Aberlady Fossil Hunting

1866 – Survey records the fossil-bearing shore
The first-edition geological survey of East Lothian recorded the fossil-bearing succession exposed along the Aberlady shore towards Craigielaw. Its descriptions of limestones, shales, sandstone and coal provided an early framework for later work on the coastal section.

1880 – Aberlady coral described
In an account presented on 14 April, James Thomson described the colonial coral Thysanophyllum orientale from a shale bed on the shore of Aberlady Bay. The description and accompanying illustrations established a documented connection between the species and this coastal locality.

1910 – Coastal succession mapped in greater detail
The revised geological survey mapped the folded and faulted coastal rocks between Kilspindie and Craigielaw and set out a four-limestone succession. This linked repeated outcrops along the shore and clarified their relationship to the surrounding shale, sandstone and coal beds.

1917 – Aberlady enters a regional correlation debate
Peter Macnair used the Aberlady shore succession in his investigation of the Hurlet Limestone and the Abden fauna. His account compared the local beds with other Scottish sections, making the shore part of a wider debate over how the Carboniferous limestones should be correlated.

1940 – Aberlady specimen selected as a coral reference
Dorothy Hill selected an original Aberlady specimen as the lectotype of Thysanophyllum orientale. This made a coral from the locality the single name-bearing reference specimen for the species, strengthening Aberlady’s place in the history of Carboniferous coral research.

1952 – Aberlady Bay becomes a nature reserve
Aberlady Bay was designated a Local Nature Reserve on 14 July. The reserve now includes the rocky shore described in this guide as well as the better-known bay habitats, placing the area’s geological interest within a wider protected coastal landscape.

1956 – Microscopic study of the shore limestones
A detailed petrographic account examined a sample from the shore east of Garlic Rock, building on the earlier survey of the Kilspindie limestones. It recorded fossil remains altered by dolomitisation, helping explain why some shells, bryozoans and crinoid fragments are preserved only as faint internal structures.

1967 – Coral growth investigated through new specimens
R. K. Jull examined newly collected examples of Thysanophyllum orientale from Aberlady, the species’ original locality. Serial sections through one colony revealed how new coral individuals developed, providing evidence used to reassess the relationships of this unusual colonial coral.

1978 – Coral communities studied bed by bed
Alistair Sutherland mapped and studied the Middle Longcraig Limestone at Aberlady, combining field observations with sections through the corals. His work showed that the coral assemblage changes through the beds, adding detail to the environmental history preserved in the limestone.

1985 – Modern survey account of the Kilspindie shore
The Haddington geological memoir brought together detailed mapping and a composite description of the Kilspindie shore. Its account placed the fossil-bearing limestones within the local sequence and explained how folding, faulting and the nearby dolerite intrusion affect the outcrops.

1993 – Microfossils add another line of evidence
Ali Mohamed Karbub included a measured section between Craigielaw and Aberlady Point in a study of Lower Carboniferous microfossils and limestone fabrics. This extended investigation of the shore from its conspicuous corals and shells to the microscopic evidence used in regional correlation.

2000–2001 – Shore incorporated into the Firth of Forth SSSI
The earlier Aberlady Bay protected area was incorporated into the enlarged Firth of Forth Site of Special Scientific Interest, notified in 2000 and confirmed in 2001. The designation provides the present statutory conservation context for the shore’s geological and coastal interests.

2014–2015 – Geodiversity value assessed
A geodiversity assessment of Kilspindie Shore recorded the importance of its fossil-bearing rocks, structures and coastal landforms for education. The field visit in 2014 and published assessment in 2015 reaffirmed the value of the exposed shore as a place to study East Lothian’s geological history.

2020 – Earlier age correlations re-examined
Pedro Cózar and Ian Somerville revisited earlier microfossil correlations in a regional study and highlighted inconsistencies in the ages previously assigned to some Aberlady beds. Their work shows why historical age schemes for this shore need to be checked against more recent evidence.

The shore section. The Kilspindie shore between Aberlady Point and Craigielaw Point exposes a folded Carboniferous succession of fossiliferous limestones, shale, siltstone, sandstone, seatearth and thin coal. This account includes the red-tiled hut, King’s Kist, Garlick Rocks, Long Craig and the western continuation towards the Gosford Bay Sill. The similarly named Craigielaw guide overlaps this same shore. Southern Gosford Bay, Ferny Ness, inland quarries and the Dunbar–Skateraw sections are separate exposures and their measured beds and fossil lists are not incorporated into this local succession.

Sedimentary cycles and age. Marine limestone and calcareous mud accumulated during incursions of the sea; mud and sand followed as the delta advanced, with rooted seatearths and thin coal recording vegetated ground and peat accumulation before renewed flooding. This is the subsiding-delta interpretation used by Duff’s field guide, rather than a claim that every cycle had one cause or preserved every component. These rocks are late Viséan, within the Carboniferous; the basal Lower Limestone succession is Brigantian. Finer ages depend on regional correlation and sparse, altered microfossils, rather than a precise numerical date measured at the guide’s reference point.

How to read the measurements. The principal succession below is described upwards, from older to younger rocks. Karbub’s sampled Aberlady section covers NT445800–455805, with a continuous Middle–Upper Longcraig portion and separately sampled Skateraw outcrops; the Survey describes a coastal composite. Sutherland’s coral observations and generalised column, and the nineteenth- and early-twentieth-century logs, are retained separately. Their measurements must not be added into a single thickness: the sources differ in exposure, subdivision and purpose, and folding repeats the same beds along the walk.

STRATHCLYDE GROUP

Aberlady Formation

Local formation and upper boundary. The Aberlady Formation is the formal local unit; the Middle Longcraig Limestone is its Blackbyre-equivalent limestone. The formation continues through the overlying shale, rooted beds and coal to the base of the Upper Longcraig or Hurlet Limestone. The Blackbyre correlation does not transfer the western Lawmuir Formation to this shore. No formal Member subdivision is required for these local beds.

Sandstone below the Middle Longcraig Limestone (about 1.2 m). Karbub records fine-grained sandstone below the basal marine shale. This is the lowest interval in his local measured account; it does not demonstrate an exposed Lower Longcraig or Hollybush limestone beneath the beach section.

Thin seatearth. An unmeasured layer separates the sandstone from the overlying calcareous shale. This fossil soil records a terrestrial interval before the marine transition; it is present in Karbub’s text although not separately labelled in his schematic log.

Basal calcareous shale (0.3 m). Dark-grey calcareous shale lies immediately beneath the Middle Longcraig Limestone in Karbub’s section. No separate species list is supplied for this particular shale.

Middle Longcraig Limestone, equivalent to the Blackbyre Limestone. This conspicuous coral-bearing limestone is exposed north-east of Craigielaw Point. Its colour varies from grey or white to yellow-brown where weathered and dolomitised. Karbub measures 3.7 m, the Survey describes about 4 m at the shore, and Sutherland gives an average of 2.5 m for his study. These independently scoped measurements are retained as observations rather than a uniform thickness range at one fixed point.

Lower bioclastic limestone (1.8 m in Karbub’s section). From the base to 1.8 m the rock is a bioclastic wackestone, a lime-mud-supported limestone containing skeletal debris. Brachiopod and crinoid fragments dominate; dolomitisation has altered most of the foraminifers, leaving only a limited identifiable microfauna.

Crystalline dolomite (1.0 m in Karbub’s section). Between 1.8 and 2.8 m above the base, the limestone becomes coarsely crystalline dolomite. Karbub could see no fossils in this interval; that observation reflects the altered rock and does not establish that the original environment was lifeless.

Upper colonial-coral band (0.9 m in Karbub’s section). The uppermost part contains colonies recorded in situ as Lithostrotion junceum and Lithostrotion pauciradiale. The corresponding modern combinations are Siphonodendron junceum and Siphonodendron pauciradiale. Duff also records both in this limestone. Bundles of corallites give the familiar spaghetti-like texture, but appearance alone cannot distinguish the species. This sampled 0.9 m band must not be equated automatically with every individual horizon in Sutherland’s separate description.

Brachiopods and other larger fossils. The Survey records abundant Composita and Pleuropugnoides in the Middle Longcraig outcrop. Its Plate 6 specifically illustrates Kilspindie specimens of Pugilis pugilis, Composita cf. ambigua and Pleuropugnoides cf. pleurodon. Duff’s historical generic list adds Eomarginifera, Spirifer, Avonia, Pustula, Composita and Pugnoides. His Caninia and Zaphrentis are old names used for solitary rugose corals, not examples of colonial corals. These locality records do not identify every unlabelled photograph to species.

Sutherland’s detailed coral horizons. Sutherland mapped the shore from Aberlady Point towards the Gosford Bay Sill, collected and sectioned corals, and published the following finer observations in 1978. They preserve changes within the Middle Longcraig Limestone and lateral occurrences across the outcrop. The names below are his identifications, with historical spellings noted where necessary, rather than a new taxonomic revision. He reported 14 rugose-coral species, including three colonial forms; that is his historical total, not a newly validated modern species count.

Basal solitary-coral horizon (average 0.5 m). The base is best seen in the anticline at NT4473 8022: grey, well-bedded limestone with brachiopods, bryozoans and solitary rugose corals. Sutherland identified Allotropiophyllum without a species name, Amplexizaphrentis curvilinea, Amplexizaphrentis enniskilleni, Claviphyllum eruca and Rotiphyllum granulare. The corals lie parallel to the bedding, generally aligned north-east–south-west. The grid reference locates the basal exposure, not every specimen in his collection.

Papery shale above the basal horizon. A thin, light-grey, fine papery shale overlies the basal limestone. It appeared unfossiliferous to Sutherland; no numerical thickness or independently gridded sample position was given.

Lighter limestone above the shale. The next limestone contains the solitary corals Amplexizaphrentis curvilinea, Aulophyllum fungites, Caninia juddi, Clisiophyllum keyserlingi, Koninckophyllum magnificum and Zaphrentites sp. Well-preserved brachiopods were recorded as Avonia sp., Productus sp., Spirifer sp. and Rhynchonella sp., together with a fenestrate bryozoan printed as Fenestalla. This last spelling is retained here as source terminology; a fenestrate fragment should not be identified to genus from its mesh alone. Sutherland supplies neither a separate thickness nor an exact grid reference for this fossil list.

Broken-colony carbonate mud. The lighter limestone grades upwards into light-grey carbonate mud containing broken Lithostrotion junceum. Sutherland tentatively attributed this mud to leaching of the upper limestone shortly after deposition; the timing and mechanism were an interpretation, not a separately measured event. No thickness was given.

White crystalline colonial limestone. Hard white limestone above the carbonate mud contains large colonies of Lithostrotion junceum, overlain by the larger colonial form he called Diphyphyllum furcatum. His general lithological description places a white crystalline exposure at NT4475 8010. A separate high-water-mark passage prints only “between NT4485-8024”, without a second endpoint; this incomplete location cannot define a surveyed range. Sutherland retained D. furcatum while discussing a proposed reassignment to Lithostrotion; it is therefore retained here as his historical identification.

Sutherland’s sectioned colonial material. For ten specimens from the white-limestone horizon, Sutherland reported an average septal count of 27, described as “of both orders”, in corallites 8 mm across, an axial tabularium 5.5 mm wide and two series of dissepiments. These anatomical observations supported his identification of Diphyphyllum furcatum and comparison with Aberlady museum material. They describe his specimens, not a universal field diagnosis or an additional measured bed.

Overturned colonies and lateral coral occurrences. At NT4460 8010, overturned colonies of Lithostrotion junceum were tentatively linked to turbulence. Sutherland recorded small, poorly preserved but identifiable Thysanophyllum orientale associated with and overlying L. junceum at NT4468 8013 and NT4487 8028; the latter specimen was left in situ. These are two documented limestone occurrences and an overturned-colony observation, not three successive measured beds or proof of a storm deposit.

Yellow dolomitised upper limestone. At NT4455 8008 Sutherland recorded a yellow dolomitised top characterised by Lithostrotion junceum and Diphyphyllum furcatum. His earlier general description also notes a yellow dolomitised top at NT4460 8010. Both local observations are retained; they do not define one universal measured top contact.

Topmost shale, seatearth and coal. A search of the topmost shale over the Middle Longcraig yielded Lithostrotion junceum and Diphyphyllum furcatum, but did not reconfirm the earlier report of Thysanophyllum orientale specifically in that shale. Sutherland’s covering sequence comprises thin papery shale, seatearth and a poor coal seam, with Upper Longcraig Limestone above at NT4452 8008. These unmeasured prose intervals are separate from the literal thickness labels on his generalised column.

The type-locality coral record. Jull’s 1967 study independently identifies Aberlady Bay as the type locality of Thysanophyllum orientale. He discusses lectotype 1095 in the Thomson Collection, and later local material RSM 1964.25, collected by C. D. Waterston and I. F. Sime, and topotype UQ F46767, collected by McDonagh. The latter supplied serial sections through six corallites. Jull’s occurrence is in shale assigned to historical Coral Zone 3; no precise modern bed or grid is supplied. It remains distinct from Sutherland’s later limestone records and his unsuccessful search of the topmost shale.

Silty shale above the coral band (1.8 m). In Karbub’s section the coral limestone is followed immediately by silty shale with limestone nodules towards its top. This local thickness is not interchangeable with the Survey’s general district interval or with a roof-shale measurement from Spilmersford Borehole.

Rooted sandstone (1.0 m). Grey sandstone, locally grading into siltstone, overlies the silty shale. Rootlets indicate the vegetated substrate developed during emergence or delta advance. No named plant species is identified in this particular bed.

Coal beneath the Hurlet Limestone. Karbub measures 0.15 m above the rooted sandstone. Duff records local development up to 0.25 m, and the BGS geodiversity audit illustrates a 0.20 m seam beneath shale and Hurlet Limestone at its exposure. These are separate local observations of the coal-bearing interval, not a uniform seam thickness across the whole shore.

Marine shale beneath the Hurlet Limestone (0.27 m). Grey calcareous shale above the coal contains bryozoan stems, crinoids, brachiopod spines and rare material printed as Stacheoides by Karbub. It records renewed marine conditions. This shale remains within the Aberlady Formation because the modern boundary is at the base of the overlying Hurlet Limestone.

Historical fish-bearing shale record. Macnair’s 1917 description explicitly reports fish remains in the awkwardly exposed shale sequence above the white coral limestone, where he also recognised apparent brachiopod and bivalve divisions. He left the presence of a distinct bone bed undetermined. The report supplies no fish taxon, abundance, specimen coordinate or measured fish-bearing sub-band; it cannot be assigned confidently to Karbub’s 0.27 m shale or used to promise modern finds.

CLACKMANNAN GROUP

Lower Limestone Formation

Boundary and limestone names. The formation starts at the base of the Hurlet Limestone, called Upper Longcraig locally. Above it, Inchinnan correlates with Lower Skateraw; Blackhall corresponds to the Middle and Upper Skateraw limestones of the regional scheme. The shore’s principal higher exposed limestone is normally called Middle Skateraw or simply Skateraw in the local descriptions. These are correlations of names, not extra superposed limestone units. Older “Lower Limestone Group” brackets do not replace the present formation boundary.

Hurlet Limestone or Upper Longcraig Limestone. The Survey coastal table records 3.6–5.5 m; Karbub measures 4.5 m in his sampled section, while the wider geodiversity audit describes a prominent 1–5 m bed across its site. Lower beds are grey, nodular, crinoidal and shelly, with colonial corals; the upper part is coarser and flaggy with thin silty bands and a reddened upper surface. Dolomitisation and recrystallisation locally obscure fossils. Duff describes pale-brown rubbly limestone below the flaggy part, with abundant crinoid fragments. His 8.5 m measurement is the relief of the scarp continuing seawards as Long Craig, not the limestone’s stratigraphic thickness.

Basal dolomitic wackestone (0–0.5 m). Karbub’s lower half-metre is dark-grey dolomitic wackestone containing crinoid debris and rare foraminifers. This is a petrographic subdivision within the limestone, not a named Member.

Light crystalline dolomite. Karbub’s detailed petrographic list places light-grey to buff, fine- to medium-crystalline dolomite at 0.5–2.5 m above the base, a 2.0 m interval. His introductory paragraph instead gives 0.5–1.5 m. The source is internally inconsistent, so the exact upper limit should not be treated as settled.

Upper dolomitic wackestone (2.5–4.0 m). The detailed petrographic list returns to dark-grey dolomitic wackestone with crinoid debris and rare foraminifers through this 1.5 m interval.

Uppermost dolomitic mudstone (4.0–4.5 m). The final half-metre in Karbub’s section is dark-grey dolomitic mudstone containing crinoid debris and brachiopod fragments.

Corals in the Hurlet. Colonial corals are not confined to the older Middle Longcraig bed. The Survey explicitly records historical Lithostrotion junceum in the lower Hurlet, and the geodiversity audit illustrates Siphonodendron junceum and the solitary rugose coral Koninckophyllum from the Hurlet. Those illustrated occurrences must remain attached to their documented bed.

Long Craig and Garlick Rocks. The limestone scarp at Craigielaw continues seawards as Long Craig. Folded and faulted Hurlet outcrops recur towards Garlick Rocks and the octagonal blockhouse, with nodular or rubbly lower beds and a flaggy upper part. Where the dip is low, the softer beds between Middle and Upper Longcraig occupy a wider outcrop. This repeated pattern does not add extra limestones to the vertical sequence.

Hurlet at Aberlady Point. An extensive limestone platform occurs to both the west and east of Aberlady Point. Duff records a local dip of about 5° south. Erosion of thin intervening shale produces the stepped limestone appearance illustrated by the geodiversity audit.

The Survey’s complete clastic interval above the Hurlet. McAdam and Tulloch’s Kilspindie coastal table preserves eight beds between the Hurlet and Inchinnan limestones. The following paragraphs follow their ascending order and measurements; together these beds total 10.33 m in that composite. This source-specific interval is considerably thicker than Karbub’s separate 1.7 m account below.

Calcareous silty mudstone (0.5 m). Immediately above the Hurlet is dark-grey calcareous silty mudstone containing occasional ironstone nodules.

Contorted sandstone (1.8 m). Yellow, fine- to medium-grained sandstone shows cross-bedding, contorted bedding, ripple marks, pyritic patches and traces described by the Survey as worm tracks. This wording does not identify every local track-maker.

Fissile mudstone (0.9 m). Soft grey and black fissile mudstone overlies the sandstone.

Flaggy sandstone (0.45 m). A pale-grey flaggy sandstone forms the next separately measured bed.

Rippled and bioturbated silty beds (3.5 m). Thinly bedded grey silty sandstone grades to silty mudstone. Ripple bedding and bioturbation preserve both physical sedimentary structures and disturbance by organisms.

Sharp-based sandstone (2.1 m). Medium-grained sandstone with a sharp lower contact weathers yellow and shows cross-bedding and ripple bedding.

Seatearth (1.0 m). This rooted fossil-soil interval lies above the sandstone and below the coal-bearing bed.

Coal and coaly mudstone (0.08 m). The thin coal-bearing interval caps this Survey cycle immediately beneath the Inchinnan or Lower Skateraw Limestone.

Sandstone and shale below the red-tiled hut. The low cliff exposes irregularly interbedded sandstone and shale within the clastic succession above the Hurlet and below the Lower Skateraw. Cross-bedded sandstone occurs near the cliff top; the shale wave-cut platform at its foot contains productid brachiopods and crinoids. The audit also describes quartz-rich fine- to medium-grained sandstone, organic patches, rippled and bioturbated surfaces, and very finely bedded black or grey siltstone locally interbedded with yellow-brown limestone across these clastic exposures. No secure evidence assigns each original photographed trace surface to an individual row of the Survey composite.

King’s Kist. East of the hut, an outlier of the cross-bedded sandstone forms the small stack known as King’s Kist, resting on undercut, more easily eroded shale. It illustrates differential coastal erosion rather than a distinct named stratigraphic bed.

Karbub’s shorter clastic account (about 1.7 m). His separately described interval above the Upper Longcraig begins with 1.0 m of dark-grey shale and 0.4 m of silty argillaceous sandstone, followed by very thin sandy shale, seatearth, about 5 cm of coal and about 2 cm of mudstone beneath the Lower Skateraw. Individual thicknesses are not given for the sandy shale and seatearth. The sandstone is also described about 27 m north-east of the separate Lower Skateraw exposure: that is horizontal separation, not an extra thickness. This account cannot substitute for, or be added to, the Survey’s complete 10.33 m clastic composite.

Inchinnan Limestone or Lower Skateraw Limestone. The Survey records 0.6–1.2 m of hard grey dolomitised crinoidal limestone containing Gigantoproductus cf. giganteus. At Duff’s western exposure immediately south-west of Craigielaw it is a well-jointed, hard grey limestone about 1 m thick with crinoids and brachiopods. Karbub’s separately sampled exposure is 0.7 m of dark-grey massive dolomitic bioclastic wackestone with crinoid and brachiopod debris; rare Endothyranopsis crassa and Palaeotextularia are recorded in his thin sections. These values describe different exposures and source scopes.

Thin beds beneath the western Inchinnan overhang. Duff distinguishes about 2 cm of mudstone over 3–5 cm of coal, with seatearth, sandy shale and sandstone below. The conspicuously cross-bedded and ripple-marked sandstone reappears about 27 m north-east of the limestone. Centimetre-scale bed thicknesses and metre-scale distances between outcrops are different measurements.

Eastern recurrence of the Lower Skateraw. East of the red-tiled hut towards Aberlady Point, the same limestone horizon reappears around the eastern syncline. Duff gives no new thickness for this occurrence; it is structural repetition, not another limestone in the succession.

Poorly exposed interval above the Inchinnan (6.1 m in the Survey composite). The Survey records an aggregate interval containing a thin coal, seatearth, pyritic silty mudstone with iron-rich nodules and micaceous sandy siltstone. Exposure is poor and separate thicknesses are not available for these components; subdividing the 6.1 m into invented measurements would give false precision.

Mudstone below the Blackhall overhang. Duff records dark-grey mudstone beneath the western limestone overhang, extensively bored by present-day molluscs. Karbub describes 0.6 m of similarly bored mudstone above his Lower Skateraw exposure. These observations of modern bioerosion in old rock do not establish that 0.6 m represents the whole Inchinnan–Blackhall interval, nor that the borings are Carboniferous fossils.

Blackhall Limestone, locally Middle Skateraw or Skateraw Limestone. The Survey’s coastal composite exposes at least 3.6 m of the lower part: hard grey, thick-bedded crinoidal limestone. Duff’s western outcrop is described as about 8 m of hard massive dark-grey, well-jointed limestone with crinoid fragments and productid brachiopods; its undulating dip surface generally inclines about 15° south-south-west. The audit likewise records Blackhall up to 8 m thick. Karbub’s separate sampled exposure is only 1.90 m and consists of grey massive, recrystallised bioclastic wackestone containing crinoid and brachiopod debris. An incomplete exposed or sampled interval must not be presented as the thickness of every occurrence.

Microfossil evidence in the sampled Blackhall. Karbub’s prose reports rare Endothyranopsis crassa and Endothyra spira, together with the alga Kamaena delicata; his age discussion also names Principia donbassica. His Middle Skateraw distribution chart marks principally Kamaena and Principia rather than independently confirming every foraminifer named in the prose. The chart/text difference and strong recrystallisation limit the precision of the local biostratigraphic interpretation.

Higher clastic beds near the western sill contact. Historical shore descriptions record dark shale and sandy bands above their Middle Skateraw limestone. The 1910 memoir adds a thin limestone at Craigielaw Point; Sutherland’s column records ferruginous nodules, ripple marks and contact alteration at Craigielaw Point. These unmeasured local beds have no separately established formal name or complete modern measured log.

Limits of the age evidence. Karbub’s older thin-section age assignments are not fully consistent between his text and figures. Cózar and Somerville’s 2020 reappraisal notes those problems and the poor Aberlady foraminiferal information. Their finer regional correlation places Middle Longcraig in the uppermost early Brigantian, but their new East Lothian samples came from Spilmersford Borehole and the Cove–Skateraw–Dunbar coast. Those offsite specimens must not become an Aberlady fossil list. Sparse genuine occurrence marks in Karbub’s local charts also do not make every printed checklist taxon a recorded local find.

Body fossils, traces and sedimentary structures. Crinoid fragments are well documented both in the limestones and in shale by the hut; this does not imply a frequency for complete articulated animals. Local sources also support brachiopods, corals, bryozoans, trails, burrows and bioturbation. Ripple marks are physical sedimentary structures and must be distinguished from traces. The available exact-shore evidence does not securely identify a trilobite maker for the photographed traces, and trilobite body fossils have not been independently verified here. That is a limit of the evidence, not proof of their absence.

Folding and faulting. The Survey locates the north-west–south-east-trending anticline crest about 250 m north-east of Craigielaw and the parallel syncline axis about 200 m south-west of Aberlady Point. These gentle folds lie on the northern limb of the broader Gosford Bay syncline. Near Craigielaw, two small north-west-trending faults raise the intervening block; Duff follows the repeated rubbly Hurlet for about 18 m along the raised bank. Another fault occurs about 70 m east of the anticline crest. The same Middle and Upper Longcraig and overlying horizons therefore recur along the coast, and the walk is not a simple continuously younging traverse.

Sandstone-filled fissures. At the anticline north-east of Craigielaw, Duff records sandstone dykes about 5–7 cm wide cutting the Middle Longcraig Limestone. These are sediment-filled fissures, distinct from the igneous sill; his brief account does not establish a unique injection mechanism.

Kilspindie cryptovent. Around 100 m east of the red-tiled hut, near the synclinal axis, a disturbed elongate structure extends roughly 100 m seawards in a north-westerly direction. Duff describes limestone fragments in broken shale, siltstone and material he termed tuffaceous. It has been interpreted as a shallow cryptovent, a disturbance associated with arrested gas or steam movement above magma. The Survey specifically notes the absence of intrusive basaltic material at Kilspindie, so this is not a demonstrated basalt-filled volcanic vent. The 100 m figures describe position and horizontal extent, not stratigraphic thickness.

Gosford Bay Sill. The igneous rock at the western end is an intrusive sill of analcime-bearing olivine dolerite or gabbro, younger than the sedimentary rocks it intrudes. It is broadly assigned to Carboniferous–Permian time by the geodiversity audit; no precise local radiometric age or sill thickness is used here. Duff’s northern contact description records baked sandstone close to the unseen contact, undulating sandstone and shale nearby, and dolerite with pale “white-trap” alteration that may mark a thin offshoot below the main sill. Near Green Craig the contact can be located to within about a metre and followed towards the Peffer Burn. These contact observations must not be confused with a large sedimentary bed or a dolerite dyke.

Alteration and mineral cavities. Dolomitisation and recrystallisation have modified the limestones and can obscure their original fossils. The geodiversity audit also records limestone cavities lined with orange-brown calcite crystals, interpreted as carbonate reprecipitated after dissolution. These mineral features are distinct from fossil coral structures.

Raised beach at Kilspindie. The Survey records 0.75 m of shelly sand and pebbles at NT4512 8028. Duff notes raised-beach material above the flaggy Hurlet about 45 m east of the octagonal blockhouse, without giving a thickness there. This younger former-shoreline deposit lies above the bedrock and its shells must be kept separate from the Carboniferous marine fauna.

Blown sand south of Craigielaw. At NT4467 7980, a peripheral superficial exposure consists of stratified blown sand with abundant comminuted shell debris and a diverse younger beach-mollusc fauna. The Survey’s main text gives about 2 m, whereas its locality note prints 0.2 cm; that unresolved source discrepancy prevents a single reliable thickness being stated. The material was interpreted as wind-blown sand derived from a sandy beach, not another Carboniferous fossil horizon.

Other superficial material. Sand, shingle and intertidal deposits cover parts of the shore and can conceal exposures. The geodiversity audit records glacial erratics of igneous rock, including mafic blocks with onion-skin weathering. Such loose blocks and young sedimentary cover belong to a separate history from the underlying limestone–sandstone cycles.

Younger shell fauna from the blown sand. The Survey’s Table 5, locality 6, records the following assemblage from the stratified blown sand south of Craigielaw. The names and abundance classes below follow the historical table, rather than a modern taxonomic revision; they are not Carboniferous occurrences. “Large numbers”, “relatively common”, and “present singly or in very small numbers” are the table’s qualitative categories. Post-mortem reworking, abrasion and leaching can affect such beach-derived assemblages.

Recorded in large numbers. Rissoa parva interrupta and Venus striatula.

Recorded as relatively common. Gastropods are Acmaea sp., Hydrobia ulvae, Littorina saxatilis, Nassarius incrassatus and Onoba semicostata. Bivalves are Cerastoderma edule, Corbula gibba, Donax vittatus, Heteranomia squamula aculeata, Heteranomia squamula squamula, Macoma balthica, Parvicardium ovale, Spisula elliptica, Tellina tenuis and Mytilus edulis.

Gastropods recorded in small numbers. Alvania crassa, Alvania punctura, Crysallida obtusa, Cingula semistriata, Gibbula cineraria, Lacuna vincta, Littorina littoralis, Mangelia coarctata, Nucella lapillus, Patella vulgata, Patina pellucida, Rissoa parva sensu stricto and Turritella communis. The table additionally marks Crysallida indistincta and Odostomia unidentata as questionable.

Bivalves recorded in small numbers. Abra alba, Abra prismatica, Chlamys opercularis, Chlamys varia, Dosinia exoleta, Hiatella arctica, Mysella bidentata, Nucula sulcata, Nucula sp., pholadacean fragments, Spisula solida and Spisula subtruncata.

Historical descriptions kept as separate records. The following source-specific columns show how the shore was described before the modern formation scheme. They retain useful small beds, fossil observations and contrasting measurements. Original feet and inches are retained in the early logs; no total is calculated across sources. Historical labels such as “reef limestone”, “daugh”, “fakes” and “fireclay” are source terminology: daugh and fireclay refer to clay-rich seatrock or rooted beds, and fakes to sandy or silty laminated beds. Correlation letters and historic rank brackets are not formal modern Members.

Sutherland’s 1978 generalised column, from bottom upwards. The map is signed 1977 and the column explicitly states that it is not to scale. It is a generalised shore composite, separate both from his detailed coral-horizon prose and from the later measured sections. All sixteen successive entries are retained below. The older age/rank brackets are not adopted as modern boundaries.

Yellow sandstone. Unmeasured sandstone at the bottom of the column, shown with a wavy basal line.

Lower seatearth (0.5 m). The column places this directly below the Middle Longcraig Limestone.

Middle Longcraig Limestone. No thickness is printed on the column; the paper’s prose gives an average of 2.5 m. The lower part is hard grey limestone with small zaphrentid corals, the middle dark grey with abundant corals and brachiopods, and the upper part hard white “reef limestone” with Lithostrotion and Diphyphyllum.

Papery rootlet shale (2 m as printed). This is the column’s shale above Middle Longcraig, labelled as thin and papery despite its printed aggregate thickness.

Upper seatearth (2.5 m as printed). A separate seatearth is shown above the rootlet shale.

Coal below Upper Longcraig. The seam is labelled thin, without a thickness.

Upper Longcraig Limestone (4.5 m). Yellow-brown crinoidal limestone, with a rubbly or nodular top in this historical column.

Yellow sandstone (2 m). The next bed above Upper Longcraig.

Sandy shale (1.5 m). Ripple-marked shale below the next coal and limestone.

Coal below Lower Skateraw. A thin, unmeasured seam.

Lower Skateraw Limestone (up to 2 m). Hard grey limestone with the historical labels Productus giganteus and Fenestella.

Coal above Lower Skateraw. A second thin, unmeasured seam, distinct from the one below that limestone.

Sandy shale with plants. Unmeasured plant-bearing shale between Lower and Middle Skateraw.

Papery shale (20 cm). A separately labelled thin shale immediately beneath Middle Skateraw.

Middle Skateraw Limestone (up to 8 m). Hard grey, thick-bedded crinoidal limestone with historical Productus giganteus.

Dark shale and sandy bands. The uppermost unmeasured entry records ferruginous nodules and ripple marks, with contact alteration at Craigielaw Point.

The 1866 Survey account. Howell, Geikie and Young describe an older eight-part coastal sequence at Aberlady, including the intrusive rock at Craiglaw Point. The sedimentary entries below follow ascending order, retaining the original item numbers from their descending list. This was a three-limestone interpretation and should not be forced into a one-to-one modern four-limestone log.

1866 item 8: Basal white limestone. White limestone rests on the sandstones and shales then called Calciferous Sandstone. No local thickness was supplied. The first limestone’s reported fauna comprises Productus sp., Athyris ambigua, Rhynchonella pleurodon, Lithostrotion junceum and Lithostrotion irregulare, all retained as historical identifications.

1866 item 7: Overlying shale (8 ft in the prose). The text gives the thickness that is absent from the numbered list.

1866 item 6: Coal and underlying fireclay. A coal seam about 10 in thick rests on fireclay above the shale.

1866 item 5: Second limestone (10 ft). Light-blue crystalline limestone rests above the coal and contains numerous crinoid remains, historical Rhynchonella pleurodon var. and Fenestella plebeia.

1866 item 4: Sandstone and shale. The unmeasured intermediate clastic beds separate the second and third limestones.

1866 item 3: Third limestone (conflicting 6 ft and 5 ft). The numbered list gives 6 ft, while the prose calls the highest limestone 5 ft thick. Both values belong to the same historical account and the discrepancy is unresolved.

1866 item 2: Upper sandstone and calcareous shale. These unmeasured beds overlie the highest limestone in the historical description.

1866 item 1: Craiglaw igneous rock. The list’s “basalt and greenstone” is intrusive context, not a youngest sedimentary bed or an extra limestone cycle.

Limits of the early fossil list. The 1866 memoir’s later fossil summary must be read by locality: records associated with its third limestone explicitly include Longniddry and Kidlaw. Those occurrences are not transferred to this shore, and the old names listed above have not all been reidentified in modern genera.

The 1910 Survey coastal table, from bottom upwards. Clough and colleagues describe the composite shore west of Kilspindie towards Craigielaw. Their A–D markers help correlate limestone horizons, rather than define new formal ranks. The thirteen entries are reproduced in paraphrase and kept separate from their neighbouring Dalskelly Crags–Ferny Ness log.

Below A (20 ft). Yellow sandstone and grey papery shale include hard white oolitic beds with rootlets.

A: Middle Long Craig Limestone (8 ft). White coral limestone contains historical Lithostrotion junceum and L. irregulare, with white marly bands and brachiopod-rich nests. One band is described as almost entirely shells of “Rhynchonella” pleurodon.

Rooted shale above A (6 ft). Grey papery shale and daugh bands contain twisted rootlets.

Coal beneath B (10 in). A separate coal seam caps the rooted interval.

B: Upper Long Craig Limestone (12–18 ft). Nodular dolomitic limestone consists chiefly of crinoid fragments; its upper part is shaly and more evenly bedded.

Fakes and shale above B (8 ft). The beds are calcareous below and sandy above, with ripple marks, numerous tracks, broken marine fossils and rolled fragments of shale and wood.

Contorted yellow sandstone (4 ft). The next sandstone has strongly contorted bedding.

Daugh and sandy fakes below C (4–18 ft). The variable-thickness interval has ripple marks and numerous tracks, without an identified trilobite producer.

Coal beneath C (3 in). A thin coal seam lies directly below the next limestone.

C: Lower Skateraw Limestone (2–4 ft). Hard grey limestone contains historical Productus giganteus.

Shale between C and D (20 ft). Grey shale contains calcareous and ferruginous oolitic nodules, some daugh-like beds and plant remains; a thin coal was seen in the Aberlady syncline.

D: Middle Skateraw Limestone (12 ft). Hard grey thick-bedded limestone contains crinoids and historical Productus giganteus. It is recorded near Craigielaw, with its base repeated in the Aberlady syncline.

Beds above D (unmeasured). Dark shale and sandy bands include a thin limestone at Craigielaw Point, contact-altered by the dolerite sill.

The 1910 appendix’s exact Aberlady list. Under “Shore, Aberlady Point. Middle Long Craig Limestone”, the memoir lists Lithostrotion junceum, unnamed turbinate corals, Dielasma hastatum, Productus aculeatus, P. muricatus, P. punctatus, P. scabriculus, P. semireticulatus, Reticularia lineata, “Rhynchonella” pleurodon, Seminula ambigua, Spirifer duplicicosta and Spiriferina cristata. These remain historical names tied to that appendix entry. Its trilobite records under other named localities do not establish trilobites at Aberlady.

Macnair’s 1917 shore log, from bed 1 upwards. Macnair’s section covers the shore north of Aberlady and west of Kilspindie to Craigielaw. The following preserves all fourteen beds and his printed imperial measurements. His historical correlation letters and regional equivalents are not used to reset modern formation boundaries or turn the local highest limestone into a modern Main Hosie assignment.

Macnair bed 1: Grey and greenish shale with yellow sandstone (20 ft). The lowest interval in his coastal log.

Macnair bed 2: White coral limestone (8 ft). His lower major limestone and the basis of his comparison with Blackbyre.

Macnair bed 3: Grey shale and fireclay (6 ft). Twisted rootlets are conspicuous in the rooted interval.

Macnair bed 4: Coal (10 in). The seam below the nodular limestone.

Macnair bed 5: Nodular dolomitic crinoidal limestone (12 ft). The prose adds that it consists chiefly of crinoid fragments, with a shaly and more evenly bedded upper part.

Macnair bed 6: Sandy black shale (8 ft). A separate clastic interval above the nodular limestone.

Macnair bed 7: Cross-bedded sandstone (4 ft). Described historically as false-bedded sandstone.

Macnair bed 8: Shale (8 ft). The next distinct shale interval.

Macnair bed 9: Coal, locally present (3 in). A thin seam developed in places below bed 10.

Macnair bed 10: Hard grey limestone (2 ft). The source records historical Productus giganteus.

Macnair bed 11: Shale (7 ft). The measured shale above bed 10; it must not be replaced by the Survey’s differently scoped 20 ft interval.

Macnair bed 12: Thin coal and fireclay (unmeasured). A separately identified rooted and coal-bearing interval.

Macnair bed 13: Hard grey limestone (12 ft). Crinoid remains and historical Productus giganteus occur in the highest major limestone; the prose notes thick bedding and the repeated base in the Aberlady syncline.

Macnair bed 14: Dark shale with thin limestone (unmeasured). The uppermost listed beds are associated with Craigielaw Point.

Using the old accounts. Their observations remain valuable, but the modern hierarchy follows the BGS Lexicon and the 1999 regional correlation table. Older coal and shale measurements differ substantially, and a historical correlation is not proof that every intervening bed was exposed or sampled at the same point. The fish occurrence belongs to Macnair’s discussion of the shale above the white coral limestone; his uncertainty concerns a distinct bone bed, not the existence of fish remains.

Jull’s local specimen detail. Lectotype 1095 was one of the Aberlady Bay syntypes and was selected by Hill in 1940, as recorded by Jull. The dolomitised topotype RSM 1964.25 could be studied mainly through polished surfaces; Jull gives corallites averaging about 20 mm and about 30 septa of each order for that specimen. These are specimen measurements, not universal species diagnostics, and an accession number is not a demonstrated collection date. His other serially studied specimen, RSM 1966.6.4 from Bathgate, is not included in the Aberlady fauna.

References

BGS Lexicon of Named Rock Units. Current entries for Aberlady Formation, Lower Limestone Formation, Blackbyre Limestone, Inchinnan Limestone, Blackhall Limestone and Lawmuir Formation. Hierarchy checked 13 October 2026.

Browne, M. A. E. and colleagues (1999). A lithostratigraphical framework for the Carboniferous rocks in the Midland Valley of Scotland, version 2. BGS Research Report RR/99/07, particularly Table 4.

McAdam, A. D. and Tulloch, W. (1985). Geology of the Haddington district. Memoir of the British Geological Survey; Kilspindie coastal section, Figure 13, Plates 5–6 and Quaternary notes/Table 5.

Duff, P. McL. D. (1996). Gosford Bay–Aberlady Point. In McAdam, A. D. and Clarkson, E. N. K. (editors), Lothian Geology: An Excursion Guide, excursion 8; the present account uses the northern sill contact and stops 4–12.

Sutherland, A. (1978). The coral fauna of the Middle Longcraig Limestone at Aberlady Bay. The Edinburgh Geologist 3, pp. 1–5, with the accompanying map, generalised column and coral sketches.

Karbub, A. M. (1993). Foraminiferal Biostratigraphy and Microfacies of the Lower Carboniferous Rocks, Central Scotland. MPhil thesis, University of Edinburgh; Aberlady section pp. 30–36, Figure 2.2, age discussion pp. 117–118 and Section 2 distribution charts.

Whitbread, K., Ellen, R., Callaghan, E., Gordon, J. E. and Arkley, S. (2015). East Lothian Geodiversity Audit. BGS Open Report OR/14/063, final version consulted; ELC_14, Kilspindie Shore, pp. 91–97.

Cózar, P. and Somerville, I. D. (2020). Foraminiferal biostratigraphy of Brigantian–Arnsbergian limestones from eastern Scotland and Northumberland (northeast England). Used for regional correlation and appraisal of older microfossil age assignments, not as a new Aberlady collecting record.

Howell, H. H., Geikie, A. and Young, J. (1866). The Geology of East Lothian. Geological Survey memoir, pp. 54 and 76.

Clough, C. T. and colleagues (1910). The Geology of East Lothian. Geological Survey memoir, coastal account pp. 139–141, Figure 7 and exact Aberlady fossil list p. 209.

Macnair, P. (1917). The Hurlet Sequence in the East of Scotland and the Abden Fauna as an Index to the Position of the Hurlet Limestone. Proceedings of the Royal Society of Edinburgh 37, section X, pp. 198–199 and Figure 4.

Jull, R. K. (1967). The hystero-ontogeny of Lonsdaleia McCoy and Thysanophyllum orientale Thomson. Palaeontology 10(4), pp. 617–628; local specimen table p. 618, discussion pp. 623–625 and Figure 5.

Aretz, M. and Nudds, J. R. (2005). Coral fauna of the Holkerian/Asbian boundary stratotype section at Little Asby Scar (Cumbria, England). Stratigraphy 2(2), pp. 167–190, particularly p. 176. Used solely for the nomenclatural link between historical Lithostrotion and the two Siphonodendron combinations.