Irish Passage Tombs & Megalithic Art at Knowth

From Minds or Moons? by Laurie Darcus


Knowth Kerbstone 84In a bend of the Boyne River in Co. Meath Ireland, megalithic passage tombs dating back some 5000 years hold some of the mysteries of life, and death, as experienced by Neolithic people who built them. The Knowth, Dowth and Newgrange sites of Brugh na Bóinne (Boyne Valley) are referred to in Irish Mythology as sacred places, and once excavated it was revealed that many of the large stones used in construction of the cemeteries were decorated with engravings.

In this paper I explore how this art, particularly at Knowth, has been interpreted based on the current available literature. I begin with a general introduction of the Neolithic and passage graves to provide some context for the interpretations of the art. The interpretations are divided into four main themes: decorative; altered states of consciousness; astronomic/calendric; and miscellaneous. I argue that the art is not simply decorative and the symbols may have originated during altered states of consciousness with meaning related to astronomy and calendars.

The Neolithic in Ireland

The Neolithic period, beginning approximately 5000 B.P., saw the development of agriculture in Ireland. These first farmers of Brugh na Bóinne cleared the land of the forests of oak, elm, hazel, birch, and alder, in order to expose the most fertile soil in Ireland, allowing access to some of the best areas for farming of cereals and grazing for domesticated animals (Eogan 1984: 1; Eogan 1986: 11; O'Kelly 1989: 36).

Stone tool artifacts show that Neolithic people had progressed to using blade technology and pressure flaking to produce arrowheads, javelin heads, knives, and scrapers, and tool kits included polished stone axes hafted to wooden handles. Pottery too was made and used during this period (O'Kelly 1989:39-40, 45).

According to Brennan (1983:40), the Neolithic farmers of the Brugh na Bóinne lived a fairly complex way of life. The surpluses of the rich agricultural base provided the people with options to pursue other interests, such as time to create and exchange goods and services, and time to organize large groups for the construction of megalithic passage tomb monuments.

Passage Tomb of Ireland

There are remains of approximately 300 passage tombs in Ireland, built on hilltops or high elevations (O'Kelly 1989: 97; Eogan 1986: 24). Though not the only types of tombs in Ireland from the Neolithic, passage tombs are unique in that many of them include engraved ornamentation on some of the structural and surrounding stones (O'Kelly 1989: 97, 106).

Passage tombs are normally grouped into cemeteries and the best known are those at Brugh na Bóinne. The three main mounds are Newgrange, Knowth and Dowth, and all are surrounded by smaller satellite tombs. The sites cover an area just over 4 kilometers long and 3 kilometers wide (O'Kelly 1989: 97, 100; Eogan 1984: 201).

The main Knowth mound holds two tombs and is surrounded by seventeen smaller passage tombs, some simple in plan, others more complex. Construction of tombs was methodical in nature and the main mounds may have taken over 30 seasons to construct O'Kelly citied by Aranyosi, 1999: 365).

At the end of the parallel sided passageway the inside chambers are simple square or circular openings or form a cruciform shape. The chambers were covered with a well engineered corbelled roof built with lintels laid across orthostats (O'Kelly 1989: 104; Aranyosi 1999: 364).

The roof stones were placed circularly one above the other, each successive layer projecting closer to the centre, until the stones met at the top (Stewart 2001: 348). Layers of sod, boulder, clay, shale and stones were laid over the passage and inside chamber, and the entire mound was bordered by large kerbstones (Eogan 1984: 5-6, Eogan 1986: 24). Some of the larger stones, exceeding four tons, likely came from up to five kilometers away (Eogan 1986: 114, Aranyosi 1999: 364).

Herity (1974: 37) considers these tombs to be architecturally elaborate. He points out that the longer the passage, nearer the centre the inside chamber would be placed. There the greatest pressure from the highest point on the mound would bear down on the inner chamber, and yet after 5000 years these structures have not collapsed.

Channels were cut into the upper surfaces to drain off water seeping into the mounds keeping the interior dry (Stewart 2001: 348). The tombs "are probably the greatest architectural achievements of Neolithic man in Europe" (Stewart 2001: 347).

Eogan writes, "the corbelled roof had achieved almost a true arch", and these Neolithic architects had an "awareness of effects of stress and ways of counteracting it must have been acquired" and their "rock selection shows a grasp of geology and the structures demonstrate architectural and engineering abilities so these must have been a thinking and conscious people" (1986: 217).

Brennan (1983), Eogan (1986), Herity (1974) and O'Kelly (1989) agree that to build these structures would have taken much man power. The incredible investment of labour and effort required to build these monuments "violates Zipf's (1949) principle of least effort" and is wasteful in the Darwinian model, where the ideal is to expend the least amount of energy to produce offspring and sustenance, and energy is not wasted on other unnecessary activities.

The building of monuments might have been a means of display of power by high ranking individuals with the ability to conscript labour, and by proving this political power they attracted others to align with them (Aranyosi 1999: 357). Brugh na Bóinne was capable of supporting the sizeable community required to provide the labour for such an endeavor and O'Kelly states, Only a society with great material and intellectual reserves could have envisaged the monuments in the first place, and perhaps spiritual reserves were needed as well. These large edifices are surely the concrete embodiment of a belief in the hereafter, in the necessity of providing a House for the Dead so that some spirits least would live on to perpetuate the memory of the builders and of the community as an entity (1989:124).

Eogan agrees that a sound economic basis was necessary to sustain and feed a large number of people during the erection of these structures and considers the resulting passage tombs to be important religious centres for a rich and prolific society (1984: 322, 1986: 15). Nowakowski describes the construction sites as centres of a ceremonial landscape, and to enhance their importance they were set apart from the locations of day-to-day activities yet made visible day-to-day by their elevated locations (1997: 40).

From an ancestral worship point of view, these monuments may mark out and reinforce claims to ancestral lands, while providing a place for veneration of the ancestors (Whitley 2002: 121). In an agricultural community, ancestors were particularly important because current generations were indebted to previous generations for their labour which established and continued the mode of subsistence (Whitely, 2002: 121). The tombs, visible in silhouette from many vantage points in the area, served as a reminder of the "link between the living, the ancestors and the land, a relationship that that lay at the core of Neolithic belief systems" (Nowakowski 1997: 40; O'Kelly 1989: 100).

The mounds of Newgrange, Knowth, and Dowth appear in the earliest Irish literature. The area was considered the domain of the Tuatha De Danaan, the earliest known native Irish gods who had descended from the skies to inhabit Ireland, disguising themselves as a supernatural race of wizards and magicians (Brennan 1983: 10; Whitley 2002: 123, Nowakowski 1997: 46).

The mounds are first referred to as a burial site for the Kings of Tara in 12th century AD literature (Brennan 1983:14, Eogan 1986: 186). "The hosts of great Meath are buried/in the middle of the lordly Brugh" according to 13th century AD Book of Ballymote (Eogan 1986: 186). Excavations began at Knowth in July 1941 by Professor R.A.S. Macalister and it was revealed that at Knowth, and other passage tombs, cremation was the burial rite.

Grave goods were not in abundance, and only a few articles were found including pottery, bone and antler pins, stone pendants, and chalk marbles, many decorated (O'Kelly 1989: 105, Eogan 1984: xiii). There were single, multiple, and successive burials (Eogan 1984: xiii, 1, O'Kelly 1989: 105).

Bones found were both cremated and un-cremated, though in undisturbed sites, only cremated bones have been recovered. Found in some tombs were the bones of single individuals, but more frequently the evidence points to more than one individual deposited collectively (children, young persons, and adults) (Eogan 1984: 20, 175).

Evidence from excavations shows that the number of individuals buried in tombs was relatively small, and this may mean that the monument itself fulfilled whatever the requirement was and burials were of a token nature (O'Kelly 1989: 124). Because burials likely did not include all individuals, the minority that were buried may have been representational, "a foci for ritual and ceremony" (Eogan 1986:178). Part of that ceremony at Knowth may have been a procession around the decorated kerb stones of the great mound, and perhaps each decorated stone became a station within a system (ibid.).

Eogan suggests that burials might have taken place at a particular time of year and the ritual was a communal affair, focusing on ancestor worship to encourage ancestors with power and influence to bring good fortune to the community (1986:178, 181). Based on the discovery that the passage ways at Knowth, one facing east the other west, are filled with light as the sun rises and sets on the days of the equinoxes, illuminating the decorated stones at the end of the passage ways, it could be that there were two such rituals annually at Knowth, one at the vernal equinox (beginning of the growing season, an important time for agriculturalists), and one at the autumnal equinox (fall harvest time, another key time for farmers) (Eogan 1986:178, Brennan 1983: 56).

Researchers and witnesses have observed illumination of passage ways at multiple tombs. At Newgrange the sun's rays pass through a roof box at sunrise on the day of the winter solstice fully lighting the passage and making the decorated backstone observable to anyone inside the tomb (Stewart 2001: 348, Brennan 1983: 7). There are other passage tombs where passage illumination occurs at marked times of the solar year, such as equinoxes and solstices, suggesting the Neolithic people of Ireland had been observing and recording solar movement and cycles.

The Decorated Stones: Neolithic Art

Knowth Kerbstone 5County Meath, home to the mounds of the Brugh na Bóinne, holds more decorated megalithic surfaces than found in the rest of Atlantic Europe, and half of that, Europe's greatest concentration of megalithic art, is found at Knowth (Kinnes 1988: 345, Eogan 1986: 146).

In total 250 stones at Knowth have been found to be formally decorated, including external kerbstones, internal orthostats, sills, capstones, and corbels (Eogan 1986: 148). Of the 134 kerbstones at Knowth, more than half are engraved with major compositions, while many others have incidental markings (Brennan 1983: 102). Art work is not confined to large sophisticated passage tombs such as Knowth. It can also be found on simpler passage tombs (Cleal 1999: 135).

Engraving Techniques:

The major techniques used to decorate the stones at Knowth and other passage graves were picking or pecking with a chisel or punch stone tool, and incising along the surface of the stone using a sharp edge of probably flint or obsidian (Cleal 1999: 135, Eogan 1986: 148).

There can be various grades of depth of decoration on the same stone and the engraving techniques produced a three dimensional effect, the image standing out in false relief. Picking was used to create an outline and to fill in designs. Pick dressing removed the thin outer layer of the stone, eliminating irregularities and exposing a new surface with an improved colour.

Smoothing of the pick marks was accomplished by hammering (Brennan 1983: 128). Designs appear on stones on one side or both sides (including hidden sides facing the inside of the tomb), and in some cases are below ground, signifying application of decoration prior to placement but contemporary with the construction of the tombs (Cleal 1999: 135, Eogan 1984: 183-186).

Interpretations of the Art

I have broken the interpretation of the tomb art into four main themes: miscellaneous interpretations; decorative; altered states of consciousness; and astronomic/calendric.

The decorative and miscellaneous categories have little supporting evidence, but I will briefly cover those to provide a full examination of the range of interpretations of passage tomb art.

Miscellaneous Interpretations: Geometric in concept and non-representational is how O'Kelly describes the Knowth motifs. He does believe that the motifs were probably symbolic, religious, or magical in context, but he concludes, "it is unlikely that we will ever discover what any of them meant since we cannot know the minds or the emotions of a people who did not know how to write and who are separated from us by more than 4000 years" (1989: 111).

Despite the truth to that last statement, many have tried to uncover the truths behind the designs. Decoration on Neolithic grooved ware has been traced back to passage tomb art as a source. The designs on the grooved ware may have served to differentiate social groups through association with specific designs, or alternately, served to promote integration of social groups during rituals through esoteric meanings of the designs (Cleal 1999).

Designs have also been linked to religion in a general way. The wealth in sufficient food allowed Neolithic people to look beyond the pursuit of daily survival to questions of religion and the cult of the dead with funerary rituals (O'Kelly 1982: 122). Application of the art was a permanent visual confirmation of part of the Irish Neolithic ideology (Eogan 1986:146, 169). Herity (1974) proposes that the motifs on the stones are anthropomorphic in design, for example the spirals would represent eyes. He suggests that these anthropomorphic impressions are representations of gods and goddesses associated with places of burial (1974: 106). Nowakowski attributes the Neolithic symbols to a sun-worship religion (1997: 45). O'Kelly proposes that the act of engraving was the important ritual, not the designs themselves (1982: 148).

Decorative only: Brennan lists those who had reduced their analysis of the symbols to mere decoration: Macalister (1921); Breuil (1934), Piggot (1954), Ó Ríordáin and Daniel (1964); and Lynch (1967) (Brennan 1983: 35). Decorations were merely an enhancement to architecture.

Altered States of Consciousness: During rituals, including Shamanistic rituals, individuals will enter altered states of consciousness through various means (e.g. constant drumming or singing; long periods of deprivation of food, water, light; blood loss; consumption of hallucinatory plants , etc.). Bourguignon (1968) sampled 488 societies ranging from foragers to complex societies, and found that 437 had some form of institutionalized altered states of consciousness (Lewis-Williams 1993: 55).

Lewis-Williams and Dowson (1993), and Eichmeier and Hoffer (1974) (cited in Lewis-Williams 1993: 55) have established a neuropsychological model where during altered states of consciousness, geometric entopic phenomena (often referred to as phosphenes), intrinsic to the human nervous system, are "seen" by those in the altered states. The theory has been successfully tested both under laboratory conditions and in ethnographic situations, and the stage I entopic component of the neuropsychological model seems universal.

The geometric shapes that are produced during the first stage of altered states of consciousness match those found in Neolithic art. The meanings of the shapes would have been formed culturally and now difficult for us to determine. The function, however, might be explained as a form of political power. Where altered states are common in the rituals of a society, a set of elite may seize control of the "special" experiences as a means of expressing their society's ideology and justifying their elevated status. This status would allow further control of resources and labour (Lewis-Williams 1993: 56, 57, 59, Lewis-Williams 1990: 407-408).

A contrary view on phosphenes comes from Hodgson (2000) who argues that the there is an underlying neurophysiological causative factor in the recognition of simple lines and phosphene type forms. The primary cortex plays a central role in the processing of visual information and would be connected with the making of geometric shapes in early human art, even without Shamanistic type ritual.

Altered states of consciousness is taken further by Dronfield (1996) who proposes that the tunnels of the passage tombs, and the concentric circles and spiral motifs found in megalithic art, are indicative of the ‘tunnel experience' of altered states. The tunnel provides a means for accessing supernatural worlds, and the realm of the dead – allowing communication between the living and ancestors who have passed on.

Calendric/Astronomical: Conwell (1864), and Coffey (1892), recognized and wrote about the solar emblems they recognized at Knowth (Brennan 1983: 35). Brennan states, "the problem posed by highly abstract visual concepts is that, although narrow in intention, they are broad in extension,…Only the context can reveal which meaning is intended" (1983: 37).

With a background in art research, Brennan (1983) began systematic field research in 1979, using direct empirical observation at the mounds to test his theory that the symbols on the stones had astronomical significance based on the alignment of the mounds to equinoxes and solstices previously mentioned. Brennan's analysis is based on his assumption that the rich agricultural lifestyle with its surpluses would have afforded Neolithic people time for other pursuits such as astronomy and time keeping (1983: 40).

He and a colleague experienced both lunar and solar illumination of passages, and also discovered that shadows from standing stones outside the passage ways would be closest to the vertical lines engraved on the entrance stones at Newgrange and Knowth at the equinox sunset. In 1980 they were able to discern and work out diurnal sundials at Knowth (Brennan 1983; 31). At Site 1, Kerb 7 of Knowth, it has been observed that the sun's shadow passes from one ray to the next at approximate 1.5 hour intervals on a rayed motif with 16 rays (Eogan 1986: 170). Counting using the marks at the end of the rays on Kerbstone 15, 1.5 hours X 16 = 24 hours.

Within the motifs, Brennan saw direct representations of the moon (circles, crescents), the sun (circles with rays). Both he asserts are unmistakable universal symbols that transcend the barrier of language (1980: 1). The Calendar stone, located in the southwest section of Knowth, bears a series of symbols that return in a cycle. The outer cycle of symbols has been interpreted as recording the phases of the moon daily through the month while the inner circle plots each lunar month in relationship to the solar year over a period of five years, and the device located in the lower right corner works with the inner cycle to tabulate 19 solar years, after which phases of the moon repeat on the same calendar dates as the first cycle (Brennan 1980: 97).

Stooke (1994) interpreted the arcs as representational of the lunar maria, which extends west, north and east of the lunar central highlands and which is visible to the naked eye. Unlike Brennan who interpreted the crescents on kerbstone 52 as phases of the moon, Stooke identifies these arcs as reflecting the orientation of the lunar maria as it crosses the sky during one night (1994: 44).

The spirals at Knowth, but specifically the spiral on kerbstone 52 with its six turns plus a seventh half turn, he explains, are depictions of the lunar orbit where "the elevation of the full moon at the meridian seems to rise for six or seven months, then fall for six or seven months" (1994: 45). Another common motif is a pair or set of arcs facing each other, which he interpreted "as images of the maria on the rising and setting full moon" (Stooke 1994: 48). Stooke believes these are the oldest depictions of lunar markings thus discovered, and "at Knowth we have a detailed record of astronomical observations, particularly of the lunar maria and motions, which possibly incorporates a representation of a lunar calendar" (1994: 39, 52).

Referring to Newgrange, Stewart declares, "the sophisticated Neolithic people of about 3,000 B.C. produced as accurate a solar calendar as their near contemporaries of Egypt" (2001: 348). Brennan also claims to recognize evidence of a calendar or counting marks in sets of triangles, and in zigzags/serpentines – each rise and fall a count (1983: 132). Calendars have been developed based on the positions and the rhythm of the movements of the sun, moon, and perhaps stars as well (Brennan 1980: 82).

These Neolithic engravers had created what Brennan refers to as "visual computers", calculating the movements of celestial bodies and measuring time and space (1980: 70). A Neolithic calendar would have regulated, or at least marked, activities throughout the year such as planting, harvesting, and moving of domestic animals (Brennan 1983: 40-41). Early in the twentieth century the use of an eight part calendar in megalithic orientations was explained by astronomer, Sir Norman Lockyear (Brennan 1983: 53).

Critical Analysis

Reviewing the four themes above, the miscellaneous themes (social group identification and/or integration, religious) were vague and held little specific evidence. Religion is such a broad category, so although I agree that these designs could form part of a religious or ritual purpose, none of the authors fully explained exactly what specific concepts such a religion or ritual would encompass.

I do agree though that the site held a special purpose, such as ritual use, as it was situated high on a hill, away from the daily activities. As far as these motifs serving a purely decorative function, Eogan says it best when he explains that much time, trouble, and skill was involved in the creation of this art, clearly indicating its importance (1986: 147).

Most art at least has meaning for the artist. In the case of the art at Knowth, many of the geometric designs were repeated, often in similar groupings, which would suggest some meaning and preplanning of the art. It has been discussed above that these sites likely served a ritualistic purpose. Ritual often involves altered states of consciousness, and perhaps the engraved motifs were inspired by stage one altered states of consciousness.

The difficulty with this explanation is that the motifs would have taken long time periods to produce through pecking techniques, and the altered state of consciousness surely would have worn off prior to the completion of even a portion of the engraving. Alternatively, incising could have been a means to immediately create the entopic image, and later the image was embellished to present a more obvious decoration. Lewis-Williams and Dowson present a convincing argument for the source of the geometric designs from individuals in states of altered consciousness based on laboratory and ethnographic studies.

If Hodgson is correct, that the visual cortex is the source of phosphenes, it makes even more sense that the art at Knowth is derived from the human neurological system. Doodle marks made by people while talking on the telephone, or listening to lectures, resemble the circles, dots, spirals, triangles, wavy lines and grid marks that we witness in Neolithic art.

They do seem to come from the subconscious. If the art at Knowth was inspired by a neuropsychological model, it is likely that meaning was applied to the art post-creation by the society carving and viewing the earliest resultant designs. That meaning has not been addressed by these authors other than to state it could be associated with ritual. Looking through the archaeological and earliest written records around the globe, there seems to be a fascination with the sky. Egyptians, Mayans, Greeks, and Romans all left indications of astronomical study. If this is a natural curiosity of humans, finding astronomical meaning in the engravings at Knowth would seem reasonable.

Without television, the non-static night sky would have offered an interesting display. Evidence for orientations of the passages of these tombs allowing full illumination during sunrises and sunsets at equinoxes and solstices (and possibly lunar illumination as well), provides support for the astronomic interpretation of the symbols at Knowth and other Irish passage tombs. Brennan and Stooke provide compelling arguments for lunar observation in their interpretation of the art. From astronomy the natural progression is to tie the movements of the heavenly bodies to a calendar, or time keeping.


The passage tombs of Brugh na Bóinne are steeped in myth and reverence going back a very long time. With a lack of archaeological evidence for permanent habitation sites, it probably was a place used for rituals incorporating the dead.

From their architectural capabilities we know that these were reflective and reasoning people. The art, which may have formed in the minds of Neolithic people through entopic images, either as natural images neurologically inherent or brought on by altered states of consciousness, must have taken on some meaning for the people of that time.

There are good arguments presented for astronomic and calendric symbolism, and perhaps those heavenly bodies represented the supernatural world, the realm of the dead, but all interpretations are just conjecture, based on how and what we think and believe in this particular time period. In actual fact, we will never know for sure the actual meanings of the particular designs, but I think it is safe to say that Irish passage tomb art was created by people capable of complex thought, and the art was important enough in meaning to expend much time and energy in the making.

- January 2005

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