Staithes Fossil Hunting

1822–1828 – Young and Bird used the terms “Staithes Beds” and “Kettleness Beds” and figured fossils from the succession
One of the earliest major scientific milestones for Staithes came with the work of Young and Bird, who used the terms “Staithes Beds” and “Kettleness Beds” for the lower and upper parts of the Upper Pliensbachian succession and illustrated fossils from these beds. This helped establish Staithes as an important Yorkshire Jurassic locality.

1829 – John Phillips published a detailed section and long fossil list for Staithes
Phillips provided a detailed section for the Upper Pliensbachian at Staithes, dividing it into a lower “Marlstone Series” and an upper “Ironstone Series”, together with a substantial fossil list. This was one of the key early descriptions of the locality and helped fix Staithes in the geological literature.

1876 – Tate and Blake published sections that became the basis for most later work
The sections published by Tate and Blake were so important that later reviews treated them as the foundation for most subsequent study of the Staithes succession. Their work helped refine understanding of the fossiliferous beds and their stratigraphic relationships.

1878–1886 – Wright added further detailed work on the Staithes succession
Wright continued the detailed study of the Staithes section, adding further important observations on the fossil-bearing beds. Together with the earlier nineteenth-century work, this strengthened Staithes’ reputation as one of the classic Lower Jurassic coastal sections in Britain.

1892 – Fox-Strangways reviewed the early work on the Staithes coast
By the late nineteenth century, the accumulated geological work at Staithes had become important enough to warrant synthesis and review. Fox-Strangways brought together the results of the earlier studies and helped cement the significance of the locality.

1920 – large-scale extraction of the Main Seam showed the industrial importance of the Cleveland Ironstone at Staithes
Staithes and the coast towards Port Mulgrave were historically important for ironstone mining. By 1920, millions of tonnes had been extracted from the Main Seam in Cleveland, underlining the huge industrial as well as geological importance of the fossil-bearing succession exposed here.

1933 – Arkell reviewed the classic early studies and highlighted the significance of the section
Arkell’s work helped keep Staithes central to discussions of the Yorkshire Lower Jurassic. By this point the coast was already recognised as one of the classic British sections for this part of the Jurassic, both for its fossils and its stratigraphy.

1955 – Howarth produced the stratigraphic framework that later workers continued to use
Howarth’s detailed sections became the standard framework for most later work on the Staithes succession. His bed numbering and stratigraphic treatment underpinned much of the modern interpretation of the Staithes Sandstone, Cleveland Ironstone and adjacent beds.

1985 – Howard revised the lithostratigraphy of the Upper Pliensbachian sequence
Modern lithostratigraphic revision refined the understanding of the fossiliferous Upper Pliensbachian succession at Staithes. This helped place the classic beds into a clearer modern framework and improved correlation across the Cleveland Basin.

1995 – Rawson and Wright published detailed modern logs of the Staithes Sandstone, Cleveland Ironstone and Whitby Mudstone formations
Detailed logged sections published in the 1990s helped bring together the classic nineteenth- and twentieth-century work into a modern stratigraphic framework. This confirmed the continued importance of Staithes as one of the key Lower Jurassic reference sections in Britain.

Modern understanding – Staithes is recognised as the type section for major Jurassic formations and one of Britain’s key Lower Jurassic reference localities
Today the cliffs and foreshore between Staithes and Port Mulgrave are recognised as the type site for the Staithes Sandstone Formation, the Cleveland Ironstone Formation and the Penny Nab Member, and as one of the best British exposures of the Upper Pliensbachian to Lower Toarcian succession. The coast remains important for ammonites, belemnites, bivalves, trace fossils and occasional vertebrate remains.

Section Architecture

The succession dips gently eastward, so the oldest beds are exposed at Cowbar Nab and around Staithes harbour, with progressively younger beds passing eastward across Penny Nab, Jet Wyke, Old Nab and Brackenberry Wyke to Port Mulgrave. Only a few minor faults interrupt the sequence, but they locally repeat ironstone seams on the foreshore, and fallen Middle Jurassic Saltwick Formation blocks obscure parts of Brackenberry Wyke and the Sheep Stones area; the higher Toarcian cliff section above Port Mulgrave is present but not cleanly accessible as a foreshore log.

Numbering Note

The upper Pliensbachian beds of the Staithes Sandstone and Cleveland Ironstone formations retain the formal bed numbers of Howarth (1955), whereas the Whitby Mudstone beds retain the later Howarth (1962, 1973) numbering and therefore restart at Bed 1 above the Sulphur Band. That reset is preserved here rather than simplified, because it is the published Yorkshire scheme used for detailed correlation.

LIAS GROUP

Redcar Mudstone Formation (Lower Jurassic: Lower Pliensbachian)

Ironstone Shale Member

Bed ST1 — Upper Ironstone Shale Member Below The Oyster Bed (Maculatum Subzone; c. 20.25 m)

At Cowbar Nab the highest exposed Redcar Mudstone Formation consists of grey mudstone with some siltstone in the upper part, calcareous nodules at several levels, and a thin oolitic ironstone about 1.5 m above the base of the exposed interval. The succession remains dominantly muddy and offshore in character, but becomes slightly siltier upward toward the Staithes Sandstone above. Androgynoceras maculatum var. rigida has been recorded from this interval. Interpretation: offshore shelf mud deposition below the incoming storm-dominated sandy facies of the Staithes Sandstone Formation.

Staithes Sandstone Formation (Lower Jurassic: Lower To Middle Pliensbachian)

Bed ST2 — Oyster Bed (0.30 m)

A ferruginous, calcareous shell bed packed with Gryphaea gigantea, Oxytoma and Pseudopecten equivalvis, forming the formal base of the Staithes Sandstone Formation and the base of the Capricornus Subzone. The bed is persistent across the Cleveland Basin and marks the first fully sandstone-dominated phase above the muddier Ironstone Shale Member. Interpretation: a shell-rich storm or transgressive lag at the base of a shallower, more energetic shelf-sand succession.

Bed ST3 — Lower Staithes Sandstone, Howarth (1955) Beds 1–3 (Capricornus Subzone; 2.7 m)

Sandstone forms the base of the cliff at Cowbar Nab, passing up into sandy shale capped by a band of calcareous concretions. This interval records the initial establishment of the classic Staithes storm-sand facies. Rare ammonites include forms referred to Androgynoceras lataecosta, and the bed tops are typically burrowed, showing that storm-laid sands were followed by quieter intervals of seabed colonization.

Bed ST4 — Main Lower Sandstone Package, Howarth (1955) Beds 4–9 (Figulinum Subzone; 6.55 m)

Mainly sandstone alternating with sandy shale, with bivalve-rich shell beds near the top and Gryphaea lower down. Oistoceras has been recorded from Beds 4 and 8. The beds are classically cyclic, each unit having a sharp erosive base with local shelly lag, overlain by sand showing planar lamination, ripple lamination and locally hummocky cross-stratification, before being bioturbated upward into muddier tops. Interpretation: repeated storm-event deposition on a shallow shelf, followed by fair-weather reworking and benthic colonization.

Bed ST5 — Upper Figulinum Package, Howarth (1955) Beds 10–11 (2.0 m)

Bed 10 is a shale with scattered calcareous concretions, including abundant Oistoceras figulinum in its upper part and O. cf. affligulinum nearer the middle, while Bed 11 is a thin sandstone with bivalve shell beds. Together they form a distinct upper Figulinum Subzone package that records a quieter muddy interval followed by a final shell-rich sandy pulse before the more persistently sandy upper Staithes section.

Bed ST6 — Middle To Upper Sandstone Cycles, Howarth (1955) Beds 12–17 (part) (Stokesi Subzone; 8.5 m)

Thinly bedded sandstones with some sandy shale and bands of calcareous concretions and lenticles, many weathering red and some rich in bivalves. Amaltheus stokesi occurs sporadically, and the base of Bed 12 is a parastratotype for the base of the Stokesi Subzone. This is the coarsest part of the formation: poorly bioturbated fine-sandstone units up to about 4 m thick show planar and cross-lamination, hummocky cross-stratification, gutter casts and small erosional channels. One hummocky unit yielded abundant intact but poorly preserved Balanocrinus gracilis. Interpretation: storm-dominated inner- to middle-shelf sands with increasingly energetic event deposition.

Bed ST7 — Upper Shell-Bearing Sandstones, Howarth (1955) Beds 17 (part)–22 (5.5 m)

Thinly bedded sandstones with thin shales and bands of calcareous, sometimes fossiliferous, concretions. A thin shell bed at the base yields Amaltheus stokesi and A. wertheri. Higher in the package, shell concentrations and coquinas of Protocardia truncata occur, with current-aligned belemnites, fragments of driftwood, and muddy bed tops burrowed by bivalves and the long tube-like fossil traditionally called Dentalium giganteum. Interpretation: waning-stage tempestites and fair-weather muddy tops on a shallow marine shelf.

Bed ST8 — Uppermost Staithes Sandstone, Howarth (1955) Bed 23 (1.95 m)

Shale and sandstone with three bands of calcareous concretions, the middle band containing Amaltheus stokesi and A. wertheri. This is the topmost bed package of the Staithes Sandstone Formation at Staithes, fining and becoming more shaly before the first row of scattered siderite nodules that marks the base of the Cleveland Ironstone Formation. Interpretation: the final, still storm-influenced shelf-sand cycle before renewed mud accumulation and ironstone-capped cyclicity.

Total Thickness Of Staithes Sandstone Formation At The Type Coast Near Staithes: Approximately 28.6 Metres

Cleveland Ironstone Formation (Lower Jurassic: Upper Pliensbachian)

Penny Nab Member

Penny Nab Member Note

The Penny Nab Member comprises four principal ironstone-capped cycles — the Osmotherley, Avicula, Raisdale and Two Foot seams — separated by shale, siltstone and fine sandstone. Except beneath the Two Foot Seam, each clastic unit generally coarsens upward from silty pyritic shale to argillaceous fine sandstone and is capped by an erosive ironstone bed with reworked or bio-eroded siderite nodules.

Bed ST9 — Basal Cleveland Ironstone Transition, Howarth (1955) Beds 24–25 (2.6 m)

Shale with bands of calcareous concretions, the lowest containing abundant Amaltheus stokesi and A. wertheri. Howard placed the base of the Cleveland Ironstone Formation at the first row of scattered siderite nodules within this transition, so these beds record the actual shift from sandstone-dominated Staithes shelf sedimentation into mudrock-and-ironstone cyclicity. Interpretation: deeper and muddier shelf conditions than the Staithes Sandstone below, but still strongly affected by repeated shoaling and storm reworking.

Bed ST10 — Osmotherley Seam, Howarth (1955) Bed 26 (0.08 m)

A very thin but persistent oolitic ironstone or sideritic concretion band containing Amaltheus subnodosus, A. striatus, A. stokesi and many bivalves. The base of Bed 26 is a parastratotype for the base of the Subnodosus Subzone. Interpretation: condensed ironstone cap formed at the top of the first Penny Nab cycle during reduced clastic supply and shallow marine reworking.

Bed ST11 — Inter-Osmotherley Clastics, Howarth (1955) Beds 27–30 (6.5 m)

Silty sandstone, siltstone and shale with bands of calcareous concretions and a shell bed about 0.58 m below the top, containing Protocardia truncata, Entolium and other bivalves. Amaltheus subnodosus, A. striatus and A. margaritatus occur at several levels, especially in the lowest nodule band of Bed 27a, which yielded the neotype of A. subnodosus. Interpretation: a full coarsening-upward lower-shoreface to shallow-shelf cycle with storm concentration of shells and later nodule growth.

Bed ST12 — Avicula Seam, Howarth (1955) Bed 31 (0.6 m)

A fine-grained ironstone with pale green chamositic ooids and, in places, a mudstone parting about 0.1 m thick around the middle. It is characterized by abundant Oxytoma cygnipes and protocardiid burrows. On the foreshore minor faults locally repeat the seam, and fresh surfaces show the ooidal and sideritic fabric particularly well. Interpretation: a burrowed, erosively based ironstone cap produced during renewed sediment starvation and shallow-water reworking.

Bed ST13 — Inter-Avicula To Raisdale Clastics, Howarth (1955) Beds 32–34 (5.0 m)

Siltstone and shale with pyritic masses in the lower part and a band of calcareous concretions about 1.25 m above the base yielding Amaltheus gibbosus; Amauroceras ferrugineum occurs in the shale above. Beneath the Raisdale Seam this interval includes the classic “upper striped bed”, a set of thin laminated siltstones that fine upward into dark mudstone, each with a basal erosion surface and commonly east–west gutter casts. Interpretation: storm-influenced interseam sedimentation with repeated waning-upward event beds and a return to quieter muddy conditions before the next ironstone cap.

Bed ST14 — Raisdale Seam, Howarth (1955) Bed 35 (0.25 m)

A thin ironstone seam rich in Protocardia truncata and with rarer Amaltheus cf. margaritatus. Despite its small thickness it is a clear field marker and records another shallow, reworked shell-rich ironstone phase at the top of a shoaling cycle.

Bed ST15 — Inter-Raisdale To Two Foot Clastics, Howarth (1955) Beds 36–38 (2.9 m)

Shale with a band of calcareous concretions about 1.1 m above the base and a belemnite-rich band near the top. The concretions yield Amaltheus gibbosus, A. margaritatus, Pseudoamaltheus engelhardti and Amauroceras ferrugineum. Compared with the underlying interseam package, this interval is muddier and more pelagic in aspect, but still shoals upward toward the next ironstone seam.

Bed ST16 — Two Foot Seam And Top Shale, Howarth (1955) Beds 39–40 (0.9 m)

The Two Foot Seam is a 0.4 m ironstone with rare Amaltheus ex gr. margaritatus and Pseudoamaltheus engelhardti, overlain by 0.5 m of shale with crushed Amaltheus gibbosus. This uppermost Penny Nab interval is unusual because the clastic unit beneath the seam lacks the clear upward-coarsening displayed beneath the other Penny Nab ironstones, suggesting that transgression curtailed clastic supply before a full shoaling cycle could develop.

Total Thickness Of Penny Nab Member At The Type Coast: Approximately 18.8 Metres

Kettleness Member

Kettleness Member Note

The Kettleness Member is separated from the Penny Nab Member by a regional non-sequence that is markedly unconformable in parts of the basin. At Staithes the basal break lies at the base of the Pecten Seam, the lower Spinatum transiens and salebrosum zonules are absent, and the member is dominated by the Pecten and Main seams together with a thin unnamed upper ironstone near the top of the Spinatum Zone.

Bed ST17 — Basal Kettleness Transition And Pecten Seam Package, Howarth (1955) Bed 41 And Beds 42–50 (c. 1.55 m)

Bed 41 is a ferruginous shale with a basal bivalve shell bed, immediately overlain by the Pecten Seam, an ironstone package in five thin beds separated by silty shale partings and containing shell-rich levels. Howard placed the member base at the minor erosion surface at the base of the seam itself, where phosphatic pebbles may occur. Pseudopecten equivalvis is especially characteristic, and the brachiopod Rhynchonelloidea lineata is recorded from near the base of the Pecten Seam. Interpretation: a condensed, repeatedly reworked shallow-marine ironstone package deposited after a significant break in sedimentation.

Bed ST18 — Main Seam Lower Package, Howarth (1955) Beds 51–53 (c. 2.15 m)

Bed 51 is a hard black shale representing a brief muddy break above the Pecten Seam. Above it, Beds 52–53 form the thick bottom block of the Main Seam, about 1.7 m of ironstone separated from the top block by shale. Burrows are present, but rolled fossil concentrations are much less common than in the top block, and ammonites are uncommon and difficult to extract, though Pleuroceras paucicostatum is probable. Interpretation: the principal mined ironstone body of the Staithes coast, recording a major condensed and partly bioturbated ironstone phase.

Bed ST19 — Main Seam Top Block, Howarth (1955) Bed 54 (0.75 m)

An ironstone with branching burrows and concentrations of rolled fossils, famous at Old Nab where marine erosion has exposed stall floors riddled with Rhizocorallium preserving scratch marks made by crustaceans; Chondrites is common on intervening pillars. The ammonite fauna includes Pleuroceras paucicostatum, P. elaboratum, P. apyrenum, Amauroceras ferrugineum and A. lenticulare, with a uniquely British Tethyan hildoceratid record of Canavaria aff. cultraroi. Small phosphate clasts are common. Interpretation: a highly condensed, heavily reworked ironstone cap with strong firmground colonization and fossil-lag concentration.

Bed ST20 — Top Kettleness Beds, Howarth (1955) Beds 55–57 (1.90 m)

Bed 55 is a shale with Pleuroceras hawskerense; Bed 56 is a thin ironstone with an irregular top surface containing common P. hawskerense and very rare Protogrammoceras turgidulum; Bed 57 is a sandy, micaceous shale also containing P. hawskerense. These beds close the Cleveland Ironstone Formation and yield the highest unequivocally Pliensbachian ammonite recognized at Staithes. Interpretation: renewed clastic input above the Main Seam followed by a final thin ironstone and topmost muddy-sandy shelf sedimentation immediately before the abrupt facies jump into the Whitby Mudstone.

Total Thickness Of Kettleness Member At Staithes: Approximately 6.35 Metres

Total Thickness Of Cleveland Ironstone Formation At The Type Coast Near Staithes: Approximately 25.2 Metres

Whitby Mudstone Formation (Lower Jurassic: Pliensbachian–Toarcian Boundary Beds To Lower Toarcian In This Section)

Grey Shale Member

Whitby Mudstone Boundary Note

At Staithes and Port Mulgrave the base of the Whitby Mudstone Formation is taken at the base of the Sulphur Band. This lithostratigraphical boundary does not coincide neatly with the chronostratigraphical Pliensbachian–Toarcian boundary, because the highest unequivocally Pliensbachian ammonite is Pleuroceras hawskerense in Bed 57 below, while the lowest definite typical Toarcian fauna occurs only at Grey Shale Bed 3 higher in the succession.

Bed ST21 — Sulphur Band, Howarth (1955) Bed 58 (0.20 m)

A finely laminated pyritic mudstone with numerous lenticles of jet, forming the formal base of the Whitby Mudstone Formation on this coast. The change from the sandy micaceous top of the Cleveland Ironstone below to this dark sulphur-weathering laminae is abrupt and is one of the sharpest facies breaks in the Yorkshire Lower Jurassic. Interpretation: onset of a transgressive, much more restricted muddy regime and a precursor to the fully organic-rich facies higher in the lower Toarcian.

Bed ST22 — Boundary Shales, Howarth (1955) Beds 59–60 And Howarth (1973) Beds 1–3 (c. 1.57 m)

The numbering resets above the Sulphur Band. Beds 59–60 are shales with a row of calcareous concretions at the top, yielding Pseudopecten equivalvis and Pholadomya. Above them, Grey Shale Beds 1–3 are grey to dark-grey shales, Bed 2 being laminated and bituminous; Bed 3 yields the lowest typical Toarcian fauna elsewhere in the district, including Protogrammoceras paltum and indeterminate Dactylioceras. Together these beds form the critical boundary interval between the last Pleuroceras-bearing Spinatum facies and the first classic Toarcian dactylioceratid shales.

Bed ST23 — Lower Grey Shale Concretion Package, Howarth (1973) Beds 4–17 (2.75 m)

Grey shales with six bands of calcareous and sideritic concretions, with some belemnites and bivalves. These beds belong to the Paltus Subzone and form the lower part of the classic Grey Shale foreshore at Brackenberry Wyke and Port Mulgrave. Interpretation: quiet offshore mud deposition, still normal enough to support limited benthos, with repeated early cementation into nodule bands.

Bed ST24 — Crosbeyi And Clevelandicum Interval, Howarth (1973) Bed 18 And Beds 19a–c (1.65 m)

Bed 18 is grey shale with small calcareous concretions and frequent Dactylioceras crosbeyi; it forms the crosbeyi Biohorizon and the base of Bed 18 is a parastratotype for the base of the Clevelandicum Subzone. Bed 19a is laminated and bituminous, Bed 19b contains red-weathering lenticles and common D. clevelandicum, and Bed 19c returns to grey shale. This short package shows the increasing development of restricted, partly bituminous facies in the upper Grey Shale.

Bed ST25 — Dactylioceras tenuicostatum Interval, Howarth (1973) Beds 20–27 (2.75 m)

Grey shale with several bands of small calcareous nodules and a double band of large calcified lenticular masses, weathering red, near the base. Common well-preserved Dactylioceras tenuicostatum occurs in the nodules, and the neotype of the species came from Bed 22. The base of Bed 20 is a parastratotype for the base of the Tenuicostatum Subzone. This is the classic D. tenuicostatum horizon of the Staithes–Port Mulgrave coast and one of the most important lower Toarcian ammonite levels in Yorkshire.

Bed ST26 — Dactylioceras semicelatum Interval, Howarth (1973) Beds 28–31 (3.55 m)

Grey shale with three bands of large calcareous concretions, including a double row at the base; the concretions are commonly pyritic and yield well-preserved Dactylioceras semicelatum, large belemnites and a nautiloid Cenoceras. The base of Bed 28 is a parastratotype for the base of the Semicelatum Subzone. This is one of the most fossiliferous parts of the Grey Shale foreshore and is especially noted for red-weathering nodule rows that can be followed laterally.

Bed ST27 — Upper Grey Shale Shell-Bed, Howarth (1973) Bed 32 (1.85 m)

Grey shale with occasional flat calcareous nodules and widespread shell beds, especially near the base, packed with crushed Tiltoniceras antiquum; Dactylioceras semicelatum and Posidonia radiata are also present. The shell-pavement character makes this a conspicuous top-Grey Shale marker just below the dark Mulgrave Shale facies. Interpretation: an offshore mudstone punctuated by shell concentrations and local winnowing immediately before the onset of the more strongly restricted Jet Rock facies.

Total Thickness Of The Sulphur Band, Boundary Shales And Grey Shale Beds Logged Here: Approximately 14.3 Metres, Of Which Grey Shale Beds 1–32 Account For About 13.7 Metres

Mulgrave Shale Member

Mulgrave Shale Member Note

Port Mulgrave is the type locality of the Mulgrave Shale Member. The foreshore and lower cliff chiefly expose the lower part of the member — the Jet Rock and the lowest Bituminous Shales — while the higher part continues upward into the cliff; hard jet occurs mainly in the upper 3 m of the Jet Rock and more brittle soft jet higher in the Bituminous Shales.

Bed ST28 — Cannon Ball Doggers And Lower Jet Rock Shale, Howarth (1973) Beds 33–34 (2.85 m)

Bed 33 is the Cannon Ball Doggers, a basal row of spherical calcareous concretions up to about 0.18 m in diameter, rich in well-preserved Elegantuliceras elegantulum. Above them, Bed 34 is grey bituminous shale with frequent calcareous concretions and more Elegantuliceras elegantulum. Together these beds form the base of the Mulgrave Shale Member at its type locality and mark the first fully organic-rich Jet Rock facies, laid down under markedly oxygen-restricted bottom-water conditions.

Bed ST29 — Whalestones, Howarth (1973) Bed 35 (0.90 m)

Large ovoid calcareous concretions up to about 3 m long and 1 m thick, with many smaller concretions including the Lower Pseudovertebrae, set in grey bituminous shale. Cleviceras exaratum is common, with less frequent Harpoceras serpentinum and Phylloceras heterophyllum. The Whalestones form one of the classic Port Mulgrave foreshore horizons and record massive early concretion growth within laminated organic-rich mud.

Bed ST30 — Exaratum–Elegans Jet Rock Package, Howarth (1973) Beds 36–38 (2.92 m)

Bed 36 is grey bituminous shale with Cleviceras exaratum. Bed 37 is the Curling Stones horizon, calcareous concretions with pyritic skins and a spheroidal shape up to about 0.45 m in diameter, containing Cleviceras elegans, Harpoceras serpentinum, Dactylioceras semiannulatum, D. crassoides and Phylloceras heterophyllum. Bed 38 returns to grey bituminous shale with occasional concretions and the Upper Pseudovertebrae about 0.3 m above its base. This package is one of the clearest expressions of the lower Toarcian anoxic facies on the Yorkshire coast.

Bed ST31 — Top Jet Dogger And Millstones, Howarth (1973) Beds 39–40 (0.53 m)

Bed 39, the Top Jet Dogger, is a continuous band of argillaceous limestone and formed the roof bed for many old jet workings; despite its field name it is not the Middle Jurassic Dogger Formation. Bed 40 comprises the Millstones, giant lenticular calcareous concretions up to about 4.5 m across when seen from above, with Cleviceras elegans, Hildaites murleyi and Dactylioceras. These are among the most spectacular concretionary beds at Port Mulgrave and close the main Jet Rock interval.

Bed ST32 — Lower Bituminous Shales, Howarth (1973) Bed 41 (5.9 m)

Grey bituminous shale with crushed Harpoceras ex gr. falciferum, probably including H. mulgravium, seen above the Millstones on the shore east of Port Mulgrave and in the cliff. The base of Bed 41 is effectively a parastratotype for the base of the Falciferum Subzone. Calcareous concretions, some pyrite-skinned, are common; flattened ammonites are frequent, and the fauna also includes the pelagic bivalves Pseudomytiloides dubius and Bositra radiata. The almost complete absence of benthic fauna is a key sign of reducing bottom conditions, and rare vertebrate remains, including a partial Steneosaurus, have been recorded from the upper Jet Rock–lower Bituminous Shales part of the section.

Higher Continuation Note

Higher Bituminous Shales and the Alum Shale Member continue above the core foreshore section in the Port Mulgrave cliffs, but they are not cleanly loggable from the shore in the way that the Staithes Sandstone, Cleveland Ironstone, Grey Shale and lower Mulgrave are. The detailed bed-by-bed page therefore stops at the lowest Bituminous Shales and does not force an artificial cliff log for the inaccessible upper cliff succession.

Total Thickness Of The Mulgrave Shale Member Actually Logged Here: About 13.1 Metres Of Lower Jet Rock And Lower Bituminous Shales, Within A Full Port Mulgrave Type Thickness Of About 31 Metres

Depositional Environment

The Staithes succession records a long-term environmental swing across the middle and late Pliensbachian into the early Toarcian. The upper Ironstone Shale Member represents offshore muddy shelf sedimentation. The Staithes Sandstone Formation records repeated storm-laid sand sheets and tempestites on a shallow shelf, with erosive channel-floor lags, planar and hummocky cross-stratification, ripple lamination and strongly bioturbated muddy tops. The Cleveland Ironstone Formation represents a shallower storm-influenced lower-shoreface to shelf setting organized into coarsening-upward cycles capped by erosive berthierine- and siderite-rich ironstones formed during pauses in clastic sedimentation and repeated reworking. The abrupt jump into the Sulphur Band and Grey Shale records transgression and renewed muddy deposition, while the Mulgrave Shale Member marks the development of strongly oxygen-restricted to anoxic offshore conditions during the early Toarcian, with laminated bituminous mudstone, giant concretion horizons, jet formation from compressed driftwood, abundant ammonites and very sparse benthos.

Total Thickness Covered Here: Approximately 101 Metres Of Lower Jurassic Stratigraphy From The Upper Ironstone Shale Member Through The Lower Bituminous Shales Of The Mulgrave Shale Member Across The Composite Staithes–Port Mulgrave Section

References

Howarth, M.K. (1955). Domerian of the Yorkshire coast.
Howarth, M.K. (1962). The Jet Rock Series and the Alum Shale Series of the Yorkshire coast.
Howarth, M.K. (1973). The stratigraphy and ammonite fauna of the Upper Liassic Grey Shales of the Yorkshire coast.
Howarth, M.K. (1992). The Ammonite Family Hildoceratidae in the Lower Jurassic of Britain.
Howard, A.S. (1985). Lithostratigraphy of the Staithes Sandstone and Cleveland Ironstone formations (Lower Jurassic) of north-east Yorkshire.
Hesselbo, S.P. & Jenkyns, H.C. (1995) on the remeasured Staithes–Port Mulgrave section and sequence stratigraphy of the Cleveland Basin.
Rawson, P.F. & Wright, J.K. (1995). The Yorkshire Coast, with detailed logs for Staithes to Port Mulgrave.
Simms, M.J., Chidlaw, N., Morton, N. & Page, K.N. (2004). Geological Conservation Review account for Staithes to Port Mulgrave in British Lower Jurassic Stratigraphy.
British Geological Survey Lexicon of Named Rock Units: Redcar Mudstone Formation, Staithes Sandstone Formation, Cleveland Ironstone Formation, Whitby Mudstone Formation, Grey Shale Member and Mulgrave Shale Member.
Greensmith, J.T., Knox, R.W.O’B., Catt, J.A., Young, B., Macquaker, J.H.S. & Taylor, K.G. on the sedimentology, storm structures, ironstone petrology and cyclicity of the Staithes Sandstone and Cleveland Ironstone formations.