Helmsdale’s Late Jurassic foreshore records an ancient submarine landscape beside an active fault. Its distinctive Boulder Beds contain broken shells, corals and fossil wood, together with enormous blocks of much older Devonian rock. The shore northeast of the harbour rewards careful observation, although its rocky ground and tidal headlands require planning.
FIND FREQUENCY: ♦♦♦♦ – Fossils are conspicuous in some shelly rocks, but good loose specimens are unpredictable and vertebrate remains are rare.
CHILDREN: ♦♦ – Suitable for closely supervised children on a short low-tide visit near the harbour; rough rocks and tidal pinch points make the longer shore unsuitable for casual family wandering.
ACCESS: ♦♦♦ – Harbour parking provides a nearby starting point, followed by an uneven rocky foreshore. Check local parking notices and allow ample time for the return.
TYPE: Rocky foreshore, intertidal exposures and low coastal cliffs.
DIRECTIONS
♦ Make for Helmsdale harbour from the village and use the harbour parking area, following current signs and charges. Keep clear of working harbour access, slipways and equipment.
♦ From the harbour, walk northeast onto the rocky shore. Follow this side of the coast, examining the exposed beds beyond the harbour and towards the low headlands.
♦ The shore-side road by the houses provides an alternative approach to the first part of the beach. Use an established, open access point; do not cross private gardens or assume that every road or path has a safe descent.
♦ Plan the shore walk around low tide and identify your return route before passing a headland. A path above parts of the coast may shorten the rocky return where it is open, but never rely on a higher path as an escape from an incoming tide.
♦ Reference point: 58.11951°N, 3.62861°W.
FOSSIL HUNTING
Start with the water-worn surfaces of the boulder beds close to the harbour. These hard rocks contain angular or rounded pieces of older flagstone embedded in a coarse, shell-rich matrix. Look between the large clasts rather than expecting each clast to be fossiliferous: broken bivalve shells dominate much of the surrounding material, with occasional belemnite fragments, coral and sea-urchin spines. Wave-polished surfaces often reveal these constituents better than rough, seaweed-covered rock. A hand lens is useful for examining small shell fragments and the texture of the matrix.
The fine-grained intervals offer a different search. Grey-black shale and siltstone alternate with thin, pale sandstone layers; some bedding surfaces carry plant debris, while ammonites and belemnites are recorded but should not be expected in every exposure. Thin shell-rich sandstones farther along the near-harbour shore include cidaroid sea-urchin spines. An elongated spine or a bullet-shaped belemnite fragment is a more realistic target than a complete sea urchin or a complete ammonite. Photograph fossils on their original bedding surface before considering any permitted removal, since their position is part of their scientific value.
Colonial corals occur as transported pieces within the boulder beds. Their closely packed corallites can give a honeycomb-like appearance on a weathered surface, as illustrated by the original fossil photograph below. They are evidence of animals that lived in shallower water before being carried downslope; this shore is not an undisturbed Jurassic reef. The near-harbour field description records colonies around the first prominent point, but there is no guarantee of a large loose example on a visit. Leave colonies embedded in bedrock intact rather than digging around them or hammering them out.
Calcitised conifer wood is another characteristic find. Look for an organised grain or growth-ring pattern rather than identifying every dark lump as wood. Wet specimens may appear grey or black, and their cellular detail can be hidden until examined microscopically. A small piece of loose wood collected northeast of the harbour in 2023–2024 later proved to contain fungal decay, arthropod borings and roots. Its conifer identification was tentatively Cupressinoxylon; that name cannot be applied to every piece of wood on the beach from appearance alone. Unusual wood should be photographed and recorded before preparation.
There are two different fossil ages to keep apart. Jurassic shells occur in the younger matrix and fine beds, whereas fish fragments reported from some of the large flagstone clasts belong to the much older Devonian rocks. The north-shore field account records Dipterus and Coccosteus cuspidatus in these reworked clasts. They do not identify a separate, continuous Devonian fish bed on this walk. Search naturally exposed surfaces without breaking the large blocks that preserve the evidence of their transport.
Occasional Jurassic fish debris and rare reptile remains have been reported from the north-shore succession, including crocodile, turtle and plesiosaur material. Such records do not make bones common, and an isolated tooth or vertebra generally needs specialist identification. If you find an unusual bone, a concentration of associated remains or a particularly informative piece of wood, record its position and surrounding rock and seek expert advice. Check the access-rights guidance before taking even loose specimens; this guide does not establish removal permission.
A chronological record of geological research, conservation and fossil discoveries on the shore northeast of Helmsdale harbour.
1986 – Helmsdale Coast protected as a revised SSSI
On 12 December, the coast was re-notified as the Helmsdale Coast Site of Special Scientific Interest, following earlier protection within the larger Brora–Helmsdale Coast site. The northern protected stretch includes the shore northeast of the harbour, recognising the scientific importance of its Jurassic exposures within a series of separate coastal sections.
1989 – Microfossils refine the north-shore correlations
H. F. Barron published a study of dinoflagellate cysts with positioned samples from the shore northeast of the harbour. This provided independent evidence for correlating fine-grained intervals in a succession where coarse deposits change rapidly sideways and ammonites are not present everywhere. Its historical British stage terminology requires care when comparing it with modern international ages.
2009 – Harbour-side exposures documented in detail
A. C. MacDonald and Nigel Trewin’s field itinerary described the harbour boulder beds, enormous displaced Devonian blocks, thin striped sediments, a locally 2 m thick shelly boulder bed and coral- and wood-bearing exposures towards the first point. These observations connect individual foreshore features with the processes operating beside an ancient submarine fault scarp.
2023–2024 – Loose fossil wood collected for microscopic study
Fieldwork in August 2023 and August 2024 recovered loose wood from the foreshore northeast of the harbour. One small specimen, called Helmsdale 1, contained an unusually informative mixture of altered wood, borings and roots. Its prepared sections and remaining material were accessioned into National Museums Scotland.
2025 – A Jurassic nurse-log-like interaction recognised
Ana Julia Sagasti, Sophie Burne, Jeremy Wyman and Alexander J. Hetherington described fungal decay, arthropod borings containing frass and roots within Helmsdale 1. The conifer wood was tentatively identified as Cupressinoxylon. Together, the traces show how decaying wood could support other organisms before it entered the marine fossil record. The discovery concerns preserved ecological interactions, rather than insect bodies or a fossil forest growing on the present shore.
GEOLOGY
The foreshore northeast of Helmsdale harbour exposes the Helmsdale Boulder Beds Formation, part of the Sutherland Group. Its dark fine-grained sediments, pale sandstone layers and coarse boulder-rich deposits record contrasting processes in a Late Jurassic marine basin. The formation as a whole spans the Kimmeridgian–Tithonian in the BGS scheme. Older descriptions use British ‘Upper Kimmeridgian’ and ‘Portlandian’ terminology, whose boundaries do not match the modern international stages. It is therefore misleading to label every exposure on this walk simply Kimmeridgian from the old guide alone.
An active fault separated a shallow rocky shelf from deeper water. Debris flows and rockfalls carried pieces of the shelf and fault scarp downslope, mixing older rock fragments with shells and other biological debris. Quiet-water silt and mud accumulated between the coarse events, while thin sand layers record smaller sediment movements into the basin. Reducing conditions on the deeper seabed help explain the scarcity of burrowing and of animals living directly in the fine sediment. The rich shelly debris in a boulder bed was largely transported from the shallower shelf.
Many of the largest clasts are Devonian flagstones, already ancient by the time they became incorporated in the Jurassic deposits. Near the harbour, an overturned block preserves its own older ripple lamination, cracking and other lake-sediment structures. Its enormous exposed size describes one transported piece of rock, not the thickness of a Jurassic bed. Nearby fine sediments may be distorted beneath the weight of newly deposited boulders, and some coarse beds thin out over a short distance. These changes explain why a promising rock type can disappear laterally without requiring a different named formation.
The deposits were also affected after burial and cementation. Calcite veins cutting straight through both clasts and their surrounding matrix record fractures in already hardened rock, whereas folds and faults within soft laminae formed much earlier. Later movement on the Helmsdale Fault brought the Jurassic succession against older rocks, including the Helmsdale Granite. The granite does not simply rest on top of the Jurassic beds as a normal younger layer. The foreshore photographs below illustrate the contrast between large flagstone blocks and the surrounding mixed deposits.
Detailed geology of the Helmsdale harbour-side shore: boulder beds, fine sediments and their geological history.
The descriptions below concern the shore northeast of the harbour. They distinguish individual exposures and laterally changing rock types rather than presenting a continuous measured column. The numbered localities in the scientific field guide are observation stations, not formal bed numbers; the cited sources do not identify a formal Member subdivision for these exposures.
SUTHERLAND GROUP
The BGS places the Helmsdale Boulder Beds Formation in the Sutherland Group. The group provides the regional stratigraphic context; it does not mean that every formation in the regional Jurassic succession is exposed on the harbour-side walk.
Helmsdale Boulder Beds Formation
Age and correlation. These are Late Jurassic marine deposits. BGS gives the formation as a whole a Kimmeridgian–Tithonian age range. Historical British ‘Upper Kimmeridgian’ terminology includes strata correlated with the modern Tithonian, so it should not be read as an exact equivalent of the international Kimmeridgian Stage. Published correlations near the harbour are not identical: the later field itinerary assigns the harbour to the pectinatus Zone, whereas Barron’s positioned dinoflagellate samples place nearby exposures in the historical wheatleyensis and hudlestoni intervals, approaching pectinatus farther northeast. This prevents a confident one-to-one ammonite-zone label for every visible boulder bed. The younger zonal succession towards Dun Glas belongs to a longer scientific traverse, not a measured log of the harbour-side exposures described here.
Harbour boulder beds. Near the harbour, around ND 031 151, coarse shelly sediment supports angular, subangular and rounded clasts of Middle Old Red Sandstone flagstone. The matrix is dominated by broken bivalve shells and also contains belemnite fragments, coral and echinoid spines. Angular clasts were derived from the fault scarp, while rounded examples had experienced wave action on the shallow shelf. Some clasts preserve bivalve boring cavities compared with those of Lithophaga, showing that older rock had been exposed to marine organisms before its final transport into deep water.
Giant reworked flagstone blocks. About 150 m from the harbour, the field description records one Devonian block measuring approximately 17 × 11 m in exposed area and others 5–10 m across. The large inverted block dips seawards and preserves ripple lamination, load structures, polygonal desiccation cracks and subaqueous shrinkage cracks inherited from its older lake deposits. These are clast dimensions and structures within displaced rock, not the thickness or depositional structures of the Jurassic matrix. Fish fragments in some north-shore flagstone clasts include Dipterus and Coccosteus cuspidatus; they were reworked with their enclosing Devonian rock.
Dark fine beds and centimetre-scale sands. Around ND 035 153, grey-black shale and siltstone alternate with white to pale-yellow sandstone layers up to a few centimetres thick. Grading and ripple lamination distinguish individual sand events. Their striped appearance is a descriptive sedimentary facies rather than a formal Member. The sand is interpreted as material swept from the shallow shelf and carried downslope, with storms a possible initiator. Drifted plant debris and ammonites occur in the fine beds. The lack of bioturbation, together with preserved organic matter, indicates reducing conditions at the seabed.
Lenticular boulder beds and disturbed contacts. Within that fine-grained association, individual boulder beds are lens-shaped and represent relatively small-volume flows. Some clasts exceed 1 m and protrude above the surrounding bed. The underlying siltstone and shale can be disturbed through a zone up to 10 cm thick during emplacement. The metre figure describes clast size and the centimetre figure describes a deformation zone; neither measures the full thickness of the formation. The contact evidence shows that coarse debris arrived while the finer sediment was still soft.
The locally 2 m shelly boulder bed. Around ND 038 154, a coarse boulder bed with a shelly matrix is approximately 2 m thick at the described exposure and wedges out down the beach, away from the fault. Sandstone at its top appears to drape over projecting boulders, interpreted as a compaction effect. Calcite veins running approximately parallel to the fault cut both the clasts and matrix, demonstrating that this veining followed cementation. The 2 m value is a local measurement of a laterally thinning bed, not a uniform layer extending along the whole shore.
Spine-bearing sands and carbonaceous laminae. In the next dark fine-grained interval about 100 m farther along the shore, thin bioclastic sandstones have cidaroid echinoid spines on their upper surfaces. Their long axes are aligned approximately perpendicular to the Helmsdale Fault; the animals are interpreted to have lived on the rocky shelf above the scarp. A few ammonites and belemnites occur in adjacent shale. Carbonaceous interlaminated shale and sandstone display faults and tightly folded laminae formed during sedimentation. A coarse sandstone bed wedges out downshore, and isolated boulders occur within the finer sediment.
Discontinuous beds towards the first point. The scientific exposure at Sron a Chrochair, around ND 040 155, shows abrupt lateral changes among boulder beds, sandstone and shale. About 100 m south of the point, sandstone and boulder-rich bodies locally cut across the enclosing bedding in dyke-like forms. Small sandstone dykes, disrupted shale beneath boulder beds and clasts larger than their enclosing beds provide further evidence of deformation and sediment movement. Transported colonies of the coral Isastrea, spelled Isastraea in the field guide, and calcitised conifer logs occur in this area. These observations explain the patchy outcrop; they do not establish a continuous named coral bed or bone bed.
Fossil wood and evidence from land. Wood was carried into the marine deposits from a terrestrial environment. Loose foreshore material collected northeast of the harbour in August 2023 and August 2024 included the specimen called Helmsdale 1, retained with its sections under National Museums Scotland accession NMS G.2025.5.1–5.9. Its conifer wood was tentatively assigned to Cupressinoxylon. The fragment, approximately 3 cm in diameter, preserves fungal decay, arthropod borings containing frass and small roots growing through pre-existing cavities. The authors reconstructed white-pocket fungal decay followed by arthropod boring and later root growth, supporting a nurse-log-like interaction before burial. Likely beetle and mite activity was inferred from the traces, while the roots could not be identified taxonomically. The specimen was found loose, so it cannot supply the position or thickness of an individual source bed.
Faulting, later deformation and scale. The Helmsdale Fault controlled the submarine relief and sediment supply during deposition. Later movements and fractures modified the already lithified succession, bringing it against older rocks and producing calcite veins and folds. Older granite is therefore not a younger sedimentary cap. Regionally quoted totals of hundreds of metres for the formation or more than 2 km for the wider Jurassic succession describe different, much larger stratigraphic packages. They are not measured thicknesses for this walk. The local boulder beds also do not expose the separate southern Kintradwell and Allt na Cuile successions simply because those names appear in regional diagrams.
References
MacDonald, A. C. & Trewin, N. H. (2009), Upper Jurassic of the Helmsdale area, itinerary 3.4, localities 1–4.
Barron, H. F. (1989), Dinoflagellate cyst biostratigraphy and palaeoenvironments of the Upper Jurassic of the Helmsdale region, especially the north-shore samples and correlation diagrams.
Sagasti, A. J., Burne, S., Wyman, J. & Hetherington, A. J. (2025), Decay stages of Jurassic wood debris from Scotland: evidence for the coevolution of fungal rot, arthropods and the nurse log strategy, New Phytologist.
British Geological Survey, Helmsdale Boulder Beds Formation and Sutherland Group, Lexicon of Named Rock Units.
Lathuilière, B., Charbonnier, S. & Pacaud, J.-M. (2017), taxonomic treatment of Isastrea, Zitteliana 89, 133–150, especially p. 142.
SAFETY
Visit on a falling tide with enough time to return before the water rises across the low rocky shore. The small cliffs and projecting headlands farther along the original route can become tidal pinch points. Once you round a point, the narrow part of your return route may be out of sight even while the ground around you remains exposed. Do not assume that the harbour end is safe in every tide, wave or weather condition, and do not rely on climbing the coastal bank to escape.
The foreshore is uneven, slippery with weed and broken by pools and gaps between blocks. Wear footwear with good grip, keep children close and avoid entering beneath unstable faces or climbing large fractured blocks. Give nesting shorebirds space, especially where adults are alarming or chicks may be present; turn back rather than forcing a route through them. Keep clear of harbour operations.
EQUIPMENT
Bring sturdy footwear, waterproof clothing, tide information and a charged phone. A camera, hand lens and notebook are more useful for a first visit than heavy extraction tools. Record the matrix and position of anything interesting. If you have the appropriate permission to retain small loose specimens, use padding and rigid containers for fragile shale or wood; avoid carrying heavy blocks over the slippery shore. Do not bring tools with the intention of excavating or hammering the protected exposures.
CLEANING AND TREATING
For specimens you have permission to keep, begin with photographs and a written locality record. Allow wet material to dry gradually at room temperature, supporting any thin shale or crumbly surfaces. Use a soft dry brush for loose sediment. Do not soak laminated shale or force a fossil away from hard calcareous matrix: the fossil and enclosing rock may break together.
Avoid acids, bleach, varnish and aggressive scraping. Calcitised wood, corals and shells can be damaged by chemical treatment, while grinding or polishing wood may remove the microscopic evidence that makes it scientifically valuable. Keep unusual vertebrate material or potentially informative wood unprepared and ask a specialist for advice. Consolidation should be considered only when material is genuinely unstable, using a reversible conservation treatment rather than routinely coating every specimen.
IDENTIFY YOUR FINDS
Need help identifying a fossil? Share clear photos, where you found it and its size with the community.
FURTHER READING
Geological field guide: the Helmsdale harbour-side shore (itinerary 3.4)
Jurassic wood and nurse-log-like interactions at Helmsdale
BGS: Helmsdale Boulder Beds Formation
Helmsdale Coast SSSI: official site information
Scottish Fossil Code
ACCESS RIGHTS
The shore northeast of the harbour forms part of the Helmsdale Coast Site of Special Scientific Interest. Follow the site’s current NatureScot guidance and the Scottish Fossil Code. Responsible access to look, walk and photograph is different from permission to remove fossils.
Before taking specimens, obtain the relevant landowner or mineral-rights holder’s permission and check any conditions applying to the proposed collecting. Removal permission for this route has not been established for this guide. Until it is clear, leave fossils in place and record them with photographs. Do not hammer bedrock, excavate the shore, break good coral colonies or damage protected geological features. The site’s management guidance encourages sustainable study and enjoyment while avoiding irresponsible or large-scale commercial collecting.
It is important to follow our ‘Code of Conduct’ when collecting fossils or visiting any site. Please also read our ‘Terms and Conditions‘
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