John O’Groats Fossil Hunting

The low shore east of John O’Groats pier exposes a Middle Devonian fish bed within the John O’Groats Sandstone Formation. Fish scales and fragments are more likely to be recognised than complete fish, but this small protected exposure has yielded specimens of lasting scientific importance. Visit to observe and photograph its fossils and sedimentary structures.

FIND FREQUENCY: ♦♦♦♦ – Fish fragments and scales can be concentrated in particular thin layers; complete fish are uncommon and exposure depends on tide and beach cover. The rating does not imply permission to remove material.
CHILDREN: ♦♦♦♦ – The short approach suits a family visit, but children need close supervision on wet, uneven rocks. Keep to the shore above the waves if conditions are unsuitable.
ACCESS: ♦♦♦♦ – A short walk from the main visitor car park leads to the pier and adjoining shore. The fish bed is intertidal and is best observed around low water.
TYPE: Rocky foreshore with a small protected fossil-fish exposure. Plan an observation visit unless permission and any necessary consent for collecting have been arranged.

DIRECTIONS

♦ Use the main visitor car park at John O’Groats and follow the pedestrian route towards the harbour and pier. Check the parking signs on arrival.
♦ Turn east along the shore path. The guide covers the foreshore immediately east of the pier; it does not require a walk to Duncansby Head. Consult the boundary map before stepping onto the intertidal rocks.
♦ The published geological locality reference is ND 380 735. This six-figure grid reference is approximate, so use the official SSSI boundary map to check the small protected area.
♦ The original guide’s approach reference is 58.64408°N, 3.06981°W, just outside the designated strip; it is not the precise fish-bed position.
♦ Visit on a falling tide with time to return before the water rises. Stay clear of harbour operations and use a safe shore entry rather than climbing over harbour structures.

FOSSIL HUNTING

The useful starting point is the contrast between the red river-laid rocks and the much thinner grey, finely layered lake deposits. The celebrated John O’Groats Fish Bed is a light-grey laminated horizon only about 25 cm thick. Search visually along naturally exposed bedding surfaces, using a hand lens and photographs with a scale. A thin fossil-bearing layer can have a long trace across a gently dipping foreshore without being a thick bed.

Fish scales, detached bones and less identifiable fragments are a more realistic prospect than a complete animal. Within the main fish bed, the lower part is more calcareous; remains are better represented in the siltier, more distinctly laminated upper part. Look for repeated scale outlines or recognisable bone surfaces rather than identifying every shiny patch as a fossil. Pale pink or whitish marks can draw attention to a surface, but colour alone does not distinguish fish material from minerals or weathering. Photograph suspected remains both close up and in their surrounding rock.

The documented fauna includes the small armoured fish Microbrachius dicki, the larger armoured fish Watsonosteus fletti, the lungfish Pentlandia macroptera and the lobe-finned fish Tristichopterus alatus. The important distinction for a visitor is between a scale, a plate from an armoured fish, and an associated skeleton. An isolated fragment will often remain unidentified: assigning it to a species usually requires diagnostic anatomy, not simply its size or the locality. In particular, large scales should not automatically be called Tristichopterus.

Published accounts also record indeterminate Dipterus material, whereas the BGS’s 2005 fauna summary lists four named species. The assemblage is less diverse than those of older Caithness fish beds. Its scientific value lies partly in preserving a younger, distinctive assemblage, including material on which three species were originally described.

There is more to recognise than the main fish bed. The measured section includes a higher, dark-grey laminated layer, about 20 cm thick, with fish fragments, scales and coprolites. Thin dolostone bands, ripple-marked surfaces, polygonal drying cracks and contorted lamination help explain the changing lake-margin setting. These features can be recorded without opening fresh rock. The higher fragment-bearing layer must not be confused with the named 25 cm bed, and the local fault means that a horizon may be offset across the shore rather than continuing in a straight line.

Do not use a pick to open the in-situ fish bed or remove large blocks. The protected exposure is small, erosion is slow, and unrecorded extraction can destroy relationships that make a specimen scientifically useful. Pedestrian access is not collecting permission. Without agreed permission, leave material in place and take photographs; if a convincing articulated fish or unusual specimen is exposed, record its position and contact NatureScot or a museum before attempting recovery. A naturally detached block is not automatically free to take.

A chronological record of significant fossil discoveries, geological research and conservation at the John O’Groats fish bed.

1861 – Tristichopterus alatus described
Philip Egerton described Tristichopterus alatus from specimens found by Charles William Peach at John O’Groats. The incomplete original material left important questions about its head, teeth and paired fins.

1867–1868 – Peach reports a small armoured fish
Peach presented a record of the small fish later named Microbrachius dicki at the 1867 British Association meeting; the report appeared in 1868. His proposed name commemorated Robert Dick. This is a report and publication date, rather than a securely established year of collection.

1875 – The anatomy of Tristichopterus reconsidered
Ramsay H. Traquair published a detailed study of the structure and affinities of Tristichopterus alatus, revisiting the uncertainties surrounding the John O’Groats material and its relationship to other Devonian fishes.

1888 – Microbrachius formally distinguished
Traquair described Peach’s small armoured fish, by then in the Edinburgh museum collections, as Microbrachius dicki. John O’Groats became the type locality for this distinctive antiarch.

1888–1889 – A distinct John O’Groats lungfish
Traquair separated the local lungfish from Dipterus valenciennesi in 1888 and published a fuller illustrated description in 1889. His figures included a shoulder girdle and pectoral fin that would become important in much later anatomical research.

1891 – Type specimen selected
Arthur Smith Woodward selected the articulated lungfish figured by Traquair as the name-bearing type of the species now called Pentlandia macroptera.

1914 – Geological Survey account distinguishes the fossil horizon
C. B. Crampton and R. G. Carruthers documented the thin flagstone band near the John O’Groats Hotel and its distinctive fish fauna. Their account distinguished it from other bands farther east along the coast.

1916 – Pentlandia established
D. M. S. Watson and H. Day recognised that the John O’Groats lungfish belonged in a separate genus and introduced Pentlandia.

1972–1974 – Sedimentary setting and fish-zone framework
Work by R. J. Foster, followed by the regional stratigraphic synthesis of R. N. Donovan and colleagues, placed the fish bed in the Last House succession and the highest Middle Devonian fish zone recognised in Caithness. The river-dominated setting, interrupted by lake deposits, explained its contrast with older, richer fish beds.

1987 – The small shore exposure protected
John O’Groats was notified as a Site of Special Scientific Interest on 28 September 1987 for its fossil-fish interest. Protection concerns a defined intertidal strip east of the pier, rather than the entire surrounding coast.

1999 – A detailed measured section published
The geological conservation account published M. A. Rowlands’s bed-by-bed log, documenting the 25 cm fish bed, the thinner units around it and a separate higher layer containing fish fragments, scales and coprolites.

2008 – Site management focused on retaining the exposure
The revised management statement emphasised keeping the rock exposures accessible, preventing damage from dumping or construction, and promoting responsible study through the Scottish Fossil Code.

2014 – A historic lungfish fin examined with modern imaging
Emma Jude, Zerina Johanson, Anton Kearsley and Matt Friedman re-examined the John O’Groats specimen NMS 1875.29.45. Its unusually informative pectoral-fin skeleton helped clarify early lungfish fin anatomy and comparisons with living forms.

GEOLOGY

The shore belongs to the John O’Groats Sandstone Formation, which the current BGS Lexicon assigns to the Eday Group and the Givetian Stage of the Middle Devonian. Older accounts use John O’Groats Sandstone Group and place the fish bed in the Last House Formation. These are different naming schemes for the succession, not three separate rock units to stack above one another. The regional sandstone succession is hundreds of metres thick; only a small part around the fish bed is relevant to this short shore visit.

The red and buff sandstones record streams crossing a low-gradient alluvial plain or fan. Inclined sets of lamination formed as sand moved through channels, while mud accumulated between stronger flows. Some soft sediment was distorted before it hardened, producing folded or convoluted lamination and water-escape structures. Drying cracks show that wet sediment surfaces were repeatedly exposed. Immediately east of the harbour, published descriptions record sandstone beds up to about 50 cm thick, with cross-bedding, parallel lamination and ripple cross-lamination.

At intervals, lake water spread across this river-dominated landscape. Fine silt and carbonate settled in thin layers, creating the grey laminites in which fish remains were preserved. The contrast is visible at the scale of a hand specimen: relatively massive or cross-bedded river deposits give way to finely layered lake sediments. The main fish bed becomes less calcareous and more silty upwards, with better-developed lamination and more fish material towards its top. Its unusual fauna records a later phase of the Orcadian lake system than the better-known older fish beds of Caithness.

The beds dip about 20° towards the east-north-east. A north-east–south-west fault with a recorded downthrow of about 3.5 m displaces the fish bed towards the north-east on the seaward part of the shore. This structure, together with the tidal exposure and shifting cover, explains why tracing a thin layer can be confusing.

Explore the geological framework and the measured beds around the John O’Groats Fish Bed.

This account is confined to the foreshore east of the pier around ND 380 735. The sequence below follows M. A. Rowlands’s measured section as published in the geological conservation account, from youngest at the top to oldest at the bottom. Thicknesses belong to that measured section and are not guarantees of what will be uncovered on a particular visit.

EDAY GROUP

The current BGS classification places the John O’Groats Sandstone Formation in this group. Comparable fish-bearing deposits occur in Orkney, but those successions and their measurements are not reproduced as beds exposed on this shore.

John O’Groats Sandstone Formation

Age, names and limits. The formation is Givetian. Historical literature uses John O’Groats Sandstone Group and Last House Formation for the fish-bed succession. The BGS’s approximately 609 m formation thickness is regional, not the height of this exposure. Its regional lower-boundary definition and the fault-bounded relationships described in the conservation account do not establish a visible basal contact at the fish bed.

Red mudstones and coarse siltstones — 3 m. The highest interval in the published local log comprises red mudstone with coarser siltstone, interpreted as river-laid sediment. It caps the thinner, partly lacustrine succession described below.

Pink-weathering convoluted siltstone — 0.6 m. Distorted lamination records deformation of soft sediment.

Fining-upwards red mudstones — 0.75 m. This red interval lies between the convoluted siltstone above and the dark lake laminite below.

Upper dark-grey lacustrine laminite — 0.2 m. This finely layered lake deposit becomes siltier upwards and contains numerous fish fragments, scales and coprolites. It is distinct from the named John O’Groats Fish Bed lower in the section.

Green-grey mudstone — 0.01 m. A one-centimetre muddy layer immediately underlies the upper fish-fragment-bearing laminite. Its small thickness is retained because it helps distinguish that higher horizon from the main fish bed.

Hard light-grey dolostone — 0.02 m. This two-centimetre carbonate bed separates the green-grey mudstone above from red and green mudstone below. It should not be mistaken for the thicker, laminated main fish bed simply because both can appear light grey.

Red and green mudstones — 0.04 m. A thin, colour-varied muddy interval sits between the hard dolostone and the underlying dolostone-banded siltstones.

Dark-grey laminated siltstones with dolostone bands — 0.37 m. These laminated sediments lie immediately above the named fish bed. Their alternating silty and carbonate-rich layers form part of the local lake-deposit package.

John O’Groats Fish Bed — 0.25 m. The principal horizon is a light-grey varved laminite, with more carbonate towards its base. Fish scales, fragments and occasional complete individuals are more frequent in the upper, siltier, better-laminated part. The bed is approximately 25 cm thick. This is the lowest of the three thin carbonate-laminite horizons identified in broader accounts of the local succession.

Convoluted laminated siltstone — 0.1 m. Directly beneath the fish bed is a ten-centimetre layer with mudcracks and a coarse-siltstone dyke. The dyke cuts within soft sediment; it is a sedimentary feature, not a volcanic intrusion.

Grey siltstone — 0.02 m. A two-centimetre siltstone layer separates the convoluted bed above from the darker calcareous siltstone below.

Dark-grey calcareous laminated siltstone — 0.03 m. This three-centimetre carbonate-bearing layer overlies the bituminous shale. Its dark colour and fine layering belong to the lower fine-grained package around the fish bed.

Soft bituminous shale — 0.07 m. A seven-centimetre, organic-rich shale occurs beneath the calcareous siltstone. Its softness contrasts with the overlying, more calcareous siltstone.

Dark-grey siltstones with green muddy interbeds — 0.08 m. This thin package alternates dark siltstone with green mudstone and siltstone. Desiccation cracks occur in its upper part, recording exposure and drying before the overlying sediments accumulated.

Lower red mudstones and pink siltstones — more than 10 m. The base of the published local log comprises alternating red mudstone and thin pink siltstone beds, the latter around 50 mm thick. These are interpreted as river deposits. The “10+ m” figure describes the recorded lower interval, not the thickness of the whole formation and not a measured formation base.

Exposure and interpretation. The local succession records river deposition repeatedly interrupted by lake expansion, shallow-water sedimentation and drying. Polygonal cracks, ripple structures and contorted lamination can be studied alongside the fossils. The 20° east-north-east dip and the faulted offset must be allowed for when relating adjacent rock surfaces; a line across the beach is not automatically a simple bed-by-bed traverse. The conservation account places the assemblage in Donovan and colleagues’ Faunal Zone 7, of mid- to late Givetian age, and correlates it with the Eday Flags of Orkney and Brindister Flags of Shetland. Those are correlations between areas, not extra local beds. Neither the complete Eday succession nor the adjacent Duncansby geology is exposed in this single measured log.

References

British Geological Survey, John O’Groats Sandstone Formation (JOG) and Eday Group (EDY), Lexicon of Named Rock Units.
Dineley, D. L. and Metcalf, S. J. (1999), Fossil Fishes of Great Britain, Geological Conservation Review Series 16, John O’Groats account, pp. 216–218, including M. A. Rowlands’s measured section.
Barclay, W. J. and colleagues (2005), The Old Red Sandstone of Great Britain, Geological Conservation Review Series 31, John O’Groats account; only its harbour-side observations are applied here.
Newman, M. J. and Dean, M. T. (2005), A biostratigraphical framework for geological correlation of the Middle Devonian strata in the Moray-Ness Basin Project area, BGS report IR/05/160, section 4.5.
Crampton, C. B. and Carruthers, R. G. (1914), The Geology of Caithness, Geological Survey memoir, p. 57.
NatureScot, John O’Groats SSSI, citation, boundary map and site management statement, site 824.

SAFETY

Check local tide times and the marine weather before visiting. The fossil exposure lies between high and low water; allow a generous return margin and do not follow a bed into waves or deeper water. The nearby Pentland Firth is an exposed marine setting, so a low predicted tide does not make a rough day safe. Keep a clear route back to the shore.

Wear footwear with good grip. Seaweed-covered slabs, wet rock steps and loose blocks can be slippery, and cracks between blocks can trap a foot. Keep children close, avoid climbing harbour walls and stay away from working boats and access routes. Wind and cold can become uncomfortable quickly even on this short walk.

EQUIPMENT

Take a hand lens, camera or phone, a small photographic scale, notebook, tide information, grippy footwear and weatherproof clothing. A close photograph that includes the surrounding bedding is often more useful than an isolated close-up. A pick, hammer or chisel is not appropriate for an unpermitted visit to the protected fish bed. If an authorised scientific collection has been arranged, follow its agreed methods and recording conditions.

CLEANING AND TREATING

Leave in-situ fossils and their surrounding rock undisturbed. For any specimen lawfully collected under the necessary permission, retain its precise locality, bed and collection details, together with photographs taken before removal. Keep associated pieces and any counterpart together. Support laminated material in a rigid box rather than allowing slabs to rub against one another.

Let damp material dry gradually at room temperature and begin with gentle dry brushing only if the surface is stable. The fish may be flattened within fine, carbonate-bearing laminae, so forcing a split or scraping a pale patch can remove the evidence you are trying to reveal. Avoid acids, bleach, varnish and routine soaking. Leave a potentially complete or unusual specimen unprepared until a specialist has advised on its identification and conservation.

IDENTIFY YOUR FINDS

FURTHER READING

Deposits: Fossil fishes of the Old Red Sandstone (regional background including John O’Groats)
Geological Conservation Review: John O’Groats fossil fishes and measured section
BGS: John O’Groats Sandstone Formation
Jude and colleagues: the pectoral fin of Pentlandia macroptera from John O’Groats
NatureScot: John O’Groats SSSI information and documents
Scottish Fossil Code and guidance

ACCESS RIGHTS

Part of this shore is John O’Groats SSSI. The designated site is a small intertidal strip immediately east of the pier, approximately 100 m along the shore; it does not cover the whole visitor area or the entire coast to Duncansby. Consult the official boundary map. Its fossil bed is of international scientific importance, and the management guidance seeks to retain the exposure and prevent damaging or large-scale collecting.

Scotland’s outdoor access rights do not give a right to extract rock or fossils. Obtain the landowner or occupier’s permission, the mineral-rights owner’s consent where relevant, and establish any necessary NatureScot consent before sampling. Do not hammer protected bedrock without consent. The site’s published Operations Requiring Consent list specifies dumping, spreading or discharging material; that list is not itself collecting permission. For an ordinary visit without agreed permission, observe and photograph, leave fossils where they are, and avoid disturbing the bed.

Scotland’s fossil resource is at risk of abuse and damage, and so we must all safeguard and managed fossil collecting to ensure its survival for future generations. For this reason it is VITAL you read and adhere to the Scottish Fossil Code for ALL sites in Scotland. 

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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