In other cases, however, evidence of horizon observations might be more readily identifiable in the archaeological record of the future. The Zuni, for example, had sun-watching stations used for horizon observations prior to the summer solstice. And the inhabitants of the Polynesian island of MANGAREVA established observation places for noting the summer and winter solstices against suitable landmarks, such as adjacent islets or mountain ridges, often erecting stones upon them as foresights. This example bears some similarity to the interpretation of many of the British megaliths, erected in the third and second mil-lennia B.C.E., put forward in the mid-twentieth century by the Scottish engineer, Alexander Thom (see THOM, ALEXANDER). Basing his conclusions upon surveys of many hundreds of STONE CIRCLES, SHORT STONE ROWS, and single standing stones, Thom concluded that “megalithic man” had undertaken high-precision observations of the sun and moon using distant mountainous horizons as the observing instrument. The megaliths, according to Thom, marked where to stand and, in many cases, pointed out the horizon foresight (such as a conspicuous notch between two mountains) that was to be viewed.
Thom’s results did not stand the test of time. One reason is that his data set included a wide variety of sites spanning a wide geographical area and a period of some two millennia (see MEGALITHIC MONUMENTS OF BRITAIN AND IRELAND). Subsequent analyses that have been restricted to certain areas during particular periods, and have taken account of a wider range of archaeological evidence, have been more successful. The Scottish RECUMBENT STONE CIRCLES (RSCs) are particularly enlightening in this respect. These are a group of several dozen stone circles confined to an area within about fifty kilometers (thirty miles) of Aberdeen in northeastern Scotland. Their distinguishing feature is a single recumbent stone flanked by two tall uprights, which are without exception oriented between west-southwest and south-southeast, that is, within a quarter of the available horizon. Furthermore, they are consistently aligned upon the midsummer full moon, suggesting that ceremonials were carried out there when the midsummer full moon was passing low over the recumbent stone. This is a conclusion backed up at one excavated site, Berrybrae, where scatters of quartz and burned flint—white stones whose color is similar to the light of the moon—were found in the vicinity of the recumbent stone. However, more recent excavations at other sites have confounded the issue.
The RSCs were modest monuments, apparently serving relatively small farming communities around 2000 B.C.E. Aligning them upon the moon at an important time, and also if possible upon a conspicuous feature in the landscape such as a prominent hill (as is the case at many but not all of the circles), tied them into nature in two different ways. This almost certainly served to reinforce the sacred status of the monuments for the people they served. It seems likely that society in this area at the time never became centrally organized and controlled, and this has bequeathed to us a set of small, similar monuments among which we can easily spot repeated patterns. This enables us to catch a glimpse of some aspects of ritual tradition and worldview—a glimpse that points strongly to the moon as a principal focus of attention. Similar conclusions have been reached in investigations of SHORT STONE ROWS in southwest Ireland.
A step on from identifying and interpreting monumental alignments is to ask why the monuments were placed where they were and not elsewhere. Answering this question involves a detailed investigation of whole landscapes to identify potential alternative locations. Such an investigation was carried out in the late 1980s in the northern part of the Isle of Mull, off the west coast of Scotland. It showed that a set of five stone rows found there, apart from being consistently aligned upon the moon, were all placed so that Ben More—the most conspicuous mountain on the horizon in the area—was on the very margin of visibility, clearly in sight to one side of each row but completely hidden by intervening ground from the other. One suggestion is that the stone rows’ main significance was as some sort of symbolic boundary marker between areas from which this (sacred?) mountain was, and was not, visible.
One supposition that emerges from these studies of monuments incorporating astronomical alignments is that many of them became “special” when the astronomical body in question appeared at the appointed place. At these times, their sacred power was surely reinforced. Another way in which a similar effect could be achieved—creating a very considerable visual impact at certain special times—was through the interplay of sunlight and shadow. Widespread evidence indicates an interest in creating carefully orchestrated interplays of shadow and light at sacred places, sometimes producing special effects visible on only very rare occasions. A famous example occurs at the passage tomb of NEWGRANGE in Ireland. Here, for a few precious minutes after sunrise on a few days around winter solstice, the dark interior of the tomb becomes lit up by sunlight shining directly down the passage. Even in the present day, such hierophanies can capture the imagination and become the focus of great public spectacles, whether or not they were actually intended by the builders. A case in point involves the pyramid of KUKULCAN (El Castillo) at Chichen Itza. It contains a staircase on each of its four sides, and at the base of the northern staircase is the carved head of a serpent. On days close to the equinoxes, the light of the late afternoon sun falling across the stepped corner of the pyramid creates the effect of a serpent’s body, which only “appears” at these times. This spectacle now attracts tens of thousands of visitors. In contrast to Kukulcan, no serious doubts exist that the Newgrange hierophany was actually intentional; though, by its nature, it could never have formed a great public spectacle, since the space inside the tomb was confined. This dramatic effect was intended for the ancestors, or for ancestral spirits.
What was the purpose and meaning of such hierophanies? There is no simple answer, but further clues can be found by looking at more modest examples, often to be found in rock art. By carefully placing rock art designs, sunlight could be made to play across them at certain times, with impressive effect. A number of interesting examples are to be found in California, which was densely populated by hunter-gatherer groups prior to the European conquest. The Luiseсo, for example, had an intense ceremonialism, a rich sky lore, and a calendar regulated by various astronomical observations. Although their seasonal calendar was lunar-based, they observed and celebrated the solstices, attaching particular importance to the winter solstice, which they regarded as a time of cosmological crisis. Solar imagery is evident at various Luiseсo rock art sites, and light-and-shadow effects have been discovered at three or four of them, more than one involving daggers of sunlight that bisect painted discs.