Kettleness Fossil Hunting

1822–1828 – Young and Bird established the Yorkshire coast succession that includes Kettleness
One of the earliest major scientific milestones for Kettleness came with the classic work of Young and Bird on the Yorkshire Jurassic coast. Their studies helped establish the fossil-rich Lower Jurassic succession of this stretch of coast in the geological literature and laid the foundations for later work on the ammonites, ironstones and reptile-bearing beds of the Kettleness area.

1829 – John Phillips published the classic early account of the Yorkshire Lower Jurassic
Phillips’ work provided one of the key early frameworks for the Lower Jurassic of the Yorkshire coast, including the succession represented around Kettleness. This became one of the main starting points for later stratigraphic and palaeontological work on the area.

1876 – Tate and Blake published sections that underpinned later work on the Kettleness succession
The studies of Tate and Blake became the basis for much of the later geological understanding of the Upper Pliensbachian and Lower Toarcian beds along this part of the coast. Kettleness forms part of that classic research stretch between Staithes and Port Mulgrave.

1883 – a plesiosaur skeleton was found at Kettleness
Kettleness produced a notable plesiosaur discovery in 1883. This is one of the clearest dated fossil finds tied to the locality and helped build the site’s long reputation for marine reptile remains.

1892 – Fox-Strangways reviewed the classic early work on the coast
By the late nineteenth century, the geology and fossil-bearing beds of the Staithes–Kettleness–Port Mulgrave coast had become important enough to be synthesised in Geological Survey work. This helped cement the scientific importance of the locality within the Yorkshire Jurassic succession.

1933 – Arkell highlighted the significance of the Yorkshire Lower Jurassic coast
Arkell’s work kept the Kettleness coast central to discussions of the British Lower Jurassic. By this time the area was already well known for its fossiliferous ironstones, ammonites and marine reptile remains.

1955 – Howarth produced the stratigraphic framework later used for the Kettleness beds
Howarth’s detailed work on the Yorkshire Lower Jurassic provided the framework for the beds exposed around Kettleness, including the Cleveland Ironstone succession and adjacent shales. His work underpinned much of the later modern interpretation of the coast.

1992 – Rawson and Wright reinforced the importance of the Staithes to Port Mulgrave coast
Modern synthesis work treated the coast that includes Kettleness as one of the best British sections through the Upper Pliensbachian to Lower Toarcian succession. This confirmed the scientific importance of the locality not only for fossil collecting, but also for Jurassic stratigraphy.

1990s – Kettleness was recognised as part of the type section for major Jurassic formations
Modern Geological Conservation Review work confirmed the wider coast from Staithes to Port Mulgrave, including Kettleness, as the type section for the Staithes Sandstone Formation, the Cleveland Ironstone Formation and the Penny Nab Member. This gave the locality a direct place in the formal framework of British Jurassic geology.

Modern era – one of the largest and most complete Yorkshire pliosaur skeletons was discovered at Kettleness
Kettleness is now especially noted as the source of the largest and most complete “Rhomaleosaurus” pliosaur skeleton found from the Yorkshire coast, now displayed in the Natural History Museum’s marine reptile gallery. This is one of the best-known vertebrate discoveries associated with the site.

Modern understanding – Kettleness remains one of Yorkshire’s most productive localities for reptile remains
Today Kettleness is widely recognised as one of the most productive fossil localities in Yorkshire for reptile remains, while also being well known for ammonites from the Cleveland Ironstone and associated beds. Its importance lies in combining strong collecting potential with major stratigraphic significance on the classic Staithes to Port Mulgrave coast.

Section Architecture

Kettleness is not a single clean vertical cliff log. The lower part of the succession is best understood from foreshore reefs south and south-east of the point, including Lingrow Knock and adjacent platforms, whereas the higher Whitby Mudstone succession was historically exposed in the old alum quarries and in the modified upper cliff. Nineteenth-century alum and jet working, later cliff recession and repeated landslip have drastically altered the natural profile, so the locality must be treated honestly as a composite of foreshore, slip debris and old quarry faces rather than as one uninterrupted modern section.

Numbering Note

Formal published bed numbers exist for parts of the Kettleness succession, especially in Howarth’s classic Yorkshire Pliensbachian and Grey Shale studies, but the modern exposure is too altered to present every bed as a simple field log. The breakdown below therefore uses formal members and named horizons throughout, retaining published bed references where they are securely tied to Kettleness or to the standard Yorkshire coastal Lower Jurassic scheme used to correlate this coast.

LIAS GROUP

Cleveland Ironstone Formation (Upper Pliensbachian)

Kettleness Member

Bed KB1 — Lingrow Knock Reef And Upper Kettleness Member Ironstones

The low foreshore reefs at Kettleness expose the upper part of the Cleveland Ironstone Formation, the member that now formally bears the locality name. The detached reef of Lingrow Knock is classically formed largely by the upper ironstone of the Ironstone Series, and the broader upper Kettleness Member includes the Pecten and Main Seam interval together with intervening sandy, micaceous mudstones and shales. Lithology is highly cyclical: grey to brown shales and sandy mudstones coarsen upward into sideritic to berthierine-rich oolitic ironstones with irregular burrowed tops, shell concentrations and local rolled fossil accumulations. Typical Fossils: abundant bivalves in some shell beds, with characteristic upper Spinatum-Zone ammonites including Pleuroceras of the paucicostatum, apyrenum, elaboratum and hawskerense groups; rarer associates in the upper Kettleness Member include Amauroceras ferrugineum, A. lenticulare and very rare immigrant hildoceratids. Stratigraphic Significance: this is the classic uppermost Cleveland Ironstone, lying above a minor but regionally important non-sequence that separates the Kettleness Member from the underlying Penny Nab Member. Depositional Environment: storm-influenced lower-shoreface to offshore marine cycles, each capped by ironstone formed during major breaks in clastic sedimentation and repeated shallow-water reworking.

Bed KB2 — Upper Boundary Beds And Sulphur Band

Near the top of the upper Pliensbachian transition at Kettleness lies the famous Sulphur Band, a thin, finely laminated shale with abundant jet lenticles and much pyrite, which weathers to a characteristic yellow sulphurous surface. At Kettleness this was recognized by Howarth as a discrete bed within the uppermost ironstone succession. It is overlain by grey to dark-grey shales with calcareous concretions and shelly pockets, including Pseudopecten equivalvis, Pholadomya and locally Lytoceras. The horizon is historically important because it played a major role in discussion of the base of the Toarcian, although the lowest unequivocal typical Toarcian ammonites occur slightly higher in the overlying Grey Shale succession. Interpretation: abrupt deepening and reduction in benthic activity at the close of Cleveland Ironstone sedimentation, with pyrite-rich lamination and early organic concentration foreshadowing the more offshore Grey Shale and later bituminous Mulgrave facies.

Whitby Mudstone Formation (Lower Toarcian; Basal Boundary Beds At Kettleness Include The Latest Pliensbachian Transition)

Grey Shale Member

Bed KB3 — Basal Grey Shale Member, Howarth Beds 1–3 (c. 1.1 m In The Standard Yorkshire Scheme)

The basal Grey Shale Member begins immediately above the top of the ironstone succession and is exposed on the Kettleness foreshore in low, less resistant shale reefs. The lowest beds are grey to dark grey shales, the basal part still latest Pliensbachian in ammonite character, followed by the first indisputably Toarcian level. In the standard Yorkshire scheme, Bed 3 yields the earliest typical Toarcian fauna of the district, including Protogrammoceras paltum and Dactylioceras sp. Lithology: shaly mudstone, less coarse and less ferruginous than the Cleveland Ironstone below, with scattered small nodules and a stronger offshore aspect. Interpretation: the onset of the Grey Shale marine mud regime above the ironstone cycles, recording deeper and quieter offshore deposition during the Pliensbachian–Toarcian transition.

Bed KB4 — Lower Grey Shale Member, Paltus And Clevelandicum Intervals (Howarth Beds 4–19; c. 4.4 m)

This lower grey-shale package consists of grey shales with multiple bands of calcareous and sideritic concretions. Beds of the Paltus interval contain some belemnites and bivalves in a generally mud-dominated facies, while the overlying Clevelandicum interval yields more abundant dactylioceratids. Typical Fossils: Dactylioceras of the paltum, crosbeyi and clevelandicum groups, together with belemnites and scattered bivalves. Locally, concretions weather red and stand out clearly from the shale. Stratigraphic Significance: this interval forms part of the classic Yorkshire reference section for the lower Tenuicostatum Zone and is one of the reasons Kettleness is so important in early Toarcian ammonite correlation. Depositional Environment: offshore mud accumulation under generally oxygenated to mildly stressed conditions, quieter and more basinward than the upper Cleveland Ironstone below.

Bed KB5 — Upper Grey Shale Member, Tenuicostatum And Semicelatum Intervals (Howarth Beds 20–32; c. 8.1 m, Giving A Grey Shale Member Thickness Of About 13.5 m Overall)

The upper Grey Shale Member continues in grey shales and shaly mudstones with several bands of small nodules, then several conspicuous bands of larger pyritic calcareous concretions. This is one of the most ammonite-rich parts of the Kettleness foreshore. Typical Fossils: common and often well-preserved Dactylioceras tenuicostatum in small nodules, followed higher by D. semicelatum, large belemnites and the nautiloid Cenoceras astacoides; the uppermost bed contains shell bands rich in crushed Tiltoniceras antiquum, with Posidonia radiata also present. Stratigraphic Significance: this interval carries the standard Yorkshire Tenuicostatum and Semicelatum subzones and has long been central to lower Toarcian ammonite zonation. Interpretation: quiet offshore shelf mud deposition, but with a progressive shift upward into more restricted and partly bituminous facies, presaging the oxygen-stressed black-shale conditions of the Mulgrave Shale Member above.

Mulgrave Shale Member

Bed KB6 — Jet Rock, Equivalent To The Lower Mulgrave Shale Member (Howarth Beds 33–40; c. 7.2 m In The Standard Yorkshire Section)

The Jet Rock is the classic lower bituminous division of the Mulgrave Shale Member and is represented at Kettleness on the foreshore, in fallen nodules and historically in old workings. It consists of dark grey to black bituminous and pyritic mudstone with enormous calcareous concretions, including the Cannon Ball Doggers, Whalestones, Curling Stones, Top Jet Dogger limestone and Millstones. The lower third of the member is the principal jet-bearing interval, formed from highly compressed fossil wood. Typical Fossils: Elegantuliceras elegantulum, Cleviceras exaratum, C. elegans, Harpoceras serpentinum, Hildaites murleyi, Dactylioceras spp. and Phylloceras heterophyllum, together with abundant belemnites. Interpretation: laminated, organic-rich offshore mud deposited under strongly oxygen-restricted to anoxic bottom conditions during the early Toarcian environmental crisis; this is one of the most distinctive black-shale facies in the British Jurassic.

Bed KB7 — Upper Mulgrave Shale Member: Bituminous Shales And Ovatum Bed

Above the Jet Rock the member continues in dark bituminous shale with scattered rows of pyritic or sideritic concretions and local shell-rich levels. The shale is still organic-rich and dark, but generally less dominated by giant concretionary horizons than the Jet Rock below. The top is marked by the Ovatum Bed, a double row of large sideritic concretions and pyritic masses that forms one of the key markers in the upper Mulgrave. Typical Fossils: Harpoceras of the falciferum group, including forms historically referred to H. mulgravium, Dactylioceras spp., Nodicoeloceras incrassatum and Ovaticeras ovatum; belemnites include Youngibelus tubularis, Y. simpsoni, Simpsonibelus dorsalis and species of Acrocoelites. Dense belemnite concentrations or “battlefields” are typical at some levels. Interpretation: continuation of the lower Toarcian black-shale regime under persistently dysoxic to anoxic conditions, with the Ovatum Bed marking the top of the most strongly bituminous facies.

Alum Shale Member

Bed KB8 — Hard Shales, Lower Alum Shale Member

The Hard Shales form the lower part of the Alum Shale Member and are composed of grey non-bituminous shales with scattered calcareous nodules and pyritic masses. Compared with the Mulgrave Member below they are less richly bituminous, less perfectly laminated and more hospitable to benthic and nektonic faunas, though still deposited in quiet offshore waters. Typical Fossils: Dactylioceras commune, D. temperatum and Hildoceras of the lusitanicum group, with belemnites and subordinate bivalves. Interpretation: the first stage of recovery from the peak black-shale facies below, with less severe bottom-water restriction but continued fine-grained offshore sedimentation.

Bed KB9 — Main Alum Shales

The Main Alum Shales are softer, less calcareous and generally paler-weathering than the Hard Shales or Cement Shales, and they formed the principal raw material for the alum industry that transformed the Kettleness cliffs into their present man-modified profile. These shales are grey when fresh but weather pale grey, buff and yellow in the quarry faces. Typical Fossils: Dactylioceras commune and D. athleticum, Frechiella subcarinata, Pseudolioceras lythense, Peronoceras fibulatum, P. turriculatum, P. subarmatum and Hildoceras of the bifrons group, with common Nuculana ovum, Gresslya, belemnites and large driftwood logs. Vertebrates: much of the classic Kettleness marine reptile material is traditionally attributed to the lower Bifrons-Zone “communis” levels within the Main Alum Shales and the transition into the Cement Shales. Interpretation: offshore mud deposition under improving but still fluctuating oxygenation, with the shale chemistry suitable for alum extraction because of its relatively low calcium carbonate content.

Bed KB10 — Cement Shales And Upper Alum Workings

The Cement Shales form the harder and more calcareous upper part of the Alum Shale Member. They contain abundant beds and rows of calcareous concretions, many formerly burnt for Roman cement, and they are more resistant than the softer Main Alum shales beneath. Typical Fossils: Hildoceras of the bifrons group, Porpoceras of the vortex group, Catacoeloceras crassum, belemnites and abundant Nuculana ovum. Vertebrates: plesiosaurs and other marine reptiles are historically especially common in the Main Alum and Cement Shales at Kettleness, and at least some classic specimens are thought to have come from the Cement Shales or from the uppermost Main Alum–lowest Cement interval. Interpretation: continued offshore marine mud deposition with stronger concretion growth, increasing calcareous content and repeated pauses in sedimentation, before the younger Toarcian succession was cut out by the overlying Dogger erosion surface.

Dogger Formation (Aalenian)

Bed KB11 — Dogger Unconformity And Ferruginous Cap, Where Preserved

Where the natural upper contact survives, the Whitby Mudstone is cut by a sharp erosional unconformity beneath the Dogger Formation. The Dogger is a ferruginous sandstone or ironstone of highly variable thickness and lithology, and on this part of the coast it commonly rests directly on the Alum Shale Member because the higher Toarcian Peak Mudstone and Fox Cliff Siltstone members are absent. At Kettleness much of this upper contact has been altered, removed or obscured by old quarrying and subsequent cliff retreat, but the regional stratigraphic meaning is clear: a major break and reworking surface at the base of the Middle Jurassic succession.

Exposure And Preservation Note

Kettleness is one of those Yorkshire localities where the industrial and geological histories are inseparable. The upper cliffs are partly artificial quarry faces cut into the Alum Shale Member, the original headland has been greatly reduced by extraction and landslip, and much fossil material is now recovered from fallen nodules, slip debris and foreshore blocks rather than from an intact in-situ face. The page therefore emphasizes securely recognizable horizons and member-level packages rather than pretending that every historic fossil can still be tied to a neat modern exposure.

Depositional Environment

The Kettleness succession records a major shift from the uppermost late Pliensbachian ironstone shelf into the lower Toarcian mudrock basin of the Cleveland Basin. The Kettleness Member of the Cleveland Ironstone Formation was laid down as storm-influenced marine mud and silt cycles capped by berthierine- and siderite-rich ironstones formed during prolonged pauses in clastic sedimentation and repeated shallow-water reworking. The Grey Shale Member records renewed deepening and quieter offshore mud accumulation during the Pliensbachian–Toarcian transition. The Mulgrave Shale Member then represents the famous lower Toarcian organic-rich black-shale facies, deposited under strongly oxygen-restricted bottom waters during the Toarcian Oceanic Anoxic Event, with giant concretions and horizons of compressed fossil wood that formed jet. The Alum Shale Member records a gradual return to less strongly restricted offshore conditions, though still within a quiet muddy sea, with Hard Shales, softer Main Alum Shales and more calcareous Cement Shales marking a long recovery interval before erosion and condensation at the base of the Dogger Formation.

Total Thickness Note

The exact modern thickness visible at Kettleness cannot be measured as one clean section because quarrying and landslip have destroyed the original continuous face. What can be stated securely is that the Grey Shale Member alone is about 13.5 m thick in the classical Yorkshire scheme, and Kettleness also exposes the overlying Mulgrave and Alum Shale members through many additional tens of metres up to the Dogger unconformity, together with the uppermost few metres of the Kettleness Member below.

References

Howarth, M.K. (1955). The ammonite zones of the uppermost part of the Middle Lias 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.
Cox, B.M., Sumbler, M.G. & Ivimey-Cook, H.C. (1999). A formational framework for the Lower Jurassic of England and Wales.
Page, K.N. (2004). Staithes to Port Mulgrave and Boulby Quarries, in British Lower Jurassic Stratigraphy, Geological Conservation Review Series 30.
British Geological Survey Lexicon of Named Rock Units: Cleveland Ironstone Formation, Kettleness Member, Grey Shale Member, Mulgrave Shale Member, Alum Shale Member and Dogger Formation.
Jarvis, I. and co-authors (2024) on the upper Pliensbachian–middle Toarcian chemostratigraphy of the Cleveland Basin and the Toarcian Oceanic Anoxic Event.
Benton, M.J. & Taylor, M.A. (1984), Benton, M.J. & Spencer, P.S. (1995), and Vincent, P. & Smith, A.S. (2009) on the Kettleness marine reptile material and its source horizons.
English Heritage / RCHME survey reports on the Kettleness alum works for the historic modification of the cliff section.