Clava Cairn

A Clava cairn is a distinctive regional tradition of Early Bronze Age megalithic funerary and ceremonial architecture clustered around the southern shores of the Moray Firth, Strathnairn, the Great Glen, Strathspey, and the Black Isle in northern Scotland (centered on Inverness-shire, Nairnshire, Moray, and Ross-shire). Named after the monumental linear cemetery of Balnuaran of Clava on a gravel terrace above the River Nairn near Culloden, roughly 50 Clava-type cairns are known across this circumscribed 60-by-45-kilometer territory. Although early 20th-century typologists grouped them with Middle Neolithic chambered cairns because of their megalithic orthostats and corbelled chambers, modern stratigraphic excavations and AMS radiocarbon dating (¹⁴C) directed by Richard Bradley (1994–1997) at Balnuaran of Clava and Newton of Petty, alongside Stuart Piggott's 1952 excavation at Corrimony, proved that the classical Clava cairns were erected in a single coherent architectural horizon during the Early Bronze Age (c. 2000–1700 cal BCE)—nearly a millennium after the heyday of Neolithic passage graves—and were later reused during the Late Bronze Age (~1100–800 cal BCE). In British archaeology and archaeoastronomy, the Clava cairns are celebrated for integrating two complementary monument forms (corbelled passage graves and unroofed ring cairns) within a shared architectural canon: a raised rubble platform, a boulder kerb graded in height from tallest in the southwest to shortest in the northeast, an outer ring of freestanding menhir-like monoliths similarly graded in height, deliberate color-coding of red, white, and black stones, and solar alignments directed toward the midwinter solstice sunset.

Within the Clava tradition—and standing side-by-side in alternating order along the cemetery row at Balnuaran of Clava—builders constructed two structurally distinct monument types that nevertheless shared identical external proportions, kerb grading, and freestanding stone circles:

1. Clava-Type Corbelled Passage Graves

Exemplified by the North-East Cairn and South-West Cairn at Balnuaran of Clava, Corrimony in Glen Urquhart, Carn Urnan on the Black Isle, and Dalcross Mains, a Clava passage grave consists of:

• Circular Rubble Mound and Graded Kerb: A circular cairn of water-worn river cobbles and glacial boulders measuring 12 to 18 meters in diameter, retained around its base by an outward-leaning ring of heavy contiguous boulder kerbstones (40 to 50 stones per circuit).
• Central Corbelled Burial Chamber: At the center of the cairn sits a circular drystone chamber (3.5 to 4.0 meters in diameter) whose basal ring of upright orthostats supports oversailing horizontal courses of flat sandstone slabs (corbelling) that originally converged upward to a beehive vault 3 to 4 meters above the floor.
• Southwestern Entrance Passage: A narrow, lintelled stone entrance passage (0.6 to 1.0 meter wide and 4 to 6 meters long) leads consistently from the southwest quadrant of the kerb into the central chamber. Unlike Neolithic Orkney-Cromarty or Maeshowe passage graves—which contained commingled ancestral ossuaries of dozens of individuals—Clava passage graves appear to have been designed for only one or two high-status primary burials: at Corrimony, Stuart Piggott discovered the crouch-buried chemical silhouette (soil stain showing high phosphate enrichment in acidic sand where bone had dissolved) of a single adult lying beneath a floor of flat stone slabs accompanied by a burnt flint flake and a bone pin.

2. Clava-Type Unroofed Ring Cairns

Exemplified by the Central Cairn at Balnuaran of Clava, Culdoich in Strathnairn, Daviot, Gask, and Newton of Petty, a Clava ring cairn shares the same circular rubble mound, graded outer boulder kerb, and surrounding ring of freestanding monoliths as a passage grave, but differs in two fundamental ways:

• Open Central Arena without a Roof: Instead of a roofed beehive chamber, the interior of the cairn is occupied by a broad, unroofed circular court (5.5 to 8.0 meters in diameter) revetted by an inner ring of closely fitted slabs.
• No Entrance Passage: The broad rubble ring between the outer boulder kerb and the inner court wall is completely continuous, with no entrance passage breaking the perimeter. Once sealed, the central court could only be entered by climbing over the rubble bank. Excavations inside the central courts of Balnuaran Central Cairn, Culdoich, and Newton of Petty recovered thick deposits of birch and hazel charcoal, burnt quartz pebbles, and scattered cremated human bone, demonstrating their use for pyre-related funerary rituals and ancestor veneration.

Richard Bradley's stone-by-stone structural and geological survey of Balnuaran of Clava revealed that the builders engineered every Clava cairn as a three-dimensional cosmological sculpture governed by five consistent design rules:

1. Southwest-to-Northeast Height Grading: In both passage graves and ring cairns, the kerbstones retaining the cairn, the orthostats forming the inner chamber, and the outer circle of 9 to 12 freestanding monoliths (set 3 to 8 meters outside the kerb) are systematically graded in height. The shortest stones (~0.8–1.0 m tall) stand on the northeast side (facing the midsummer sunrise), while stone height increases progressively around both flanks to reach maximum monumental height (2.2 to 3.1 meters tall) on the southwest side (facing the midwinter sunset).
2. External Rubble Platform / Ramp: Surrounding the outer base of the boulder kerb is a wide artificial platform or talus bank of packed cobbles (up to 4 meters wide and 0.6 meters thick). Rather than representing collapsed cairn slip as early antiquarians assumed, Bradley proved that the platform was built simultaneously with the cairn to act as a structural buttress preventing the outward-leaning kerbstones and corbelled vault from kicking out at the base, while also locking the freestanding outer monoliths upright in shallow sockets.
3. Radial Stone Causeways (Rays): At the Central Ring Cairn of Balnuaran of Clava, three low cobble causeways ("rays") radiate outward across the turf from the boulder kerb to link the cairn directly to three specific freestanding monoliths of the outer stone circle.
4. Deliberate Red, White, and Black Mineral Color-Coding: Geoarchaeological provenance mapping showed that the builders selected glacially erratic boulders and quarried Old Red Sandstone slabs according to their color and optical reflectivity:
   • Red sandstone and pink granite/pegmatite stones were concentrated in the southwest quadrant to catch and glow crimson in the low-angle rays of the setting winter sun;
   • White and sparkling crystalline quartz boulders and crushed white quartz scatters were placed in the northeast and around the entrance thresholds to reflect moonlight and sunrise;
   • Dark biotitic gneiss and black schist blocks mediated the transitional flanks.
5. Pre-Carved Cup-and-Ring Rock Art: Numerous kerbstones, passage orthostats, and chamber walls—including the famous heavily cup-marked capstone at Corrimony and hidden back-faces of orthostats at Balnuaran of Clava and Culburnie—bear pecked cup-marks and cup-and-ring motifs, some carved on living bedrock exposures before the slabs were quarried and incorporated into the cairn.

Surveyed systematically by Alexander Thom, Clive Ruggles, Douglas Scott, and Richard Bradley, the orientation of the Clava passage graves exhibits a tight non-random astronomical clustering toward the southern and southwestern horizon (azimuths between 173° and 236°). At the type-site of Balnuaran of Clava, the entrance passages of the North-East Cairn and South-West Cairn are laid out along an almost identical axis (~216°–219° azimuth). Because the two cairns are offset slightly along the terrace, an observer standing behind the cemetery at the midwinter solstice sunset (around December 21) sees the sun descend directly down the shared axis of both passages. As the setting winter sun drops to the southwestern horizon ridge, a narrow beam of orange-red sunlight penetrates the 5-meter-long low lintelled passages to illuminate the lower orthostats on the back (northeastern) wall of the dark burial chambers—precisely where red sandstone blocks were positioned to reflect the solstice light.

For over a century, the lack of surviving bronze grave goods in the acidic Highland soils led archaeologists to date Clava cairns to the Middle Neolithic (~3500–3000 BCE). In 1994–1997, Richard Bradley's excavations under the intact cobble platforms and sealed old land surfaces at Balnuaran of Clava (North-East, Central, and South-West cairns, plus the small satellite kerbed cairn of Balnuaran South) and Newton of Petty recovered stratified wood charcoal and cremated bone for AMS ¹⁴C dating:

• Primary Construction (Early Bronze Age, c. 2000–1700 cal BCE): The two passage graves, the central ring cairn, and the Balnuaran South kerbed cairn were all constructed over former agricultural clearings during the Early Bronze Age—contemporaneous with the Bell Beaker / Food Vessel transition and the neighboring Recumbent Stone Circles (RSCs) of Aberdeenshire (with which Clava cairns share graded monolith circles, ring cairns, and southwestern astronomical focus).
• Secondary Reuse (Late Bronze Age, c. 1100–750 cal BCE): After a hiatus of roughly 700 years, Late Bronze Age communities returned to the Clava monuments (at Balnuaran of Clava, Newton of Petty, and Raigmore), inserting secondary cremation burials in flat cists or pits and renewing the outer cobble platforms.

How old are the Clava cairns, and did the Neolithic or Bronze Age people build them?

Although their corbelled passages look similar to Middle Neolithic passage graves (such as Maeshowe in Orkney or Newgrange in Ireland), AMS radiocarbon dating from Richard Bradley's excavations in the 1990s proved that the Clava cairns were built during the Early Bronze Age between c. 2000 and 1700 cal BCE—making them the latest major passage-grave tradition in Britain—and were reused for cremation burials during the Late Bronze Age (~1100–800 cal BCE).

What is the difference between the three cairns at Balnuaran of Clava?

The northeast and southwest cairns at Balnuaran of Clava are corbelled passage graves with narrow southwestern entrance passages leading into formerly roofed central burial chambers. The middle monument sitting between them is an unroofed ring cairn with a broad open central court, no entrance passage, and three stone causeways ("rays") radiating outward from the kerb to three standing stones of the outer circle.

Why are the stones at Clava cairns tallest in the southwest?

Every Clava cairn is architecturally graded so that its boulder kerb, inner chamber walls, and outer circle of standing stones rise steadily from their lowest height in the northeast to their tallest height (up to 3 meters) in the southwest, framing the direction of the midwinter solstice sunset down the entrance passages.

1. Bradley, R. (2000). The Good Stones: A New Investigation of the Clava Cairns. Society of Antiquaries of Scotland Monograph Series 17. https://doi.org/10.5284/1038982
2. Piggott, S. (1956). "Excavations in passage-graves and ring-cairns of the Clava group, 1952–3." Proceedings of the Society of Antiquaries of Scotland, 88, 173–207. https://doi.org/10.9750/PSAS.088.173.207
3. Henshall, A. S., & Ritchie, J. N. G. (2001). The Chambered Cairns of the Central Highlands: An Inventory of the Structures and Their Contents. Edinburgh University Press. https://doi.org/10.3366/edinburgh/9780748614387.001.0001
4. Trevarthen, D. (2000). "Illuminating the monuments: Observation and speculation on the structure and function of the Cairns at Balnuaran of Clava." Cambridge Archaeological Journal, 10(2), 295–315. https://doi.org/10.1017/S0959774300000111
5. Ruggles, C. L. N. (1999). Astronomy in Prehistoric Britain and Ireland. Yale University Press. https://doi.org/10.1017/S0003598X00059263