Elgol Fossil Hunting

This history distinguishes the village shore and shell bay from the broader Carn Mor–Glen Scaladal vertebrate localities and the distant North Elgol marine section. Later anatomical research often concerns specimens collected decades earlier.

1910 – Geological Survey mapping and published account of the Jurassic succession
Wider North Elgol Coast. Wedd’s Survey account is an early documented stage of work on the local marine succession. This is an early documented account, rather than a claim to the first discovery of fossils here.

1964–2010 – Elgol Coast protected as an SSSI
Elgol Coast was notified in 1964 and 1974, with later reviews on 10 April 1990 and 15 December 2010. The protected strip contains distinct Bathonian, Callovian, Oxfordian and Mesozoic mammal interests; it is broader than the first shell bay.

1966–1970 – Turner studies and Hudson & Morton field guide
North Elgol Oxfordian and Glen Scaladal. Established local succession and sedimentological interpretations. Hudson’s 1969 guide specifically drew attention to bone fragments in the Ostracod Limestones at Glen Scaladal, encouraging the later vertebrate discovery.

August 1971 – Recognition of important vertebrate locality by Michael Waldman and J. B. Dobinson
Cladach a’Ghlinne / Glen Scaladal wider Elgol coast. Discovery opened systematic research on one of the rare rich Middle Jurassic small-vertebrate assemblages. Waldman and Robert Savage undertook seven field trips in 1971–1982.

1972 – Borealestes serendipitus and Stereognathus hebridicus described
Wider Elgol Kilmaluag Formation. Waldman and Savage established the docodont mammaliaform Borealestes and named the local tritylodont material. The tritylodont is a non-mammalian cynodont; its name was later synonymised with Stereognathus ooliticus.

1973–2025 – Elgol partial dinosaur skeleton: discovery, rediscovery, recovery and publication
South Carn Mor sector of the wider Elgol coast, Kilmaluag Vertebrate Beds. Savage’s notebook records discovery on 21 May 1973. Stig Walsh and Richard Butler relocated it in 2015; an Elsa Panciroli-led team recovered it in April 2018. The 2025 paper confirms Scotland’s historically first definite dinosaur body fossil and most complete partial dinosaur skeleton then known. NMS G.2023.19.1. Its cerapodan, probably ornithopod, affinity remains tentative; no new dinosaur species was named.

1973; studied in 2021 – Associated Borealestes skeleton acquired during early campaigns
Wider Elgol Kilmaluag coast. NMS G.1992.47.121.1 later enabled cranial and postcranial reconstruction that isolated teeth could not supply. The specimen was collected in 1973; the 1992 accession prefix does not date its discovery.

1975–1979 – Modern marine lithostratigraphic and ammonite revisions
Distant North Elgol Coast and Carn Mor marine succession. Sykes (1975) defined/revised Staffin Bay/Shale local members; Sykes & Surlyk (1976) and Sykes & Callomon (1979) developed correlations and ammonite zonation. These revisions concern the separate marine coast, not the first lagoonal shell bay.

1980 – Great Estuarine Group formal lithostratigraphy
Elgol type sections and regional context. Harris & Hudson formalised the group and seven formations; Elgol is type locality of Cullaidh Shale and Elgol Sandstone, and Glen Scaladal a partial type section for Kilmaluag. Kildonnan and Lonfearn are Lealt members.

1984–1986 – Detailed logged sedimentology of upper Great Estuarine units
Elgol–Glen Scaladal composite sections. Andrews distinguished late Bathonian lagoonal regression, the Kilmaluag Vertebrate and Breccia Beds, desiccation/dolomitisation and transition to Skudiburgh alluvial deposits. The Vertebrate and Breccia Beds remain informal bedsets, not formal members.

1986 – Detailed excursion account made local beds and fossils accessible
Strathaird including Elgol. Bell & Harris documented short Lealt and Kilmaluag bed lists, fossil assemblages and later igneous overprinting. The numbering in this historical excursion is independent of the later measured logs.

1989 – Elgol Sandstone delta sedimentology
Elgol Sandstone type locality. Harris’ facies study interpreted coarsening-upward prodelta/delta-front/distributary-mouth-bar sandstones and shoreline advance; local cross-bedding and rootlets constrain environment.

1990 – Duntulm facies and composite section revision
Elgol and Glen Scaladal. Andrews & Walton logged oyster-rich limestones, argillaceous limestones and algal horizons, demonstrating shallow lagoonal shell-bank and interbank environments. The composite section contains 17 m of observed strata and an intervening gap, rather than one uninterrupted exposure.

1991 – Conchostracan taxonomy and palynological studies
Local Great Estuarine sections with regional comparisons. Chen & Hudson documented clam-shrimp faunas, including rare Cullaidh and Lealt records at Elgol; Riding and colleagues studied age/environmental palynology. Local heating has damaged palynomorph preservation, so regional microfossil lists cannot simply be applied to every Elgol bed.

1992 – Valtos delta-system and marginal-facies interpretation
Elgol Valtos compared with northern Skye/Eigg. Harris explained the unusually thin, carbonate-rich marginal-basin expression at Elgol, including mudflat emergence and brackish transgression. The unusually thin local carbonate-rich unit differs from the thick sandstone development farther north on Skye.

1994–1996 – Early detailed reptile descriptions
Wider Elgol Kilmaluag fauna. Waldman & Evans described lepidosauromorphs including Marmoretta; Evans & Waldman and related work expanded recognition of salamanders, small reptiles and crocodylomorph material. Some preliminary classifications were subsequently revised.

1994–1995 – Ostracod study and detailed Elgol Lealt log
Elgol Lealt Shale and regional Great Estuarine Group. Wakefield’s work supplied a bed-numbered local log and microfaunal ecological evidence used in the GCR account. This local log uses numbering distinct from Morton and Hudson’s later Table 1.

1995 – Comprehensive modern Jurassic field guide and measured Elgol table
Core Elgol and wider coast. Morton & Hudson published full local narrative, 81 individually numbered bed/sub-bed entries for upper Kildonnan, Lonfearn and lower Valtos, plus separate Valtos/Duntulm/Kilmaluag logs. The table covers a measured interval, not a complete continuously exposed Great Estuarine Group.

2001–2002 – GCR conservation syntheses recognised the two distinct stratigraphic sites
North Elgol Coast; Elgol–Glen Scaladal. Wright’s Upper Jurassic and Cox’s Middle Jurassic chapters explain type/reference sections, environmental interpretation and international scientific significance. The Oxfordian North Elgol section and Middle Jurassic Elgol–Glen Scaladal section have distinct geological scopes.

2003 – Breccia-bed ichnology revised
Wider Strathaird Kilmaluag Formation. Marshall studied Psilonichnus-ichnofacies traces and desiccation-related decapod burrows, refining interpretation of lagoon-margin environments. This is wider Strathaird context, not a confirmed identification of each tubular mark in the village-shore photographs.

2004–2009 – Eileanchelys waldmani named and described
Cladach a’Ghlinne / Glen Scaladal, Kilmaluag Formation. A partial skull and a block with at least five, perhaps six turtles revealed a stem turtle with intermediate cranial features; aquatic ecological interpretation was important for early turtle history. Holotype NMS G.2004.31.15. Collection was in 2004, online publication on 18 November 2008 and the journal issue on 7 March 2009; the taxonomic authorship is 2009.

2006–2007 – First described Scottish dinosaur tooth
Strathaird Kilmaluag, wider Elgol assemblage. Barrett described sauropod tooth NMS G.2004.31.1; morphology supports a basal eusauropod or basal titanosauriform affinity. The tooth is not securely assigned to a genus, and its accession year alone does not establish when it was found.

2006–2024 – Ceoptera evansae pterosaur discovered and named
Cladach a’Ghlinne wider Elgol coast. Partial associated skeleton NHMUK PV R37110 found on a museum/university field trip; 2024 description added a Middle Jurassic darwinopteran and evidence of greater pterosaur diversity. The partial skeleton was found in 2006 and named on 5 February 2024. It is distinct from Dearc at Brothers’ Point.

2012 – BGS stratigraphical framework consolidated nomenclature and thickness conflicts
Elgol within Hebrides Basin. Barron, Lott & Riding formally summarised units, parents, definitions and reference sections, explicitly retaining local thickness uncertainties.

2014 – New dinosaur and crocodylomorph specimens described
Strathaird Kilmaluag, wider Elgol assemblage. Wills, Barrett & Walker described an indeterminate dinosaur femur, theropod tooth and goniopholid material, expanding rare large-vertebrate records. These separate specimens are not the associated skeleton described in 2025.

2015–2016 – Palaeoxonodon jaw revised tooth-based taxonomy
Wider Elgol Kilmaluag coast. Close and colleagues’ near-complete jaw NMS G.2015.17.1 showed that variation along one tooth row could explain teeth formerly named as separate taxa. Palaeoxonodon ooliticus was originally named from English material; this study did not name a new Elgol species.

2017 – Wareolestes rex jaw and tooth replacement
Wider Elgol Kilmaluag coast. Panciroli, Benson & Walsh described NMS G.2016.34.1, an erupted/unerupted tooth-bearing jaw; CT evidence supported a two-generation premolar replacement pattern. The jaw came from a fallen block assigned to Kilmaluag through its lithology and setting. The species had originally been named from English teeth.

2017 – Stereognathus species synonymy
Elgol type material compared with English collections. Reassessment concluded Scottish S. hebridicus could not be maintained as distinct from S. ooliticus. This was a taxonomic revision of existing material, not a new field discovery.

2018 – Additional Palaeoxonodon dentaries described
Cladach a’Ghlinne wider Elgol coast. New partial jaws provided additional anatomical information on the early cladotherian P. ooliticus. Includes NMS G.1992.47.123 and NMS G.2017.37.1. New material collected in 2017 was described in 2018; the older specimen’s accession number does not date its discovery.

2018–2019 – Borealestes ear bones and mandible studied
Wider Elgol Kilmaluag fauna. Petrosal/stapes and jaw studies increased anatomical knowledge of early docodont hearing and dentition using old and new specimens. The ear study appeared online in 2018 and in a 2019 issue; related mandibular work followed in 2019.

2018–2021 – Borealestes cuillinensis and revised skull anatomy
Cladach a’Ghlinne wider Elgol coast. A second local Borealestes species, holotype NMS G.2020.4.1.1 found by Richard Butler, helped resolve cranial anatomy and differences from B. serendipitus. Richard Butler found the holotype in 2018; naming followed on 27 January 2021, independently of its 2020 accession number.

2019–2020 – Additional protection for vertebrate fossils
The Skye Nature Conservation Order took effect on 1 August 2019 and was confirmed on 14 January 2020. Elgol is expressly included, protecting vertebrate body and trace fossils in the rocks, beach deposits and cliff falls.

2020 – Comprehensive Kilmaluag vertebrate assemblage review
Mainly Elgol–Glen Scaladal, with explicitly separate other Skye records. Panciroli and colleagues synthesised fish, amphibians, reptiles and mammaliaforms; explained exceptional associated skeleton preservation and global Middle Jurassic importance. The broader review also discussed other Skye sites, whose insects and footprints must not be relocated to Elgol.

2021 – Marmoretta skull reinterpreted using micro-CT
Wider Elgol Kilmaluag coast. Griffiths, Ford, Benson & Evans reconstructed previously hidden cranial anatomy and recovered Marmoretta as a stem lepidosaur, refining early lepidosaur evolution. This was a reanalysis of historical material, not a new 2021 discovery or naming.

2021–2022 – Borealestes locomotor ecology reassessed
Wider Elgol skeletons of both species. Postcranial study supported a relatively generalised animal lacking the extreme specialisations of some Chinese docodonts, although capable of scratch-digging and perhaps swimming. Published online on 1 December 2021 and in the 2022 volume, the results favour a relatively generalised ecology rather than an unqualified burrowing specialist.

2022 – Marmorerpeton wakei named
Wider Elgol Kilmaluag coast. Jones and colleagues combined historical and new material, including a 2016 associated skeleton, revealing early stem-salamander anatomy and supporting placement in Karauridae. Holotype NMS G.2021.4.3. The 11 July 2022 study combined material collected in 1971 and 2014–2019, including a 2016 associated skeleton. Older Skye records should not all be assigned automatically to Marmorerpeton kermacki.

2022 – Near-complete Bellairsia gracilis skeleton
Wider Elgol Kilmaluag coast. Tałanda and colleagues used synchrotron tomography of NMS G.2022.1.1 to clarify stem-squamate anatomy from an exceptionally complete small skeleton. The Scottish skeleton was discovered in 2016 and described in October 2022. The species itself had been named from English material in 1998; it is not claimed as a literal direct ancestor of living lizards.

2024 – Adult and juvenile Krusatodon reveal prolonged growth
Elgol Coast Kilmaluag Formation. Panciroli and colleagues used CT-based tooth cementum growth increments: adult about seven years old; juvenile conservatively 7–24 months, still replacing teeth. Demonstrates a slower life history than living small mammals of comparable mass. The adult was collected in the 1970s and the juvenile in 2016; publication followed on 24 July 2024. These are estimated ages and a biological interpretation for the studied animals, not proof of the same growth pattern in all Jurassic mammals.

2025 – Marmoretta postcranial anatomy supports clinging arboreality
Wider Elgol historical specimen. Ford and colleagues studied NMS G.1992.47.1 using CT and comparative hand morphology, favouring climbing/clinging ecology over older semi-aquatic interpretations. Published on 16 April 2025, this re-study of a specimen first described in 1994 supports, rather than directly observes, climbing behaviour.

2025 – Breugnathair elgolensis named
Elgol Coast SSSI, Kilmaluag Formation. Stig Walsh found holotype NMS G.2023.7.1. Benson and colleagues demonstrated one parviraptorid individual combined snake-like teeth with other primitive squamate features, clarifying previously puzzling isolated fossils. The partial disarticulated skeleton was found in March 2015 and named on 1 October 2025. Its phylogenetic position remains uncertain: it is not securely a snake or direct snake ancestor.

2025 – Eileanchelys neuroanatomy reassessed
Cladach a’Ghlinne holotype in museum collection. Ferreira & Evers digitally reconstructed braincase, nerves and inner ear; results document early turtle cranial transitions and independently support aquatic adaptation in Eileanchelys. Published on 11 November 2025, this was a new study of the holotype collected in 2004, not a newly found Elgol turtle.

Geographical scope. The succession below is described upwards, from older to younger rocks, but it is not one continuously exposed beach section. The main Elgol visit concerns the Elgol Sandstone cliffs, the Lealt Shale shell-rich bay and the lower Valtos continuation. The Cullaidh Shale at Port na Cullaidh is variably exposed and may be outside a harbour-to-north-only walk. Older Bearreraig rocks lie farther south. Duntulm, Kilmaluag, Skudiburgh and the overlying marine sandstone belong to the wider Carn Mor–Glen Scaladal coast, with separate sections, faults, intrusions and a major landslip. The distant North Elgol Oxfordian section is described separately at the end; its geology must not be treated as the shell bay’s fossil assemblage.

Dip, folding and interruption of the section. Across the broader coast, the Jurassic beds generally dip gently west-north-west and young from south to north, although folding repeats parts of the succession farther north. Small faults and intrusions complicate individual exposures, and the Carn Mor landslip interrupts the coastal section. These structures explain why apparently neighbouring rock faces cannot always be joined into one measured column.

How to read the section. The Great Estuarine Group comprises seven formations here. Bearreraig Sandstone, Staffin Bay and Staffin Shale are separate formations outside that group. Amber bars identify the group, orange bars formations and pale-cyan bars members; numbered beds and informal fossil-bearing horizons are subordinate descriptions. Local measurements are distinguished from district estimates, incomplete exposures and gaps. Numbers restart in each member, formation or independently published log.

The measured main-bay beds. Morton & Hudson’s 1995 Table 1 provides the detailed main-bay log reproduced in descriptive form below: 22 numbered Kildonnan beds or sub-beds, 47 Lonfearn beds and 12 lower Valtos beds, plus four unexposed intervals and one sill. The table begins above the Lealt formation base and ends below the Valtos top. Its 81 numbered entries therefore do not constitute a complete thickness measurement of either formation. Historical fossil identifications and the source’s qualifications are retained.

Bearreraig Sandstone Formation

This older marine formation is represented south of Port na Cullaidh, outside the main northward shell-bay section. It is not part of the Great Estuarine Group. Only the locally relevant upper members are included here; the full Bearreraig succession exposed elsewhere on Skye should not be added beneath the beach log.

Druim An Fhurain Sandstone Member

The southern shore exposes white-weathering sandstone and, towards its top, grey crinoidal limestone. No complete member thickness is established for the inspected Elgol shore exposure. The BGS range of 230–485 m concerns Strathaird at district scale; the older field guide’s 470 m is likewise a member estimate, not the thickness visible on this beach. Older accounts also use the spelling Druim na Fhuarain.

Garantiana Mudstone Member

Small exposures of baked mudstone occur south of the main sill and headland. Older descriptions call this the Garantiana Clay or Garantiana Shales. Neither the older 12 m estimate nor the BGS regional value of up to 18 m measures the visible patches here. The contact with the overlying Cullaidh Shale is not continuously exposed at Elgol.

GREAT ESTUARINE GROUP

The seven formations from Cullaidh Shale to Skudiburgh record repeated changes between low-salinity lagoons, deltaic sand deposition, shell-rich brackish water, episodically emergent lagoon margins and more terrestrial conditions. Marine influence varied through time; no single shell bed or evaporitic feature establishes continuous open-sea deposition. The group may begin in the late Bajocian and most of the local succession is Bathonian. The BGS estimate of 137–139 m in Strathaird is a district-scale total assembled from units, not a continuously measured core-bay column. One exact numerical age should not be applied to the whole walk.

Cullaidh Shale Formation

At the Port na Cullaidh type section, dark organic-rich fissile shale is revealed and concealed by a mobile storm beach. Usually only about 1–2 m is visible, compared with the BGS formation estimate of 4–6 m. Its base is unseen. Thin, irregular basaltic sills interrupt and bake the shale. The original mud accumulated in low-salinity prodelta or lagoonal conditions.

Exposed fossil-bearing shale. Cycloid and ctenoid fish scales occur with sparse gastropods, possible Viviparus and Praemytilus, and rare clam shrimps including Euestheria cf. trotternishensis and Neopolygrapta. The fish name “Leptolepis” is a tentative historical identification, not a secure genus determination for every scale.

Cullaidh–Elgol transition. Upwards, the mudstone becomes progressively silty and the first intensely bioturbated, clay-rich sandstone interbeds mark the transition to Elgol Sandstone. The boundary is gradational rather than an exposed sharp unconformity.

Elgol Sandstone Formation

The local type succession is about 22 m thick in the later field guide, GCR account and BGS framework, superseding an older 15 m estimate. This is the formation thickness, not the height of an individual honeycomb-weathered cliff face. Increasing sand content and coarser sediment record delta advance into shallow water. The formation has no formally named members.

Basal fine sands and shale interbeds. Dark micaceous shale alternates with increasingly thick, bioturbated shaly sandstone. The lower fine sands contain pyrite nodules and a restricted trace-fossil assemblage dominated by Planolites.

Lower and main white sandstone. Fine- to medium-grained, non-calcareous sandstone forms much of the pale cliff, with thin lenticular coarser sand bodies. Its conspicuous honeycomb surface is a weathering pattern in the rock, not fossil coral or a fossil honeycomb.

Rootlet horizon. Rootlets have been recorded approximately 5.5 m above the formation base, indicating colonisation of an emergent or very shallow delta surface. These reported fossil traces are distinct from living lichen on present-day slabs.

Middle inclined sandstone. Medium- to coarse-grained sandstone contains large low-angle inclined surfaces with about 5 m amplitude and corrected palaeodips of 4–7° towards the south-east. Small trough and tabular cross-lamination accompany them. Monocraterion and possible Thalassinoides burrows occur. These are sedimentary structures within the formation, not formal members.

Upper coarse sandstone and bivalve horizon. Coarse and very coarse sand with granules and pebbles contains trough and tabular cross-sets, scours and planar lamination; the upper part includes two trough-cross-stratified cosets. Probable Unio moulds occur in apparent life orientation on dipping top sandstone slabs. The sandstone is generally fossil-poor, so this should not be described as a rich ammonite-bearing unit.

Elgol–Lealt boundary. The overlying Lealt Shale begins at a sharp contact displaced by small faults. A change from pale sandstone to dark shale and repeated shell-bearing limestone bands characterises the approach to the shell-rich bay.

Lealt Shale Formation

This is the principal formation of the shell-rich bay north of Elgol, divided into the lower Kildonnan and upper Lonfearn members. Repeated mud, shell limestone and locally ooidal beds record shallow lagoonal sedimentation with changing salinity, sediment supply and occasional emergence. The BGS figure of about 46 m is for Strathaird. The often-quoted 48 m reference section is at Lealt River in northern Skye and is not an Elgol thickness. Gaps, intrusions and poorly exposed basal beds prevent the following table from supplying a secure independent total for each local member.

Kildonnan Member

The lower member is especially associated with Praemytilus strathairdensis. Its 23 m type-section thickness on Eigg must not be transferred to Elgol. The first two horizons described here lie below the clearly measured interval; Table 1 bed 1 is not the formation base.

Basal fine sandstone below the numbered log. A fine sandstone bed, approximately 0.30 m thick, lies about 1 m above the formation base.

Basal fern-bearing shale below the numbered log. A shale approximately 0.30 m above that sandstone yielded a fusainised fragment of the fern Hausmannia sp., reported as collected by G. Field and identified by C.R. Hill. A discovery year has not been established.

Kildonnan measured beds. The following numbered beds ascend from the bottom of Morton & Hudson’s clearly measured interval. Thin shale partings and separate limestone sub-beds are retained because combining them would lose the source’s bed-level detail.

Bed 1 (1.20 m). Grey fissile shale; Praemytilus in at least the highest 0.20 m, with aligned shells on its top. This is the bottom of the clearly measured interval, not the formation base.

Bed 2 (0.90 m). Grey shale containing small-shell layers.

Bed 3 (0.08 m). Dark limestone with small gastropods, neritids and possible Ptychostylus, plus thin fibrous-calcite veins.

Bed 4 (1.60 m). Grey shale.

Bed 5a (0.15 m). Fine limestone with whole heterodont bivalve valves.

Bed 5b (0.03 m). Coarse shell limestone with iron-rich weathering.

Bed 5c (0.01 m). Shale parting.

Bed 5d (0.06 m). Shell-bearing limestone.

Bed 5e (0.01 m). Shale parting.

Bed 5f (0.06 m). Shell limestone containing pyrite.

Bed 6 (0.12 m). Dark shale.

Bed 7 (0.02 m). Thin shell limestone.

Bed 8 (2.30 m). Dark shale, mostly exposed.

Bed 9a (0.02 m). Dark limestone capped by a small-Neomiodon shell layer.

Bed 9b (0.01 m). Shale parting.

Bed 9c (0.08 m). Dark shell limestone with small bivalves.

Bed 10 (0.45 m). Dark shale deformed by load casts and concretions up to 0.25 m thick; downward-projecting load structures extend into the underlying bed.

Bed 11 (0.13 m). Shell limestone with iron-rich weathering and a load-cast base.

Bed 12a (0.95 m). Grey shale with septarian limestone concretions reaching 0.60 m diameter; irregular limestone veins in upper part are specifically distinguished from calcite veins.

Bed 12b (0.25 m). Regularly bedded dark shale with Modiolus (historical table identification), conchostracans, Darwinula and Unio oblique to bedding, possibly in life position.

Bed 13 (0.20 m). Placunopsis limestone: small bivalves cover bedding surfaces, with Cuspidaria; load-cast base increases local total thickness to 0.30 m. Narrative identifies P. socialis and C. ibbetsoni and interprets a salinity change.

Bed 14 (0.20 m). Domal stromatolite or algal limestone capping the member; gypsum pseudomorphs documented in thin section.

Upper Kildonnan environmental change. The Placunopsis–Cuspidaria shell bed and overlying stromatolitic limestone introduce a change in conditions near the member boundary. Gypsum pseudomorphs indicate evaporitic mineral growth or its replacement, while domal lamination records microbial carbonate construction. These features do not by themselves demonstrate permanently open marine water.

Lonfearn Member

The numbering restarts at 1. Basal Isognomon shell plasters and coquina record a higher-salinity episode, followed by repeated shell limestones, ooidal beds and shales with bivalves, gastropods, ostracods and clam shrimps. The narrative records Skyestheria intermedia among the clam shrimps, but that does not assign the species to every numbered bed. The 30 m type-section thickness at Port Earlish in northern Skye is not an Elgol measurement. Neither ooidal beds nor the basaltic sill constitute an additional formal member.

Bed 1 (0.28 m). Dark shale with possible Neomiodon, large heterodonts, possible Viviparus, fish scales, Cuspidaria, ostracods and indeterminate gastropods.

Bed 2 (0.15 m). Shale with an Isognomon shell plaster.

Bed 3 (0.30 m). Limestone densely packed with Isognomon; shell-laminated coquina at base. Higher-salinity assemblage continues through basal beds 1–3.

Bed 4 (0.48 m). Poorly exposed shale with possible Neomiodon.

Bed 5 (0.20 m). Shell limestone with possible Neomiodon.

Bed 6 (0.40 m). Dark shale with Neomiodon shell plasters, numerous conchostracans and a small mytilid; fibrous calcite at top.

Bed 7 (0.12 m). Shell limestone; fibrous calcite in upper 0.02 m and basal 0.06 m.

Unexposed interval between beds 7 and 8 (0.10 m estimated). Unexposed interval; source gives parenthesised estimated thickness, not a measured rock bed.

Bed 8 (0.60 m). Dark shale with numerous conchostracans and fibrous calcite at top.

Bed 9 (0.50 m). Dark micritic limestone with sparse shell fragments and Viviparus; load-cast base.

Bed 10 (0.16 m). Shell limestone with fibrous calcite.

Bed 11 (1.20 m). Dark shale with rusty weathering, fibrous calcite, conchostracans and fine pyrite. Source notes an agglomerate boulder resting on this bed.

Bed 12 (0.15 m). Grey limestone with shale lamination, fibrous calcite and tiny indeterminate bivalves.

Bed 13 (1.20 m). Dark shale with numerous thin shell limestones, Neomiodon, conchostracans, small indeterminate bivalves and fibrous calcite.

Bed 14 (0.30 m). Shell limestone with Neomiodon; upper 0.20 m has Viviparus or coarse ooids; lower 0.10 m contains fish teeth.

Bed 15 (0.30 m). Shale with fibrous calcite.

Bed 16 (0.10 m). Limestone with Neomiodon and Viviparus.

Bed 17 (0.45 m). Dark shale with fibrous calcite.

Bed 18 (0.05 m). Dark micritic limestone with abundant late pyrite.

Bed 19 (1.00 m). Dark shale with fibrous-calcite bands; strongly disturbed by a dyke.

Bed 20 (0.50 m). Micritic limestone: upper 0.25 m is ooidal with projecting weathered pyrite cubes and Neomiodon; basal 0.25 m is shelly with Neomiodon and Viviparus.

Bed 21 (0.20 m). Dark shale.

Bed 22 (0.12 m). Pale-green micritic limestone, possibly recrystallised.

Bed 23 (0.30 m). Dark shale.

Bed 24 (0.45 m). Ooidal, intraclast-bearing limestone with Viviparus and large indeterminate bivalves seen in section.

Bed 25 (0.45 m). Dark shale with ostracods and Neomiodon shell plasters, strongly baked by the overlying sill.

Basaltic sill between beds 25 and 26 (1.30 m, source value parenthesised). Basaltic sill. Intrusion thickness is excluded from the sedimentary formation thickness.

Bed 26 (thickness unreported). Dark shale with Darwinula, conchostracans and Viviparus. The printed table gives no thickness for this row; the separate sill thickness must not be assigned to this bed.

Bed 27 (0.15 m). Shaly limestone with Neomiodon, bone fragments and phosphatic pebbles; top 0.05 m is coarsely ooidal and intraclast-rich.

Bed 28 (2.00–2.50 m). Shale with a thin shell limestone 0.50 m above base; Neomiodon plasters, ostracods, indeterminate bivalves and possible conchostracans.

Bed 29 (0.58 m). Lower 0.28 m has Neomiodon, fish remains, phosphatic fragments and mudcracked surfaces; upper 0.30 m is shelly ooidal limestone with intraclasts.

Bed 30 (0.15 m). Dark shale.

Bed 31 (0.38 m). Shelly ooidal limestone with possible Neomiodon, shale interbeds and mudcracks.

Bed 32 (0.62 m). Strongly baked dark shale with fibrous calcite and some shell layers containing Darwinula.

Bed 33 (0.12 m). Grey micritic limestone, possibly recrystallised, with a basal fibrous-calcite band.

Bed 34 (0.50 m). Dark shale; Neomiodon plasters towards base, conchostracans and Darwinula towards top.

Bed 35 (0.30 m). Neomiodon shell limestone with abundant ooids and millimetre-scale intraclasts.

Bed 36 (0.10 m). Poorly exposed shale.

Bed 37 (0.10 m). Neomiodon shell limestone.

Bed 38 (2.62 m). Dark shale with Neomiodon, commonly shell plasters or pyritised, plus conchostracans and Unio; thin shell limestones about 0.15 m thick.

Bed 39 (0.50 m). Neomiodon shell limestone with extensive load casting.

Bed 40 (0.40 m). Neomiodon shell limestone; basal half contains shale laminae.

Bed 41 (0.20 m). Dark shale with Neomiodon, some retaining attached ligaments, and conchostracans.

Bed 42 (0.15 m). Neomiodon shell limestone; the upper 0.05 m is more shell-rich.

Bed 43 (0.40 m). Dark shale with Neomiodon shell plasters.

Bed 44 (0.20 m). Grey micritic limestone with fibrous calcite at base and pyritised shells.

Bed 45 (0.30 m). Dark shale with a thin shell limestone, Neomiodon and larger indeterminate bivalves.

Bed 46 (0.15 m). Laminated Neomiodon shell limestone with more micritic levels, intense bioturbation and Planolites burrows several millimetres long.

Bed 47 (0.25 m). Dark shale with Neomiodon shell plasters; highest numbered Lonfearn bed in this measured interval.

Upper Lonfearn and the Valtos transition. Towards the top of the member, shell-rich limestone and shale increasingly show mudcracking, bioturbation and silt input. This anticipates the Valtos facies rather than an abrupt shift to the thick northern-Skye sandstone scenery. Generic fish, bone or phosphatic fragments in this log are not enough to identify a dinosaur, mammal or other particular vertebrate.

Valtos Sandstone Formation

The Elgol and Strathaird succession is relatively thin and unusually carbonate-rich compared with Valtos farther north on Skye. The BGS compilation gives around 21 m in Strathaird, whereas Morton & Hudson regarded the thickness as uncertain and probably no more than 24 m; the GCR account uses approximately 24 m. These estimates should remain qualified rather than being converted into one false exact total. No formal members are recognised here.

Lower Valtos measured beds. The source numbering restarts at 1. These twelve numbered beds and three gaps cover only the lower formation on the northward continuation of the main bay. They are not the separate Glen Scaladal log.

Bed 1 (0.40 m). Neomiodon shell limestone with concretions and intense bioturbation.

Bed 2 (0.90 m). Dark shale with an internal Neomiodon shell-limestone lamina 0.14 m above base; upward increase in silt and abundant Neomiodon, some with valves spread in butterfly position. The printed lamina thickness reads 0.15 cm, so do not silently convert it to metres. This internal lamina value may be a printing error and remains uncertain; the whole bed is recorded as 0.90 m.

Bed 3 (0.35 m). Neomiodon shell limestone.

Unexposed interval between beds 3 and 4 (0.10 m estimated). Unexposed interval, estimated thickness in parentheses.

Bed 4 (0.30 m). Dark shale with Neomiodon plasters and indeterminate valves; base unseen.

Bed 5 (0.40 m). Neomiodon shell limestone with many articulated valves.

Bed 6 (0.20 m). Dark shale with Neomiodon plasters and abundant fish scales.

Bed 7 (0.15 m). Grey micritic limestone with late pyrite and calcite veins.

Unexposed interval between beds 7 and 8 (0.10 m estimated). Unexposed interval, estimated thickness in parentheses.

Bed 8 (0.60 m). Dark shale with possible Neomiodon and a 0.02 m fibrous-calcite band at top; intruded by a felsite dyke, base unseen.

Bed 9 (0.40 m). Micritic limestone with large mudcracks and shale lamination near base.

Unexposed interval between beds 9 and 10 (1.45 m estimated). Gap interpreted as probably shale; estimated thickness, not an observed bed description.

Bed 10 (0.25 m). Neomiodon-rich shell limestone.

Bed 11 (0.20 m). Shale containing fibrous-calcite veins, Neomiodon and larger heterodont bivalves.

Bed 12 (0.50 m). Neomiodon-rich limestone with abundant large Viviparus. Formation continues above; this is not its complete thickness.

Lower Valtos facies beyond the table description. The lower roughly 6 m is described more broadly as sandy carbonates and bioturbated silty fine sands, with laminated calcilutites about 0.05–0.30 m thick. Mudcracks record emergence; Planolites, Lockeia and crustacean burrows up to 3 cm wide record activity in the sediment. The roughly 6 m description overlaps the lower formation and must not simply be added to the numbered table as a new thickness.

Upper northern-bay stack and faulted top. Thin shales are followed by a conspicuous stack of coarsely sandy limestone with basal loading and deformation. A fault cuts out upper Valtos and lower Duntulm in the northern Elgol-bay continuation. The missing beds must not be restored by silently joining this exposure to a different section.

Historical shell-bed terminology. The older term “Cyrena Limestones” was used for parts of the carbonate-rich Valtos succession in Strathaird. Neomiodon and other named bivalves provide more precise descriptions where the specimens are identified; an old “Cyrena” caption alone does not establish a modern species or the source bed of a loose specimen.

Separate Glen Scaladal Valtos section. Beyond the core bay, Valtos is exposed again towards Glen Scaladal. Its base is unseen in this separate section. Sandstones approximately 0.10–0.40 m thick alternate with shales approximately 0.05–0.25 m thick; load casts, detached sandstone masses, Planolites and Neomiodon are recorded. The top 1.3 m is Neomiodon biosparite with abundant Viviparus scoticus. Morton & Hudson’s figure 20 shows two columns with a small but uncertain intervening gap; this is not a proven bed-for-bed continuation of Table 1 bed 12.

Wider-coast succession. From this point, the account concerns the wider Carn Mor–Glen Scaladal coastal sector. The sections are separated by faults, small intrusions, gaps, folding and the Carn Mor landslip. They are geological context for the Elgol guide, not a continuous extension of the main shell-bay measured log or a recommendation to cross unstable ground.

Valtos graphic-log annotations. The two separate columns in the 1995 figure 20 are labelled North Elgol and North Carn Mor. Their printed facies labels are 7, 1 and 5, and 1, 5, 1 and 6 respectively. The figure also carries regional comparison annotations A–E/F of Eigg and F of Muck. These are facies and correlation annotations, not Table 1 bed numbers, additional Elgol members or measured local thicknesses; they do not import the Eigg or Muck successions into this shore section.

Duntulm Formation

Oyster-rich limestone and shale record stronger marine influence within shallow lagoons. The composite north-Elgol/Glen Scaladal reference section contains about 17 m of observed strata plus an unexposed interval of a few metres near its base, superseding the older 8 m estimate. It is not a 17 m uninterrupted exposure at the main shell bay. There are no formal members.

Composite log and numbering. The Andrews & Walton numbering used in Morton & Hudson’s figure 22 is independent of the Lealt–Valtos Table 1 numbering. Beds 1–9 belong to the separate section south of Glen Scaladal; beds 10–48 occur in the main northern-Elgol section, with a gap of a few metres between the lower and main parts of the composite. Beds 10–29 are described chiefly in the cliffs and beds 29–48 on the foreshore. These are source locations, not instructions to approach unstable faces.

What the detailed Duntulm log establishes. The reproduced graphic explicitly labels beds 4, 7, 9, 10, 12, 15, 18, 25, 27, 28, 30, 31, 33, 34, 37, 42, 46 and 48. Bed 29 is the algal interval identified in the accompanying interpretation between 28 and 30. Other divisions are drawn but lack individually recoverable prose descriptions or exact thicknesses in the consulted reproduction. The log also shows an intrusive dyke low in the main section, a sill around beds 38–41 and two further upper exposure gaps. These breaks remain part of the geological account; the drawing does not justify manufacturing a measured thickness for each unlabelled bed.

Oyster limestone, shale and argillaceous limestone facies. Shell-rich limestone and associated shale dominated by Praeexogyra hebridica form the oyster facies. Argillaceous limestone provides a contrasting facies, and nodular or stromatolitic algal limestone a third. The source’s facies labels 1, 2 and 3a describe sediment types, not members of the formation.

Algal beds 7, 27, 29, 31 and 37. An algal horizon is recorded at bed 7 in the basal Glen Scaladal component. The main-section algal horizons are beds 27, 29, 31 and 37, varying in nodular and stromatolitic development; Cayexia nodosa is cited in the algal-facies account. The available reproduction does not support a separate invented thickness or fossil assemblage for each of these five horizons.

Upper transition and final oyster limestone. The top is placed above the last oyster-bearing limestone. About 4 m beneath it already consists largely of argillaceous micritic limestone resembling Kilmaluag lithology, so colour or rock type alone is insufficient to identify the formation boundary.

Kilmaluag Formation

About 25 m is recorded for Strathaird in the BGS framework, compared with 23 m in the older field guide. North Glen Scaladal provides an almost fully exposed partial type section; South Carn Mor exposes a separate middle-to-upper interval. Mudstone, argillaceous limestone, dolomitic beds and repeated desiccation features record low-salinity to freshwater ephemeral lagoons with exposure and drying. Micritic field appearance can partly reflect later baking; the analysed argillaceous limestones contain 7–44% insoluble material. The formation has no formal members, and the names Vertebrate Beds and Breccia Beds are informal.

North Glen Scaladal log: preserved labels and gaps. The reproduced Andrews-numbered North Glen Scaladal log labels 1a, 1e, 1g; 2a, 2c, 2e, 2g, 2l, 2o; 3a, 3c, 3e; 4a, 4c; 6, 7, 8; 9a, 9b1, 9b3, 9c, 9g1, 9h, 9i; 10; 11a–l; 12; 13a, 13b, 13d, 13f, 13h; and 14. Intervening divisions appear in the graphic without individual printed labels. Basal and dyke-related gaps and two sills in the lowermost interval interrupt the succession. This account retains the labelled horizons but does not turn figure dimensions into fabricated bed thicknesses.

South Carn Mor log: a separate correlated section. The separate South Carn Mor column labels 9a, 9b–c, 9e, 9g1–2, 9i, 10 and 11a, and continues upwards into the cliff. Correlation lines connect distinctive horizons to North Glen Scaladal, not every sub-bed. These identifiers belong to the Andrews log; the older Bell & Harris 21-bed Kilmaluag list uses its own numbering and cannot be equated numerically with it.

Lower mudstone–limestone beds. Beds 1–8 and the lowermost part of bed 9, depending on the descriptive grouping, comprise mudstone–limestone alternations with abundant ostracods, desiccation cracks, intraformational mud-clast conglomerates and cryptalgal lamination. A stromatolitic level is recorded within the lower succession. These structures show repeated shallow-water deposition and exposure rather than a single unbroken deep lake.

Vertebrate Beds: principally bed 9 and associated bed 10. The principal bone-bearing interval lies in subdivisions of bed 9, with bed 10 included in older field-guide descriptions of the Vertebrate Beds. Blue-grey, relatively coarse, ostracod-rich limestones contain bone fragments and Viviparus; bases may be irregular, scoured or concretionary. Not every sub-bed is equally bone-rich. The wider Elgol–Carn Mor–Glen Scaladal record includes small vertebrates of exceptional scientific importance, but it is distinct from casual shell finds in the main Lealt bay. Generic bone fragments cannot be assigned to a named animal without specialist study.

Breccia Beds: bed 11a–l. Bed 11a–l forms the Breccia Beds in the reproduced Andrews log. Dolomitic material has cryptalgal lamination, cuboidal clasts and desiccation brecciation, together with vertical pipes or burrows. Older interpretations considered crustacean or crayfish makers and possibly lungfish; subsequent work addressed decapod trace fossils. These structures should not be labelled dinosaur footprints without supporting evidence.

Bed 12: calcrete-bearing mudstone. Mudstone with calcrete nodules records emergence and soil development within the lagoon-margin succession.

Beds 13–14: upper carbonate-rich interval. Carbonate-rich beds return, recording wetter lagoonal conditions before the final change to the Skudiburgh mudstones. The reproduced log distinguishes bed 13a, 13b, 13d, 13f and 13h and the overlying bed 14, without providing a complete individual prose description or secure thickness for every drawn subdivision.

Kilmaluag–Skudiburgh transition and limits of the wider log. The boundary is gradational: upper lagoonal carbonate beds give way to the more terrestrial mudstones of Skudiburgh. There is no evidence here for inserting a sharp marine erosional boundary between the two formations. Detailed descriptions of every unlabelled subdivision of the wider-coast graphic logs were not available in the consulted sources; this limitation does not affect the separately complete main-bay Table 1 account.

Skudiburgh Formation

Purple and green mudstones with calcrete record more terrestrial or alluvial conditions following the Kilmaluag lagoons. The lowest 4 m is well exposed in the wider northern-Elgol sector, while higher beds are poorly exposed. Published district estimates differ, approximately 10–11 m versus 16–18 m, so a complete 18 m beach section should not be claimed. No formal members are recognised.

Upper disconformity. The top is a sharp disconformity beneath the Carn Mor marine sandstone. Thalassinoides burrows descend from the sandstone into the older mudstone, recording colonisation during renewed marine flooding. This surface marks the end of the Great Estuarine Group, not an additional member within it.

Staffin Bay Formation

The formation lies outside the Great Estuarine Group and records the Early Callovian marine transgression. Carn Mor Sandstone is its only local representative in Strathaird. The Ostrea and Belemnite Sands members of northern Skye are absent here and must not be inserted beneath it.

Carn Mor Sandstone Member

The separate reference section farther north exposes about 9 m, while other local accounts describe approximately 10 m. Coarse, locally pebbly, bioturbated marine sandstone overlies the Skudiburgh disconformity. Its age is placed in the Koenigi Zone, Gowerianus Subzone in the inspected field-guide account. The name is Carn Mor, not “Cam Mor”.

Marine fossil-bearing sandstone and upper belemnite horizon. Local nests of the rhynchonellid brachiopod Thurmanella acuticosta occur with rare ammonites recorded as Kepplerites (Gowericeras) gowerianus and Proplanulites koenigi. The upper sandstone contains abundant belemnite moulds, affected by baking and leaching. These marine fossils belong to the wider coast, not automatically to the main Lealt shell bay. Fallen blocks can only be assigned to this member where their lithology and provenance support that identification; “Oxford Clay sandstone” is not an appropriate substitute formation name.

Distant North Elgol Coast: Callovian–Oxfordian context. The following section lies about 2.7–3.6 km north of Elgol and is separate from the main guide’s shell bay. It describes a distant, partly incomplete marine succession, not an uninterrupted column reached by adding thicknesses to the previous sections. Baking associated with the Palaeogene igneous complex affects fossil preservation and sedimentary textures.

Staffin Shale Formation

Despite its name, the local succession includes substantial sandstone and siltstone. Four members are recognised here, all outside the Great Estuarine Group. The GCR figure of 145.5 m concerns the Oxfordian portion of the distant composite section, not the total formation or the village shore. Callovian beds continue beneath the Oxfordian summary and the uppermost exposed member is incomplete. The GCR summary division numbers below are independent of all main-bay and wider Great Estuarine bed numbering.

Tobar Ceann Siltstone Member

An older field guide gives about 19 m for the member in regional Strathaird context. The GCR Oxfordian summary instead divides the portion described into 1a and 1b; underlying Callovian strata continue below and the different thickness scopes must not be conflated.

GCR division 1a (9 m). Approximately 9 m of silty clay and muddy sand with a poor recorded fauna forms the lower Oxfordian summary interval.

GCR division 1b (4 m). Approximately 4 m of sandy silt contains Cucullaea, Pinna and ammonites.

Scaladal Sandstone Member

GCR division 2 (32.6 m). The North Elgol GCR section records 32.6 m of coarse, bioturbated and ripple-drift sandstone. Cardioceras, Perisphinctes and Euaspidoceras occur with marine bivalves. This is GCR summary division 2. Its type section is at Rubha na h-Airigh Baine; separate exposure near the southern Carn Mor landslip is also outside the core shell bay.

Camasunary Sandstone Member

GCR division 3 (91.4 m). About 91.4 m of fine, bioturbated sandstone with rare ammonites is recorded in the distant North Elgol composite section. It is not a sandstone unit at the village shell bay.

Camasunary Siltstone Member

GCR division 4 (up to 7.5 m seen). Up to 7.5 m of blue siltstone is seen, with Amoeboceras, Ringsteadia and marine bivalves. The top is not fully exposed, so this is an observed thickness rather than the complete member total.

Later intrusions and the Elgol vent breccia. Basaltic sills, felsite and other dykes, and the small Elgol vent breccia belong to much later Palaeogene igneous activity. The vent breccia contains fragments of Jurassic sandstone, shale and limestone together with igneous clasts. Intrusions interrupt the sedimentary sections and cause baking, hardening, recrystallisation and changes to pyrite and fossil preservation. Their thicknesses are not Jurassic depositional thickness, and the intrusions are not additional members of the sedimentary formations.

Reading rocks and loose material. Mineral veins, honeycomb weathering, modern lichens and transported beach stones must be distinguished from fossils and in-situ horizons. Burrows, root traces and desiccation cracks are geological evidence when their identification is supported, but a photograph alone does not guarantee the exact structure, formation or numbered bed. A loose block on the beach need not originate from the adjacent exposed bed.

References

Barron, A.J.M., Lott, G.K. & Riding, J.B. (2012). Stratigraphical framework for the Middle Jurassic strata of Great Britain and the adjoining continental shelf. British Geological Survey Research Report RR/11/06, especially sections 8.1–8.3.

Morton, N. & Hudson, J.D. (1995). Field guide to the Jurassic of the Isles of Raasay and Skye, Inner Hebrides, NW Scotland. In Taylor, P.D. (ed.), Field Geology of the British Jurassic, pp. 209–280. Elgol account pp. 237–244; Table 1, pp. 239–240; figures 19–23.

Cox, B.M. (2002). Elgol–Glen Scaladal, Isle of Skye. In Cox, B.M. & Sumbler, M.G., British Middle Jurassic Stratigraphy. Geological Conservation Review Series 26. Includes the later field-guide synthesis and reproduced Valtos, Duntulm and Kilmaluag logs.

Wright, J.K. (2001). North Elgol Coast. In Wright, J.K. & Cox, B.M., British Upper Jurassic Stratigraphy. Geological Conservation Review Series 21, pp. 213–216. Distant Callovian–Oxfordian section.

Bell, B.R. & Harris, J.W. (1986). The Strathaird Peninsula, Skye: an excursion. Historical field-guide account hosted by BGS Earthwise; older terminology, thicknesses and independently numbered logs require the qualifications given above.

British Geological Survey Lexicon. Elgol Sandstone Formation, code ESA.