes t h a t o n l y 12 o f the 114 c a i r n s i n her Orkney-
Cromarty group face the western h a l f o f the compass, the normal o r i e n t a t i o n (Henshall 1963: 104) and t h a t an e a s t e r l y d i r e c t i o n universally,
by
orientation
of
the
builders
the
of
being between NE and SE
a l s o seems t o have been p r e f e r r e d , al t hough not
Maes Howe type c a i r n s (1963: 130).
Clava c a i r n s o f I n v e r n e s s - s h i r e .
Burl
(1981b) notes the SSW
A recent p r o j e c t on the chambered c a i r n s o f
Orkney i s d e s c r i b e d below.
5.2 ! ~
~!~b-~e~
evidence the
~!iEO~
relating
Land
on
architectural
~
which
they
lived.
form,
their
relationship
e v i d e n c e ) , and t h e i r
There
are
two
henges
stone) pottery other
best known.
not
His main source o f data i s the Orkney chambered c a i r n s : t h e i r t o o t h e r m a t e r i a l evidence ( o t h e r monuments, a r t e f a c t s
and
relationships.
in
other
words
found at d i f f e r e n t styles, objects
cairns places
Other monuments o f the same age i n Orkney i n c l u d e f o u r s e t t l e m e n t s i t e s ,
and a number o f i n d i v i d u a l
s i t e s as w e l l ) , bered
spatial
and second m i l l e n n i a bc and
at l e a s t 76 chambered c a i r n s known in Orkney, o f which Maes Howe ( S e c t i o n 2.2 above) i s
the
present:
Fraser (1983) has attempted t o draw t o g e t h e r many l i n e s o f
t o the people who i n h a b i t e d Orkney d u r i n g the t h i r d
burial
perhaps
~O~X-
Unstan
assemblages
standing stones. of
s i t e s seem t o f a l l Ware
and
There are two d i f f e r e n t
small p o r t a b l e a r t e f a c t s
(objects of pottery,
were
Grooved Ware.
However Fraser concludes t h a t the a r t e f a c t s and
o b j e c t s (such as r i t u a l
they t u r n up at s e t t l e m e n t
i s t r u e both f o r Unstan and Grooved Ware s i t e s .
places where the o r d i n a r y a c t i v i t i e s
where a c t i v i t i e s
of special significance,
objects) took place.
bone and
i n t o one o f two g r o u p s , c h a r a c t e r i s e d by two d i s t i n c t
found in chambered c a i r n s are not p e c u l i a r t o them ( i . e . and t h a t t h i s
material cultures
of daily
life
He i n f e r s t h a t cham-
were c a r r i e d o u t : they were
r e q u i r i n g the manufacture and use o f s p e c i a l
Megalithic Astronomy
A
locational
analysis was undertaken in an attempt to explore the relationships between the cham-
bered cairns and the landscape of Orkney. geology,
273
Various aspects of the landscape were identified, namely
soils, land use capability, topography, vegetation, altitude, visibility from a location,
drainage, ease of approach to a location and the nature of the nearest coast. The distribution pattern of the chambered cairns was examined in relation to each of these aspects in turn, and then to all
the
nium,
factors taken together. Since the chambered cairns cover a time period of about a millen-
such an analysis can only hope to reveal factors influencing the siting of cairns which span
this period. The assumption is inherent that the qualities of the landscape assumed in the analysis were relatively unchanging during the period under consideration.
Some o f the r e s u l t s o f the u n i v a r i a t e approach were as f o l l o w s . (i)
The
accessibility
w i t h no s u p e r f i c i a l (ii)
The
of
b u i l d i n g stone may have c o n s t r a i n e d the c a i r n - b u i l d e r s
t o p r e f e r Land
d e p o s i t s (such as a mantle o f peat ) over land w i t h such d e p o s i t s .
chambered c a i r n s seem p r e f e r e n t i a l l y
and f r e e l y d r a i n e d , i . e .
t o be l o c a t e d near t o s o i l s which were easy t o work
on or near the farming land o f the b u i l d e r s .
(iii) They were located in a variety of topographic positions (i.e. valley bottoms, coastal plains, hill slopes, hill tops, etc.). (iv) The distribution of present-day vegetation does not appear to be correlated with the distribution of chambered cairns. (v) The cairns were not located in places with extensive sectors of restricted visibility. (vi) They were generally located in positions which are easy to approach. (vii) They
show a pronounced tendency to be located close to the coast: high cliffs were preferred
over major beach systems as the nearest coastal type.
To some e x t e n t i t from
the
is misleading to isolate different
others.
actually
importance. A p r i n c i p a l
land . second
appears
typically
extensive
a c t i n g t o g e t h e r or vyi ng a g a i n s t one a n o t h e r i n
components a n a l y s i s ( F r a s e r 1983: S e c t i o n 12.3) r e v e a l s two d i s t i n c t
l o c a t i o n . The f i r s t
It
c o n s i d e r i n g each o f them i n i s o l a t i o n
The a c t u a l d e c i s i o n about where t o p l a c e a chambered c a i r n would, presumably,
have r e s u l t e d from any number o f f a c t o r s ,
of original
factors,
to
fit
typically
consists of a hillslope
l o c a t i o n i n marginal a g r i c u l t u r a l
best those c a i r n s which are small and round w i t h simple chambers. The
c o n s i s t s o f a l o c a t i o n on land now reckoned t o be good f o r a g r i c u l t u r e ,
views
models
o f the land w i t h i n 5 km.
I t appears t o f i t
and w i t h
best t hose c a i r n s o f o t h e r s s i z e s and
shapes.
FinaLly,
interpretation tation visibility
(1983:
Fraser
of
as
cairns of
ch. 15) examines v a r i o u s r e l a t i o n s h i p s
symbolic.
and a r t e f a c t s most r e a d i l y open t o
One o f these i s symbolism connected w i t h the sky, such as the o r i e n -
with respect t o the s u r r o u n d i n g Land and the v i s i b l e
cairns,
the
demarcation
sky; o t h e r s are the i n t e r -
o f space w i t h i n and around c a i r n s , animal and b i r d bones
found w i t h i n c a i r n s , and d e c o r a t i o n s (such as s p i r a l s )
found on s c u l p t e d s t o n e s .
274
C.L.N. Ruggles
Conclusions from s t u d i e s o f the c a i r n o r i e n t a t i o n s were as f o l l o w s . (i)
Those c a i r n s which are e l o n g a t e d seem p r e f e r e n t i a l l y
(ii)
Amongst
t o be o r i e n t e d i n the N~P-SE q u a d r a n t s .
those c a i r n s w i t h e l o n g a t e d chambers, t h e r e i s no p a t t e r n o f o r i e n t a t i o n
amongst the
chambers. (iii)
As
a
group,
the
known
chambered
c a i r n s o f Orkney have passages which are p r e f e r e n t i a l l y
o r i e n t e d outwards from the chamber t o the south and e a s t .
To determine the o r i e n t a t i o n position
near
material
if
divided
into
restricted
to the
of visibility,
the e n t r a n c e passage o f the c a i r n , e i t h e r on the ground s u r f a c e o r on the mound view
was r e s t r i c t e d
sectors of visibility
the h o r i z o n t a l view.
Oistant:
the h o r i z o n was scanned w i t h a p r i s m a t i c compass from a
visibility
by the c a i r n i t s e l f .
The classes o f v i s i b i l i t y
Restricted:
l e s s than 500mr.
The data were s i m p l i f i e d
by q u a n t i z i n g each azimuth c i r c l e
Fraser
(Oavidson
evidence
tall
v e g e t a t i o n as i t
The
results
of
is
& Jones 1984) t h a t the environment at the time was as d e v o i d o f
apparent around 0 ° . visibility,
The p a t t e r n i s more pronounced than those f o r e i t h e r
s u g g e s t i n g t h a t the d i s t a n t v i s i b i l i t y
was the i m p o r t a n t f a c t o r .
observed i s s i g n i f i c a n t l y
The
as
particular bility are
now,
points
of
One
inter-
in cert ain direct ions,
Applying a Kolmogorov-Smirnov t e s t ,
azimuth d i s t r i b u t i o n
question
The observed azimuth d i s t r i b u t i o n
i s b i m o d a l , w i t h a major peak around 140° and a minor one around 270° .
or r e s t r i c t e d
anything,
In c o n s i d e r i n g v i s i b i l i t y
is today.
visibility
trough
mediate
i n t o 10° b i n s .
f o r the 76 known c a i r n s are sunvmarised i n F i g . 12.
distant
major
were:
exceeding 5 km. between 500m and 5 km.
notes
f o r each c a i r n was
depending upon the d i s t a n c e t o t h e n e a r e s t p i e c e o f land which
Intermediate: visibility visibility
The azimuth c i r c l e
if
Fraser concludes t h a t the
n o n - u n i f o r m at the 1% l e v e l .
w i t h the Recumbent Stone C i r c l e data above, i s what i s s p e c i a l about t hese the compass t h a t r e q u i r e s d i s t a n t v i s i b i l i t y .
o f l o c a l topography i n f l u e n c i n g o r i e n t a t i o n w i d e l y d i s p e r s e d o v e r 20 i s l a n d s .
c i s e l y w i t h measurements o f t h i s
of visibility
As w i t h the RSCs, the p o s s i -
can be d i s c o u n t e d si nce the c a i r n s
Although a s t r o n o m i c a l design can not be t i e d down v e r y p r e -
accuracy, i t
is interesting
t o note t h a t at t h e l a t i t u d e
o f Orkney
when the c a i r n s were e r e c t e d , midwinter s u n r i s e oc cur r ed at an azimuth o f around 140° . Azimuth 270° i s o f course t h a t o f the e q u i n o c t i a l
A
relationship
one other
cairn
s e t t i n g sun.
o f dominance and subservience might be expressed i n r e l a t i o n
being in a dominant l o c a t i o n i n r e l a t i o n
cairns
then i t
to others.
t o chambered c a i r n s by
I f one c a i r n can be seen from many
i s always p r e s e n t and can never be ignored by the users o f the o t h e r c a i r n s .
I f messages were passed between c a i r n s by v i s u a l means, then a h i g h l y i n t e r v i s i b l e important
link
in the d i s s e m i n a t i o n o f i n f o r m a t i o n .
c a i r n becomes an
However F r a s e r ' s a n a l y s i s of i n t e r v i s i b i l i t y
FIG. 12.
I-
N
¢-
e-
"0
00 0 o Q~
~iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiil~
0
10
l
20
I
!
40
!
60
|
50
Number o f c a i r n s w i t h d i s t a n t ,
Number of cairns
30
I
76
i n t e r m e d i a t e and r e s t r i c t e d
70
I
iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii
~ii{iiiiii{iiiii!!iiiiii{iiiiiiii{iii!!{{{iiiilil.. .%.
iiiii iiiiiiiiiiii:iiiiiiiii iiiii!! iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii
,iiiiiiiiiiiiiiiiiiiiiiiii!iiii!!!iiiii!!i!iiiii!iiiiiiiiiii!iiiiiiiiii~, .....
,iiiiiiiiiiiiiiiiiiiiii!iiiiiiiiiiii!iigii!iiiiiilgHi~i~e ...........
iiiiiHiiiiiiiiiiiiiiiiiii!iiiii!iiiiiiiiiiiiiiiiiL
ii?iiiiiiiiiiiii!iiiiiiiiiiiiiiiiii!!iiiiilP
Orientation of visibility f o r 76 chambered c a i r n s i n Orkney. visibility by 10 ° s e c t o r i n azimuth. A f t e r Fraser (1983).
000
270-
180-
090-
000
o=
o
~°
276
C.L.N. Ruggles
found
no
strong
evidence
for
the
existence of power relationships expressed in terms of cairn
location.
Fraser
concludes
places
which
that that the neolithic inhabitants of Orkney situated their chambered cairns in
were
chosen
so as to make certain solar observations possible.
These observations
could
have
been of importance to a farming people in signalling significant times in the agricul-
tural
year.
He also suggests that the chambered cairn, situated in the physical centre and social
heart
of
the
community,
would
have been the obvious meeting place to rejoice and celebrate the
changing o f the seasons.
Fraser's in
work
approach
has d e l i b e r a t e l y
been d e s c r i b e d at some l e n g t h .
between an a r c h a e o l o g i s t concerned o n l y i n passing w i t h a s t r o n o m i c a l symbolism and an
astronomer or e n g i n e e r p a r t i c u l a r l y
Some recent
analyses
of
grave
seeking evidence o f a s t r o n o m i c a l achievement.
orientations
considered i n the r e s t o f t h i s a r t i c l e considered isolation,
bear
some similarity
the
from
cemeteries d a t i n g much l a t e r than the p e r i o d
are worthy o f mention h e r e , because the t e c h n i q u e s and ideas
to
those
and some r a t h e r elementary p i t f a l l s
Studies o f the o r i e n t a t i o n s yoking
I t g i v e s a f e e l f o r the d i f f e r e n c e
discussed above, y e t they have proceeded i n apparent might have been avoided had t h i s not been the case.
o f Saxon graves have been undertaken by Rahtz (1978).
the a n t h r o p o l o g i c a l l i t e r a t u r e
- particularly
a classic article
He begins by i n =
by Rose (1922) - t o suggest
kinds o f reason why i t might be d e s i r a b l e f o r a head or body t o be Laid i n the e a r t h i n a p a r -
ticular
direction.
The
most g e n e r a l l y held b e l i e f ,
ground
in a c e r t a i n d i r e c t i o n
to
so f o r e v e r ; or t h a t u l t i m a t e l y
do
rise,
and
the
direction
because i t
of
(i)
~29~,
seems, i s t h a t the body i s placed i n the
p o i n t s t o something, or looks at something, and c o n t i n u e s
at some dramatic end t o the w o r l d the corpse or s p i r i t
rising will
T y p i c a l reasons f o r o r i e n t a t i o n ,
it
be determined i n some way by the d i r e c t i o n
will
o f the body.
as quoted by v a r i o u s a u t h o r s , were summartsed by Rahtz as f o l l o w s .
depending on age, r a n k , s o c i a l s t a t u s , sex, morals ( s t a t e o f g u i l t
or innocence at
d e a t h ) , manner o f death ( d i s e a s e , v i o l e n c e or i n bed) . (ii) ~ ! ~
2£
~2~X
2~E~!,
which either the spirit is due to travel to, or the corpse will
spend eternity gazing towards. (iii)
A[ea
2~
females
2EJgiO~= being
X!~
oriented
£~2~C~ towards
~£ 2 ~ £ ~ E ~ ! ~ , the
west,
such as h u n t i n g or farming grounds; o r
t o the s u n s e t , when the w i f e w i l l
p r e p a r e her
husband's meal. ( i v ) Sett~emeo~ individual (v) ~ 2 £ ! ~
o£
~29~
~J~-
Graves may p o i n t i n the g e n e r a l d i r e c t i o n
graves may p o i n t t o the dead p e r s o n ' s house. 2~ ~ 2 D ~ D ~ -
such as c r o s s e s , h i l l - f i g u r e s
or idols.
of the sunset, or
Megalithic Astronomy
(vi) ~9~Z ~ j ~ J O 9 ~ (vii) 5 ~ L
9£ ~ U ~ J -
~ L
2~L
277
including shrines and former burial places.
Z2~;
so that the cemetery may impress, or at least be seen, by those
passing by. (viii) Natura~ ~eat~es such as mountains, clefts, hills, rivers, contours and rocks. (ix) O~he~
9 ~
~
~ -
The orientation of one grave may determine that of others that
follow. (x) As~£onom~£a~ observations of celestial bodies at their rising, traverse or setting.
In addition we should bear the following thoughts in mind. (xi) Individual some
of
perversities
may
come into play, such as amongst the Ashanti
(Ucko 1969: 273),
whom deliberately bury their dead in the opposite direction to that considered the
norm, in the belief that the dead turn themselves round after a certain passage of time. (xii) Many other controlling factors might have prevailed, of which we can have no knowledge. (xiii) The gravedigger might have made an arbitrary decision based on some passing whim.
The
orientation
of particular graves will be the result of many factors, of which some might have
been
identified here.
set.
He showed that all but 2% of the 305 measurable bodies lay with their feet oriented on points
within the
the
local
alignment
east-facing
Rahtz concerned himself with the large Saxon cemetery at Cannington, Somer-
solar arc. He concluded that the position of sunrise could well have determined
of the corpse, thereby criticising the assumption that the observed predominance of
graves
pagan
practice.
quent
orientation
necessarily represented the graves of Christians; it could be the remnant of a
Furthermore if the position of sunrise at the time of death determined the subseof the corpse, then one could make observations about the seasonal incidence of
mortality.
The
distribution
data
represent
orientation ence
of
is
of a
the Cannington graves is shown in Fig. 13(a).
unimodal
Although it is clear that the
distribution, centred around azimuth 110 ° , Rahtz concludes that solar
a major factor, and refers to arguments that the distribution might indicate evid-
seasonal death, with a high proportion of deaths occurring in summer, when bubonic plague
hits hardest.
In
a discussion of a Saxon cemetery at Finglesham, Kent, Hawkes (1976) established a similar range
of
east-west orientation, shown in Fig. 13(b).
distributed
The Finglesham orientations are clearly unimodaIly
more or less about due east, yet again the hypothesis of solar orientation was consid-
ered.
Fortunately
Brown
strongly
favours
mortality
model.
(1983) a
normal He
has
recently
distribution
compares
the
pointed about
expected
out that the statistical evidence in both cases a preferred orientation rather than the sunrisedistribution
of orientations given random deaths
t o mid j u l y
7 0 °.
6 0 ~_
50 t
FIG. 13.
outside solar arc
I
I
a
20 I
I
30 I
1
I I I
I
40
feet orientation
I
I
I
5 I
I
10
I
I
b
I
I
20 I
I
30 I
I
I I
I
40
feet orientation
I
I 10%
0
Grave o r i e n t a t i o n w i t h i n the soLar arc at Cannington, Somerset (A) and at Finglesham, Kent (B), together with the expected d i s t r i b u t i o n given a sunrise o r i e n t a t i o n model and random incidence of deaths throughout the year (C). A f t e r Rahtz (1977), Hawkes (1976) and Brown (1983).
1403
/
e a r l i e r a p r i l o r e a r l y s e p t 8 0 ~_ e a r l y a p r i l or m i d s e p t . l a t e r m a r c h or l a t e r s e p t 9 0 _~ mid m a r c h or l a t e s e p t . e a r l i e r m a r c h o r e a r l y o c t 100"e a r l y m a r c h or e a r l i e r o c t l a t e f e b or l a t e o c t 1 1 0 ~mid f e b or l a t e o c t - n o v . e a r l y f e b or e a r l y n o v 1 2 0 ~. l a t e r j a n or mid n o v dec to earlier jan ___130:
l a t e r april or e a r l i e r a u g mid april or later aug
e a r l y m a y or l a t e j u l y - a u g
mid m a y or l a t e r j u l y
latemay
outside solar arc
40 ~
Azimuth
~
10 0
I
5
0
I
No. of g r a v e s i n s i d e s o l a r a r c : 2 0 0
No.of graves inside solar arc : 299
¢n
Megalithic Astronomy
throughout the
279
the year, which is of course sinusoidal (Fig. 13(c)), with a mortality model based upon
seasonal incidence of plague deaths during the fourteenth century.
tality at a certain season might explain the maximum concentrations, the
abnormally
low
death
rate
around the solstices.
While a model of high mor-
it does not adequately explain
The simple, preferred-orientation model,
explains the data far better.
An
independent
statistical
study of grave orientations, this time collating data from five Roman
and post-Roman cemeteries including Cannington, has also appeared recently (Kendall 1982). Although the
data
from
all five sites are distinctly unimodal in character, the sunrise-seasonal model is
considered against concentration models about single and multiple orientations, and mixtures of the two.
There are a number of dubious astronomical statements such as
..the
sun
does
not
travel
through twelve distinct monthly periods within its annual arc.
There are, in fact, seven periods of which five are two-monthly.. and
there
almost and
is
a
diagram
vertically,
points
out
implying,
quite erroneously, that the sun rises much more steeply, and
around the equinoxes.
that
However Kendall eventually dismisses the seasonal model
the observed distributions about a mean orientation may be explained by the
error between the direction being aimed at and that achieved by the grave-digger.
That
d i s c u s s i o n s such as t h a t on Saxon grave o r i e n t a t i o n s
statistical
reappraisal, while sophisticated statistical
c a r r i e d out with c o m p a r a t i v e l y l i t t l e munication with one
possible
statistical
noting quite rightly
factor; rigour,
is indicative
can be
o f the yawning com-
Many a r c h a e o l o g i s t s view archaeoastronomy
t h a t the a n a l y s i s o f o r i e n t a t i o n s
meanwhile many archaeoastronomers p e r s i s t but paying l i t t l e
f o r so Long w i t h o u t adequate
t e s t s upon m e g a l i t h i c o r i e n t a t i o n s
archaeological reappraisal,
gap which has p e r s i s t e d i n t h i s touchy a r e a .
suspicion,
can p e r s i s t
i n v o l v e s astronomy as o n l y
in analysing t heir
data w i t h g r e a t
a t t e n t i o n t o f a c t o r s o t h e r than a s t r o n o m i c a l c o n s i d e r a t i o n s
which might have i n f l u e n c e d s t r u c t u r e o r i e n t a t i o n s .
5.4 ~gO~ c i r c l e s
Recent
work
studying without to
a
two
a r c h a e o l o g i s t s ( B a r n a t t & P i e r p o i n t 1983) has broken important new ground by
group o f s i t e s
f o r evidence o f a s t r o n o m i c a l o b s e r v a t i o n s usi ng h o r i z o n f o r e s i g h t s ,
but
s t r u c t u r e s on the ground being o r i e n t e d upon the f o r e s i g h t s i n q u e s t i o n . T h e i r approach i s
detect
vable
by
in
those areas on t h e ground from which c e r t a i n a s t r o n o m i c a l events would have been o b s e r particular
h o r i z o n n o t c h e s , and t o see whether the placement o f s i t e s w i t h i n t h a t g i v e n
area f a v o u r s Locations where a good many such events would have been v i s i b l e .
Recalling have
been
isolation
Fraser's
work d e s c r i b e d above, we see t h a t a s t r o n o m i c a l i n f l u e n c e s o f t h i s n a t u r e might
o n l y one o f many f a c t o r s i n f l u e n c i n g s i t e placement, and t o c o n s i d e r any one o f them i n might
be m i s l e a d i n g .
B a r n a t t and P i e r p o i n t do, however, a l s o c o n s i d e r one o t h e r f a c t o r
280
C.L.N. Ruggles
which
might have influenced site placement: the desire for prominent siting, which is very similar
to Fraser's intervisibility criterion.
Barnatt and Pierpoint concentrate on stone circles, suggesting that they were the focal points of a society
that
happened
to have an interest in astronomy (amongst, presumably, many other things).
Machrie Moor on Arran was chosen for a case study.
The area has a large concentration of monuments
including six stone circles of various designs, three chambered tombs and over twenty round houses, together with associated clearance cairns and field walls. and
a
single
about the
standing
stone.
There are also two large cairns, a cist
All these sites are positioned on a relatively well-drained ridge
1 km 2 in extent surrounded by deep peat bogs.
Because of the large number of stone circles,
moor provided an ideal opportunity to consider the precise location of its monuments and their
astronomical potential.
In
order
tions
to compare the actual siting of the Macrie Moor stone circles with other potential loca-
within
the Moor, the whole area was covered with a conceptual grid, its intersections being
at 100m intervals.
Measurements were then taken from the site locations themselves, and from every
grid
intersection.
were
assessed
In order to estimate visual prominence, the relative amounts of visible land
from
each point by recording the general area of land visible, potential zones for
settlement and the presence of field monuments and other archaeological evidence. Many similarities with Fraser's approach are evident. The authors conclude that the stone circles on Macrie Moor were placed at optimally prominent locations,
in strong contrast to the other types of site on the moor,
although some riders have been pointed out in an accompanying comment (Ruggles 1983b).
The
eastern
and western skylines were classified as having eight well-defined features and twenty
others, which although clearly visible with the naked eye, are not very obvious targets. 23
features
excluded. were
to the north and south fell well beyond the horizon range of the sun or moon and were ALL
measured
enormous,
A further
and
28
features studied were regarded as potential foresights and their declinations
by theodolite from each grid intersection. one
wonders
whether
an
The amount of work involved was clearly
adequate picture might be gained elsewhere from computer
studies using large-scale Ordnance Survey maps which are now stored digitally.
Astronomical a
map
was
particular circles these
events considered s i g n i f i c a n t
and
p l o t t e d showing areas from which p a r t i c u l a r s o l a r or Lunar events could be observed in notches.
The
superimposed. areas
were the soLar s o l s t i c e s and the Lunar s t a n d s t i l l s ,
only
results
are
shown in Fig. 14, w i t h the a c t u a l l o c a t i o n s o f the stone
Five out of seven c i r c l e s occupy the areas w it h two o r more l i n e s , although
make up some 27% of the t o t a l . rather
than
a
stone c i r c l e .
The only r e a l l y b a d ly-p la ce d s i t e i s probably a
complex
ring-cairn
B a r n a t t and P i e r p o i n t conclude t h a t t h e r e is a
distinct
bias in the s i t i n g of stone c i r c l e s f o r Locations f a v o r a b l e t o astronomical o r i e n t a t i o n .
Megalithic Astronomy
!
: .
~
0 n u m b e r of 1 horizon 2 orientations 3 4
.
.
281
.
• circles A standing stone
0
2 0' 0
FIG. 14. The astronomical potential of the Macrie Moor area, Arran. Shading shows how many solar solstitial or lunar standstill risings or settings can be viewed behind prominent horizon features from a given spot. The location of stone circles within the area is plotted. After Barnatt & Pierpoint (1983).
5.5 ~ b ~ g ~ ! ~ g ~ !
An
attempt
points
e~JD~
has
about
been
made by the present author (Ruggles 1981c; 1982b) to examine methodological
studying
orientations.
There are three general classes of factor which might have
influenced structure orientations: (i) Astronomical towards
considerations.
the
horizon
Structures
might
be aligned upon the heavenly bodies, e.g.
rising or setting points of the sun at a solstice or other significant
time in the year. (ii) Azimuthal
directions.
Structures
might
be deliberately or preferentially aligned north-
south, or in some other direction. (iii) Features type,
on
the
natural
whence
ground.
Structure orientations might be towards nearby sites of a certain
features such as distant mountains, or directions of local significance (e.g.
ancestors
came); or else they might depend upon the local lie of the land (e.g. tomb
entrances downhill).
Any
given
factors, been the
orientation acting
will,
together
presumably,
actually
have
resulted
or vying against one another in importance.
from any number of d i f f e r e n t For example, i t might have
desired to s i t u a t e a ceremonial s i t e in a p o s i t i o n with wide views, within the r e s t r i c t i o n of builders'
available
t e r r i t o r y and avoiding prime a g r i c u l t u r a l Land; a desired solar or lunar
282
C.L.N. Ruggles
rising the
or
setting
other
never
alignment behind a d i s t a n t mountain, f o r example, might have been secondary t o
r e q u i r e m e n t s , and a compromise reached.
prove t h a t any p a r t i c u l a r
eration:
it
might
In the absence o f independent e v i d e n c e , we can
structure orientation
was m o t i v a t e d by a s i n g l e o v e r r i d i n g c o n s i d -
have a r i s e n through the chance combination o f o t h e r f a c t o r s ,
i n a c c e s s i b l e t o us.
many o f which are
Even sheer human p e r v e r s i t y might have p r e v a i l e d , as i s known from the Ashanti
case mentioned above.
Thus we are o f n e c e s s i t y f o r c e d t o seek a l a r g e data sample and t o hope t h a t
the causal f a c t o r being t e s t e d w i l l
lead t o t r e n d s d i s t i n g u i s h a b l e
at high s i g n i f i c a n c e
l e v e l s from
the e f f e c t s o f o t h e r causal f a c t o r s .
In p r a c t i c e one t e s t s any p a r t i c u l a r tations
that
being
tested.
would
check of
other
causal
factors
~2~
think of testing;
long
barrows
merely lead t o random background noi se amongst the data
face s o u t h - e a s t e r l y d i r e c t i o n s ,
type
(ii)
hypothesis, explains
c o n c l u s i o n s can r e s u l t .
and
possibly
the o r i e n t a t i o n
under
a
type ( i )
t r e n d q u i t e simply:
be.
of
any
particular
significant.
Our f i r s t
causal
trends
in
the d a t a .
be i d e n t i f i e d tures
are
will
cases
achieving
(i)
and ( i i )
significant
individually.
directions
all
simplification
h y p o t h e s i s need t o
d e f i n e what c o n s t i t u t e s a
candidates at each s i t e .
in
field
t o consi der s i g n i f i c a n t ,
p r o c e d u r e , by d e f i n i n g s i g n i f i c a n t
At each s i t e ,
the observed d i s t r i b u t i o n
directions
in
any range o f h o r i z o n " i n d i c a t e d " by a When data are accumulated
o f i n d i c a t e d d e c l i n a t i o n s or azimuths can be com-
pared
statistically
w i t h the expected d i s t r i b u t i o n
icant
accumulation
o f d e c l i n a t i o n s around a p a r t i c u l a r
object or objects.
overwhelm any genuine
under any p a r t i c u l a r
can be d e f i n e d in terms o f azimuth or d e c l i n a t i o n .
from a number o f s i t e s ,
celestial
inevitably
For example, i n o r d e r t o t e s t the h y p o t h e s i s t h a t s t r u c -
terms o f d e c l i n a t i o n and azimuth r e s p e c t i v e l y . structure orientation
t h a t they w i l l
we can surmount the problem o f how many d i r e c t i o n s
considerable
This causal f a c t o r
I f too many, then so many f o r -
a l i g n e d upon d i s t a n t mountains, we must f i r s t
d i s t a n t mountain, and then i d e n t i f y
In
24).
p r o c e d u r a l problem, t h e n , i s t o decide how g r e a t t h i s number should
In case ( i i i )
preferentially
However a t y p e ( i i i )
h y p o t h e s i s must depend upon a number of d i r e c t i o n s being
be c o n s i d e r e d s i g n i f i c a n t
f o r each s i t e
under a
l i e on p r e d o m i n a n t l y NW-SE r i d g e s .
I f too few, then t r e n d s o f p o s s i b l e importance may be missed.
tuitous orientations
Three q u a r t e r s o f
i s t h a t the b u i l d e r s were compelled t o
the mounds along the r i d g e s upon which they were e r e c t e d ( i b i d . :
testing
deemed
h y p o t h e s i s as w e l l . it
If this
As an example, consi der the group
a f a c t which would undoubtedly show up as s i g n i f i c a n t
does not produce random azimuths because the s i t e s a l l
The
must be examined.
on Cranborne Chase examined by Ashbee (1970: 2 3 - 2 4 ) .
them
out
t h e n , t o check (as f a r as i s p o s -
however any r e a s o n a b l e p o s s i b i l i t i e s
i s not made, demonstrably i n v a l i d
hypothesis
It is essential,
t h a t the o r i e n -
There may, o f course, be many p o s s i b l e causal f a c t o r s not now apparent t o us, which
never
earthen
lay
h y p o t h e s i s a g a i n s t the a l t e r n a t i v e
in q u e s t i o n were randomly d i s t r i b u t e d .
sible)
we
orientation
g i v e n random s t r u c t u r e o r i e n t a t i o n s .
A signif-
v a l u e , say, can be r e l a t e d t o a p a r t i c u l a r
Megalithic Astronomy
It
283
is advisable to analyse both indicated azimuths and declinations, since the former are directly
related
to particular celestial objects, whereas the latter are more useful in considering whether
ground-based ones.
hypotheses
could
in
fact
explain any observed trends just as well as astronomical
However in view of the considerable additional work involved, no type (iii) hypotheses have
been considered methodically in any detail by any authors.
Debates
such
as
possibilities tions
that at Ballochroy can never be satisfactorily resolved on their own merits; new
can
always it seems be dreamed up by one side in the argument to counter any objec-
raised by the other, and there is insufficient evidence to assess on statistical grounds the
hypothesis
that
Stonehenge
the
ensures
that
tunity
to
any
astronomically alignments were in fact deliberate.
problems are different but equally confounding:
the profusion of interrelated data
no statistical analysis will produce meaningful results.
test
At complex sites such as
There is rarely any oppor-
an astronomical hypothesis by archaeological means, and the experience at Kintraw
shows that even this can be inconclusive and lead to interminable debate.
Burl
(1981b)
present trend
at is
author
has
pointed out some poignant examples where convincing astronomical alignments are
individual sites, but when these sites are seen as part of an archaeological group the not
repeated
and the alignment then appears to have come about by chance.
The present
was disillusioned about the solstitial interpretation of Ballochroy when he first visited a
similar three-stone row at Duachy, which was not solstitially oriented. Patrick (1979) has objected to
Thom's
lunar interpretation of the Kilmartin, Argyll site on the basis that an architecturally
similar site at Barbreck has no lunar alignments (in fact he was wrong about Barbreck - see Ruggles 1984a
but
the line of argument is one which needs to be pursued rather more often than usually
happens).
The message is clear: studies of groups of sites seem by far the best way forward.
The
of a lunar significance
idea
Mull
and
ideas
of
mainland Burl
Argyll,
(1980;
in the o r i e n t a t i o n s o f c e r t a i n f r e e - s t a n d i n g m e g a l i t h i c s i t e s i n
particularly
1981b;
and ceremonial s i t e s .
higher-precision
summer s o l s t i c e .
involved
the
extreme
trends)
of
were for
(as opposed t o the more t e n -
r e q u i r e no more than the o b s e r v a t i o n o f the f u l l
Burl's earlier positions
lunar, orientations
However the l unar o r i e n t a t i o n s
t h e r e is c o n v i n c i n g evidence amongst the western S c o t t i s h s i t e s
tative the
lends c o n s i d e r a b l e support t o the
1983) t h a t a s t r o n o m i c a l , and p a r t i c u l a r l y
i n c o r p o r a t e d in c e r t a i n m e g a l i t h i c b u r i a l which
the stone a l i g n m e n t s ,
moon n e a r e s t t o
interpretation
o f the Aberdeenshire Recumbent Stone C i r c l e s
the moon in i t s
1 8 . 6 - y e a r cycl e and thus would have r e q u i r e d
284
C.L.N. Ruggles
organised work
Lunar
(Ruggles
observations &
Burl
over
1985)
a period of at l e a s t twenty years; however the r e s u l t s of new
seem t o modify t h i s conclusion in the d i r e c t i o n o f lower p r e c i s i o n
o b s e r v a t i o n s , in Line w i t h the conclusion f o r the western S c o t t i s h s i t e s .
That
the moon, r a t h e r than the sun, seems predominantly t o have i n f l u e n c e d the o r i e n t a t i o n o f c e r -
tain
free-standing
the
megalithic
ethnographic r e c o r d .
d a i l y one; i t such
as
s u r p r i s e in view o f what i s found in
The cycle Of lunar phases is the most obvious cycle in the sky a f t e r the
demarcates time periods of a convenient l e n g t h ; and i t
the
seasonal
s i t e s cOmes perhaps as l i t t l e
human menstrual
calendars
cycle.
c l o s e l y matches n a t u r a l cycles
Knowledge o f the Lunar month is almost u n i v e r s a l , and many
are lunar-based ( B a i t y 1973; Thorpe 1981; Carlson & yon del Chamberlain 1985).
On the o t h e r hand horizon s o l a r o b s e r v a t i o n s , apart from in a few well-known cases such as the Hopi (McCluskey 1977), tend t o be of secondary s i g n i f i c a n c e
( f o r a poignant example see Turton & Ruggles
1978).
Even
if
we accept the marginal evidence from the western S c o t t i s h s i t e s in favour of o r i e n t a t i o n s
upon
the
southern major s t a n d s t i l l ,
o f the f u l l
It
t h i s could have been e a s i l y achieved: occasional o b s e r v a t i o n s
moon nearest the summer s o l s t i c e would have s u f f i c e d .
is i n t e r e s t i n g t h a t the western S c o t t i s h s i t e s manifest marginal evidence f o r o r i e n t a t i o n s upon
the w i n t e r s o l s t i c e but not f o r any o t h e r s o l a r events. cases
of
winter
solstitial
Howe discussed
alignments in m e g a l i t h i c tombs - such as those at Newgrange and Maes
in Section 2 above - no evidence has emerged b e f o re t h a t the w i n t e r s o l s t i c e might
have been of p a r t i c u l a r nographic
While t h e re are some well-known i n d i v i d u a l
record,
ceremonial i n t e r e s t .
In f a c t , t h i s a lso comes as no s u r p r i s e from the e t h -
where w i n t e r s o l s t i c e ceremonies are o f t e n o f great importance, the sun needing
t o be turned back from i t s
southward movement (Thorpe 1981; Carlson & yon deL Chamberlain 1985).
6.3 Z~2 Q ~ g Q ~ b ~
Throughout
the
decades
of debate about m e g a l i t h i c astronomy, e s p e c i a l l y as regards s i n g l e s i t e s ,
the emphasis has been upon the p o s s i b i l i t y whose
primary
course
of
effort
has
motivation
great been
was
interest spent
t h a t many were p r e h i s t o r i c o b s e r v a t o r i e s : t h a t i s ,
as centres f o r o b s e r v a t i o n s of the sun, moon or s t a r s .
sites
This is o f
t o the h i s t o r i a n o f science: as a r e s u l t a very g r e a t deal of time and
investigating
the
reality
of p a r t i c u l a r
astronomical a lig n m e n t s, t h e i r
intended p r e c i s i o n , and so on.
However like
who
evidence wide
the are for
archaeologist, particularly it.
Looking
on in h o r r o r , sees a group o f astronomers, engineers and the
fascinated
by astronomical and engineering achievement, and seek out
The dangers in doing t h i s are t w o f o l d .
Firstly,
range of o t h e r evidence bearing upon the purpose o f a s i t e ,
we may miss or m i s i n t e r p r e t a
and upon the people who b u i l t
it.
Megalithic Astronomy
Secondly, remains
we may unwittingly project our own ideas of "achievement" onto the people whose material we
pologist, facets
285
are
studying.
This "ethnocentrism" is a tendency which the archaeologist or anthro-
in his more general experience studying different cultures and his wider interest in all
of
the societies and their material culture - not just astronomical observations - is in a
far better position to recognise.
The
real problem is to separate statistical discussion concerning the intentionality and precision
of certain alignments from the subsequent consideration and interpretation of such results in their archaeological context.
However attention is constantly being diverted from this essential problem
by debates on largely irrelevant points. "science precision
v.
ceremonial"debate.
as
ammunition
in
this
The most distracting of all is undoubtedly the persistent
Many investigators insist on using data about intentionality and debate: evidence in favour high-precision observations becomes
evidence in favour of "scientific" astronomy; refutation of high-precision indications and evidence in
favour of low-precision ones becomes evidence in favour of "ceremonial" astronomy.
Strongly on
the side of "scientific" astronomy is, for example, MacKie (1981; MacKie et a~. 1984); in the other camp In
are authors such as Butt (1980; 1981b; 1983), Barnatt and Pierpoint (1983) and Fraser (1984). fairness, all these authors derive support for their view from independent archaeological evid-
ence.
Thus MacKie (1977a; 1977b) believes that a "two-tier" social system was in operation in some
megalith-building societies, the top tier being a elite of astronomer-priests undertaking intricate astronomical
observations. Burl, on the other hand, sites the funerary association of much ancient
astronomy in support of the idea that it was a ritual, not a scientific, practice.
In
fact,
the rigid dichotomy between science and ceremonial is undoubtedly misleading; we need to
consider first the existence and precision of intentional orientations, astronomical and otherwise, and
then to interpret them using far more than two crude (and actually very vaguely-defined)
gories.
As
Renfrew
cate-
(1981) has pointed out, to insist on such a rigid and ultimately subjective
dichotomy between science and non-science serves only to obscure the nature of what surely ranks as an interesting development in the evolution of scientific thought.
What
we
are really asking from the dispositional evidence a ~ £ ~ 2 ~ astronomy is (i) how important
an influence were astronomical considerations upon the placing (and possibly the design) of a site; and (ii) what was the precision of any astronomical observations made. basis
When this is decided on the
of the statistical evidence, then and only then is the time to consider this evidence in its
social context alongside the other strands of archaeological evidence at our disposal.
Megalithic
astronomy
aeoastronomy.
has now become merely one (albeit important)
topic in the new field of arch-
Alongside archaeoastronomy has developed ethnoastronomy.
During the last five years
286
C.L.N. Ruggles
the
two
fields
seem
to have become firmly established as disciplines in their own right, and to
have acquired a considerable momentum. astronomy: the A~chaeoas~onom~ its
supplement to the ~ouzna~ ~o~ ~he H~sto£~ o~ Astronomy, which began
separate existence in 1979, and the bulletin of the Center for Archaeoastronomy at the Univer-
sity
of
Maryland,
archaeoastronomy in
There are now two publications entirely devoted to archaeo-
which started up shortly afterwards. In September 1979 the first international
symposium was held in Oxford, England, and the second is planned for January 1986
Merida, Mexico.
The first international conference on ethnoastronomy was held in Washington DC
in September 1981.
Attempts
to
define the disciplines, or even to tie down their fields of interest and define their
bounds, have tended to come in retrospect and to be rather vague. ences
of
exist
some
which
are far less remote in time, and for which strands of evidence are available other than just
the
approach between, say, British archaeoastronomers
Certainly there are huge differ-
4000
present
ethno-
and
years
interested in cultures which ceased to
ago and American archaeoastronomers,
disposition
of
archaeoastronomy
archaeological as
remains.
interested in pre-Columbian cultures
In general terms one might simply describe
the study of astronomical practice amongst contemporary and past
societies.
Ethno- and archaeoastronomy arose through the p a r t i c u l a r science, the
and
disciplines
ultimately in
many
of their
form
merely
be j u s t i f i e d
isolation
practicioners
in r e l a t i o n
and
continue t o have a background i n these f i e l d s .
one aspect o f the study o f human s o c i e t i e s
from o t h e r f a c t o r s ,
archaeoastronomy
i n t e r e s t s o f astronomers and h i s t o r i a n s o f
t o such s t u d i e s .
However
in g e n e r a l , and can o n l y
The dangers o f s t u d y i n g a s t r o n o m i c a l p r a c t i c e
or as an end in i t s e l f ,
have a l r e a d y been mentioned. Thus whether
ethnoastronomy should r e a l l y be t r e a t e d as d i s c i p l i n e s
i n t h e i r own r i g h t
is
the s u b j e c t o f much debate at the moment.
There
are,
in f a c t ,
v a t i o n s . The f i r s t tice
two i m p o r t a n t ways o f j u s t i f y i n g
interest
i s the e x t e n t t o which we can hope t o r e c o n s t r u c t r i t u a l
in one form or a n o t h e r seems t o perform a v i t a l
ficult,
a particular
role in all
societies,
in astronomical obserpractice.
Ritual prac-
but i s n o t o r i o u s l y d i f -
some would say i m p o s s i b l e , t o r e c o n s t r u c t from the e t h n o g r a p h i c (and p a r t i c u l a r l y
the a r c h -
a e o l o g i c a l ) r e c o r d . Edmund Leach i s one of a number o f s o c i a l a n t h r o p o l o g i s t s who have attempted t o recognise
s o m e g e n e r a l f e a t u r e s about r i t u a l
practice.
He demonstrated (Leach 1961: 124-36) t h a t
the boundaries between w e l l - d e f i n e d time p e r i o d s tend t o be marked o f f by r i t u a l seasonal f e s t i v a l s .
Astronomical o b s e r v a t i o n s p r o v i d e a r e l i a b l e
activities
such as
way o f demarcating these time i n t -
e r v a l s ; the cycles o f the sun, moon, p l a n e t s and s t a r s are by f a r the most dependable r e g u l a r l y curring natural events.
Thus a s t r o n o m i c a l o b s e r v a t i o n s are r e l e v a n t , o f t e n c r u c i a l ,
the t i m i n g o f f e s t i v a l s ,
and hence a s t r o n o m i c a l symbolism tends t o f e a t u r e i n the r i t u a l
themselves.
By
studying astronomical practice in Living societ ies,
a n c i e n t s i t e s where r i t u a l
re-
in determining activities
or a s t r o n o m i c a l symbolism i n
p r a c t i c e s may have o c c u r r e d , may g i v e us some important i n s i g h t s .
Megalithic Astronomy
The
second
recent the
justification concerns even wider issues.
years
past,
human
concerns
and
that
behaviour".
latter
side
287
A vigorous debate amongst archaeologists in
the extent to which archaeology should merely be attempting to reconstruct to
which it should be trying to interpret its evidence in terms of "laws of
Are
we
trying simply to describe history, or perhaps to explain it?
On the
of the fence, there might be some hope in studying practices which are almost univer-
sal, in the hope of correlating their development with the complexity of the society concerned.
The
movements
universal some
the
concern,
hope
example,
of has
systematic
even
(i.e. (see,
However
the most primitive of hunter-gatherer societies.
astronomical practice with other facets of society.
that of
with
increasing the
heavens)
increasing
complexity
of
This gives us
Leach (1954), for
ways of thinking about time (hence more
is correlated with the emergence of a priestly class of
social stratification).
An such view may of course be over-
e.g., Thorpe 1981) and can only be developed with the aid of ethnographic field-
sufficient
1978).
moon and stars are, to judge by the ethnographic evidence, of almost
amongst
correlating
observations
simplistic of
sun,
suggested
time-keepers
work
of
methodological
rigour (for an attempt in this direction see Turton & Ruggles
in the light of such correlations ethno- and archaeoastronomy acquire a valuable
role
in extrapolating from astronomical evidence to facets of the society in question which may be
less
directly
observable.
This remark has particular force in archaeological applications, where
facets of great interest may leave no direct trace in the archaeological record.
Archaeoastronomical
evidence
nonetheless
suffers, in common with archaeological evidence in gen-
eral, from the limitations of the archaeological record. variety and
of
even
Ruggles
1978:
the
590),
featuring
activities have
lithic
practices, such as the recognition and naming of stars and constellations,
the use of heliacal risings and settings to determine seasonal activities (e.g. Turton &
symbolism
we
widespread
It is clear from ethnographic work that a
tend in
to
leave no trace in the archaeological record.
ritual activities may be incorporated in the design of centres where such
were performed, and hence may well be recoverable. extensive
sites
wrong
of
remains of burial and (presumably) British prehistory.
motives)
However astronomical
these
are
the
Our best hope of success lies where
ritual sites, as in the free-standing mega-
Indeed, this brings us full circle, for (albeit perhaps for sites
upon
which attention has been concentrated since the
earliest emergence of the subject (e.g. Lockyer 1909).
Prehistoric astronomy is both an area of importance and one in which the surface record can give us valuable information in advance of excavation. investigations
(for
example an excavation strategy)
than merely to collect data. aeology
as
hypotheses ation,
and
In archaeology as a whole, it is possible to design in order to test particular hypotheses rather
This becomes increasingly important for the overall progress of arch-
resources become increasingly scarce.
If we can use the surface data to set up viable
in areas of importance, then we have both a working hypothesis in advance of any excavalso
a strategy which should save resources if ever we are in a position to undertake
288
one.
C.L.N. Ruggles
If
corroborative
evidence on prehistoric astronomy is sought from excavation, then survey
work can isolate groups of sites where excavation might preferentially be undertaken, together with hypotheses (solar and lunar association) which might be tested. The stone rows of Mull and mainland Argyll,
and
their
possible
lunar association, are in the author's view a particularly exciting
example which has cropped up in recent years.
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!~ ~
~9
~E~
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