Speeton Cliffs Fossil Hunting

1829 – John Phillips published one of the earliest major accounts of the Speeton succession
John Phillips’ early work helped establish Speeton as an important Yorkshire coastal section. This was one of the starting points for the long scientific history of the Speeton Clay and its fossils.

1858–1859 – Leckenby gave one of the first specific geological accounts of the Speeton Clay
Mid nineteenth-century work by Leckenby helped fix Speeton as a distinct Lower Cretaceous clay succession of major interest. These early descriptions laid the groundwork for the much more detailed fossil and stratigraphic studies that followed.

1868 – Judd divided the Speeton Clay using its ammonite faunas
Judd’s work was one of the first major attempts to subdivide the Speeton Clay using ammonites. This was an important scientific milestone because it tied the succession directly to fossil faunas rather than just lithology.

1889 – Lamplugh introduced the famous lettered subdivisions of the Speeton Clay
George William Lamplugh reorganised the Speeton succession into the lettered beds that became standard in later work. His subdivision of the clay into units such as the A, B, C and D Beds became the classic framework for understanding the site.

1892 – Pavlow and Lamplugh linked the Speeton Clay to wider European successions
Late nineteenth-century work by Pavlow and Lamplugh helped show how the Speeton Clay related to equivalent Lower Cretaceous beds elsewhere in Europe. This greatly increased the international importance of the site.

1924 – Spath published important work on the ammonites of the Speeton Clay
L. F. Spath’s study of the ammonites was one of the classic fossil milestones for Speeton. His work helped refine the age and subdivision of the succession and confirmed the importance of Speeton for Lower Cretaceous ammonite biostratigraphy.

1960 – Neale refined the subdivision of the Upper D Beds
J. W. Neale’s work brought much greater detail to one part of the Speeton Clay succession, helping clarify the fossil-bearing beds and their stratigraphic relationships. This was one of the key twentieth-century refinements of the classic Speeton framework.

1983 – Rawson and Mutterlose further improved the Lower Cretaceous biostratigraphy of Speeton
Later twentieth-century work continued to refine the age and fossil zonation of the Speeton Clay, confirming the cliffs as one of the most important Lower Cretaceous reference sections in Britain.

2001 – the Speeton plesiosaur was discovered near Speeton
A nearly complete Lower Cretaceous plesiosaur, missing only the head, was discovered near Speeton in 2001 by amateur collector Nigel Armstrong. Because Lower Cretaceous plesiosaurs are rare, this became one of the most important modern vertebrate finds from the locality.

1958 and 1985 – key Speeton ichthyosaur specimens were collected
Important ichthyosaur material was collected from the Speeton Clay in 1958 and again in 1985. These specimens later became central to the recognition of one of Speeton’s most important named marine reptiles.

2012 – Acamptonectes densus was formally described from Speeton material
The ichthyosaur specimens collected from the Speeton Clay were formally described in 2012 as Acamptonectes densus. This made Speeton one of the key British localities for Early Cretaceous ichthyosaurs and showed that important marine reptile discoveries were still emerging from old collections.

Modern understanding – Speeton Cliffs remain one of Britain’s most important Lower Cretaceous fossil sites
Today Speeton is recognised as the classic reference section for the Speeton Clay Formation and one of the most important exposed marine Lower Cretaceous successions in Britain. The cliffs are especially known for ammonites, belemnites, crustaceans such as Meyeria ornata, fish remains, sharks and marine reptiles.

Speeton must be treated honestly as a composite coastal section. Most of the cliff is commonly obscured by slumped Quaternary till, and the solid beds appear in different sectors: the Kimmeridge Clay and basal Speeton Clay near New Closes Cliff, the C Beds around Middle Cliff, the B Beds around Black Cliff, the A Beds in temporary slip-bounded slices east of Speeton Beck, and the Red Chalk and lowest Chalk near Buckton and Red Cliff Hole. Within the Speeton Clay Formation the British Geological Survey does not currently use a formal member framework at outcrop, so the classic published A–E bed divisions and their formal sub-bed notations are retained here where useful.

Kimmeridge Clay Formation (Upper Jurassic, Context Interval)

Bed F — Upper Kimmeridge Clay Substrate

The Speeton Clay rests unconformably on the uppermost exposed Kimmeridge Clay, seen intermittently beneath the till and on the foreshore near New Closes Cliff. These are black pyritic shales and paper shales with large dolomitic concretions, yielding flattened ammonites such as Pectinitites pectinatus; nearby beach exposures have also produced higher Kimmeridgian faunas referable to the hudlestoni and wheatleyensis intervals. This Jurassic substrate matters because it shows that the Portlandian and Purbeck successions of southern England are absent here, and that the base of the Cretaceous at Speeton is a major erosional break.

Speeton Clay Formation (Upper Berriasian To Middle Albian At Outcrop)

The classic A–D divisions are fundamentally belemnite-based and remain the practical framework for the section: the D Beds are characterised by Acroteuthis lateralis and allies, the C Beds by Hibolites jaculoides, the B Beds by oxyteuthid belemnites such as Praeoxyteuthis, Anlacoteuthis and Oxyteuthis, and the A Beds by Neohibolites. Lithologically, the formation is made up of mudstones, cementstones, phosphatic and glauconitic horizons, and sporadic bentonites, recording a long offshore marine history with repeated pauses in sedimentation and local erosion on the sea floor.

Bed E — Coprolite Bed (c. 0.1 m)

The basal Cretaceous bed is the famous Coprolite Bed, a thin but persistent phosphatic nodule lag resting sharply on the eroded Kimmeridge Clay. It consists of rolled and fragmentary phosphatic and pyritised bivalves, ammonites and vertebrate debris and represents the slow accumulation of reworked sea-floor sweepings on a major omission surface. There is a marked break at its base and a less obvious one at its top. This bed was once mined for phosphate, and it remains the clearest marker of the Jurassic–Cretaceous break at Speeton.

Beds D7–D6 — Lower D Beds, Including The Blue Bed / Stone Band Interval

The lowermost D Beds comprise black, blue and brown clays with pyrite, glauconite and local selenite, and they include the Blue Bed and the hard pale Stone Band within the D6 interval. Alternating striped pale and dark clays are characteristic, and several thin yellow-weathering bentonite horizons represent altered volcanic ash falls. The fauna is Boreal in flavour, with robust square-sectioned belemnites of the Acroteuthis group. These beds belong mainly to the Berriasian part of the succession and represent quiet offshore mud deposition punctuated by condensation and ash falls.

Beds D5–D4 — Ligula Bed And Astarte Bed Interval

Higher in the D Beds, the dark-brown Ligula Bed and the shelly Astarte Bed provide two of the best named marker horizons in the lower Speeton Clay. The lithology is still dominantly brown to grey marine clay, but shelly interbeds become more obvious, and the Astarte Bed records one of the clearer benthic shell concentrations in the early part of the section. These beds are important in field correlation because they break up what would otherwise be a rather monotonous clay succession.

Beds D3–D1 — Upper D Beds, Including The Exogyra Band, Remanié Horizon And Compound Nodular Bed (uppermost D Beds c. 14.21 m total for the whole D interval)

The upper D Beds include more nodular and phosphatic levels, an Exogyra-bearing band in the D3 interval, the dark and glauconitic remanié horizon in Bed D2, and the fossiliferous Compound Nodular Bed at the top, Bed D1. The latter is a distinctive series of isolated nodules showing more than one phase of nodule growth, an excellent sign of very slow accumulation and early sea-floor lithification. Ammonites, bivalves, brachiopods and crustaceans occur, and large plesiosaur bones have been found in the higher D Beds. This upper part of the D succession spans the Valanginian into the basal Hauterivian and becomes increasingly condensed upward.

Beds C11–C7 — Lower C Beds / Endemoceras Beds

The Lower C Beds begin above the D1 nodular hardground and include pale and dark clays with nodules, among them the Green Clay at C11A and several large-ammonite-bearing brown silty clays around C7. Ammonites of the Endemoceras group dominate the lower Hauterivian part of the succession, with uncoiled heteromorphs such as Aegocrioceras and Crioceratites also important. Brown phosphatic nodules and local glauconite remain common, and the alternation of pale and dark clay indicates continuing rhythmic sedimentation in an offshore marine setting. This lower C interval is especially valuable biostratigraphically because it ties the Speeton section closely to north German Boreal Hauterivian successions.

Beds C6–C4 — Middle C Beds, Including The Main Speetonensis Bed (C6)

The middle C Beds are lithologically varied, with dark and olive-grey clays, brown-weathering limestone and nodule bands, glauconitic seams and locally pyritic dark shaly clays. Bed C6 is the Main Speetonensis Bed, a key ammonite horizon, and the interval above includes several brown-weathering limestone bands and dark glauconitic clays that make the middle C Beds easier to recognise than many parts of the section below and above. Shark and ray teeth are known from hiatal horizons in the Hauterivian part of the section, and some phosphatic nodules have yielded the classic “Speeton shrimp”, Meyeria ornata. These beds still represent open-marine clay deposition, but with repeated minor pauses, shell concentrations and early diagenetic nodule formation.

Beds C3–C1 — Upper C Beds, Including The Echinospatangus Bed (C3) And Transition To The Lower B Beds

The upper C Beds include the Echinospatangus Bed at C3 and higher dark and pale clay alternations leading up to the base of the Lower B Beds. By this stage the ammonite fauna has shifted upward into the Simbirskites-rich part of the Hauterivian succession, and the section is one of the key European reference intervals for the Simbirskites beds. Echinoids, bivalves and belemnites accompany the ammonites, while phosphatic and calcareous nodules remain common. The whole C Beds are about 39.02 m thick and form the great expanded Hauterivian core of the Speeton Clay.

Lower B Beds — LB6 To LB1 (c. 20.94 m)

The Lower B Beds crop out at Black Cliff and are mainly dark blue-grey clays with intercalations of paler clay, common pyrite and local glauconite. The lowest part still contains the topmost Hauterivian, but most of the interval is Barremian. Large fragmentary ammonites, bivalves, gastropods and a rare echinoid occur with the oxyteuthid belemnite fauna, and the section becomes increasingly rhythmic upward. In the upper part of the Lower B Beds, especially the LB1 and LB2 intervals, small-scale sedimentary cycles are developed and laminated shales locally become so dark and finely layered that they have been compared with the German Blätterton facies. These beds are among the best indications at Speeton of repeated short-term environmental oscillations within a generally offshore basin mudstone setting.

Cement Beds — Middle B Beds (c. 9.75 m)

The Cement Beds form one of the most distinctive practical divisions of the Speeton Clay. Black pyritic clays contain seven bands of large impure limestone nodules, of which the lowest three are the most persistent. These nodules have roughly the right proportions of clay and carbonate to have been worked historically as Roman cement, and they were extensively quarried and mined in the 19th century. Fossils occur, but collector interest is often more in the lithology and industrial history than in abundance of shells. Depositional conditions remained marine and offshore, with repeated nodule-forming pauses and early cementation within otherwise soft mud.

Upper B Beds — Uppermost Barremian To Basal Aptian (about 9.4 m, but commonly incompletely exposed)

The Upper B Beds are very pyritic clays with some browner beds, usually poorly exposed because they lie in the most landslip-prone part of the coastal section. Laminated black shales dominate and are rich in pyrite nodules; belemnites are abundant, especially oxyteuthids, and small uncoiled ammonites occur. The upper Barremian part passes upward toward the Aptian, but the exact continuity is difficult to demonstrate because exposures are fragmentary and commonly faulted or slipped. This is one of the intervals where Speeton most clearly shows why the locality cannot be forced into a simple single-face measured log.

Lower A Beds — Basal Aptian Sand Bed, Hard Black Marls And Ewaldi Marl

The base of the Aptian is rarely seen, but where exposed it begins with a brown sandy bed with large concretions and common part-phosphatised Prodeshayesites, one of the very few distinctly quartz-sandy horizons in the entire Speeton succession. Above this lie hard black marls with pyrite and phosphate nodules, then the pale tough Ewaldi Marl with common Neohibolites ewaldi, crushed inoceramids, terebratulids and occasional ammonites. A strongly burrowed surface with a lenticular pebble bed of reworked phosphate pebbles and broken belemnites marks the base of the Ewaldi Marl. The higher Aptian at Speeton has yielded ammonites of the fissicostatus, forbesi and deshayesi zones, and the incoming of the Ewaldi Marl facies marks the base of the forbesi Zone. These beds show that the transition out of the Barremian black-shale regime involved renewed condensation, burrowing and local sand influx rather than simple uninterrupted mud accumulation.

Greensand Streak — Major Glauconitic And Phosphatic Condensation Surface

The Greensand Streak is the most conspicuous and field-useful bed in the A Beds. It is a black-green clay rich in glauconite and small black phosphate pebbles, resting on a significant erosion surface and forming a natural slip plane in the cliff. Older authors numbered it differently in different schemes, but all agreed on its significance. Poorly fossiliferous silty shales of the Albian tardefurcata Zone lie below it, and the glauconite- and phosphate-rich bed is interpreted as marking the base of the mammillatum Superzone. The actual Aptian–Albian boundary has not been observed directly at Speeton, and the Greensand Streak therefore marks one of the clearest condensed intervals in the upper Speeton Clay rather than a simple chronostratigraphic bed boundary.

Upper A Beds — Lower To Middle Albian Minimus Marl Interval (whole A Beds c. 12 m)

Above the Greensand Streak lie grey-brown to red-brown calcareous clays with green-grey patches, pinkish bands, common burrowing and local discontinuous limestone bands. The lower part carries abundant small blunt-ended Neohibolites of the minimus group, rich microfaunas and, in sieved samples, shark teeth; baryte-coated phosphates occur in several beds. The uppermost A Beds become more burrowed and inoceramid- and terebratulid-bearing, and rare bedding surfaces rich in crushed hoplitid or hamitid ammonites have been recorded. This interval represents lower and part of the middle Albian at Speeton, and its sharp but rarely seen passage into the overlying Red Chalk marks the first clear approach of the chalk sea to the Cleveland Basin margin.

Total Thickness Of Speeton Clay Formation At Speeton Cliffs: About 100–105 Metres At Outcrop

Hunstanton Formation (Red Chalk) (Middle Albian To Earliest Cenomanian)

At Speeton the Hunstanton Formation is vastly thicker and more complex than the thin Red Chalk of Norfolk. It forms an expanded, bedded red marl and limestone succession about 24 m thick in the coastal reference section and up to about 30 m in the wider Cleveland Basin. At this locality the formal member names proposed for the Yorkshire coast are worth using because they describe real lithological changes and can be traced in the cliff and foreshore.

Queens Rock Member

Beds QR1–QR7 — Queens Rock Member (c. 4.95 m)

The basal member of the Hunstanton Formation rests sharply on the A Beds and is composed of red marly limestone with occasional seams of pale limestone nodules. At Speeton it includes tough streaky marls with greenish streaks, flattened pale nodules marked by dark red burrows, numerous small nodules and lenses of inoceramid debris, and a conspicuous pale nodular limestone higher in the member. An erosion surface divides the member into two parts. The overall appearance is still marl-dominated rather than fully nodular chalk, and it records the first step from glauconitic Albian clay into ferruginous chalky marl deposition. Belemnites and inoceramid debris are characteristic, but fossils are commonly hard to extract.

Speeton Beck Member

Beds SB1–SB19 — Speeton Beck Member (c. 3.49 m)

This member consists of rhythmically bedded white and pink limestones with grey or red marls and calcareous clays. At Speeton it includes alternating red or greyish marls and paler nodular limestones, dark rubbly limestones, and hard marls with paler nodules in which inoceramid fragments may be common. The argillaceous beds redden upward and the limestones become harder and more nodular. These beds are important because they contain many of the ammonite-bearing units once mistakenly assigned to the uppermost Speeton Clay. The member records repeated fluctuations in carbonate versus marl input during continued marine condensation on the basin margin.

Dulcey Dock Member

Beds DD1–DD22 — Dulcey Dock Member (c. 6.7 m)

The Dulcey Dock Member is a thicker, strongly nodular red limestone unit and one of the most distinctive parts of the Speeton Red Chalk. Alternating dark marls and nodular limestones, several double pale limestone bands with erosion surfaces, and darker marl seams rich in small shells occur through the member. The Inoceramus lissa-rich horizons, Biplicatoria hunstantonensis-rich horizons and the so-called breccia nodule bed are especially important markers. This is a condensed open-marine chalk–marl succession with repeated early lithification and local reworking on the sea floor.

Weather Castle Member

Beds WC1–WC7 — Weather Castle Member (c. 2.81 m)

The Weather Castle Member comprises brick-red marls and marly limestones in a series of rather ill-defined rhythms, capped by a thick red marl. At Speeton the member weathers into massive hard marls with softer bands and is less obviously nodular than the Dulcey Dock limestones below. Aucellina occurs throughout and provides one of the clearest palaeontological signatures of the unit. The Albian–Cenomanian boundary lies near the top of the expanded Hunstanton Formation at Speeton, and the Weather Castle Member is therefore critical to understanding that transition in the Cleveland Basin.

Red Cliff Hole Member

Beds RCH1–RCH5 — Red Cliff Hole Member (c. 5.6 m)

The highest Hunstanton member at Speeton is composed of dark red and grey strongly nodular limestones. The lower part is commonly belemnite-rich; upward, hard flaser-bedded limestones with thin marl seams dominate, and some beds weather or alter to pale white or greenish nodular limestone. Distinctive pale limestone bands with burrowed erosive tops and vertical burrows form excellent field markers. Aucellina and brachiopods are common through much of the member. This unit is earliest Cenomanian in age and forms the bridge between the classic Red Chalk facies below and the white basal Ferriby Chalk above.

Total Thickness Of Hunstanton Formation At Speeton Cliffs: About 24 Metres Exposed, Expanding To Roughly 30 Metres In The Cleveland Basin

CHALK GROUP

Ferriby Chalk Formation (Lower Cenomanian, Context Interval)

Bed FC1 — Crowe’s Shoot Member / Basal Ferriby Chalk

The base of the Ferriby Chalk at Speeton is taken at an erosion surface above the Hunstanton Formation and is represented in the Cleveland Basin by the flaser-bedded white chalks with red or purple marls of the Crowe’s Shoot Member. At the base and in the lowest exposed part, flaser-bedded pale chalks with irregular marl seams pass upward into harder pale limestones with burrows, and inoceramid-fragmental chalk occurs higher in the accessible section. This bed-set shows the decisive lithological change from red ferruginous chalk-marl sedimentation into the buff-weathering grey-white flint-free Chalk proper. Regionally the Ferriby Chalk is 33–35 m thick on the coast at Speeton, but only its basal part is directly relevant to the classic Speeton Cliffs Lower Cretaceous page.

Depositional Environment

The Speeton succession records a long history of marine deposition in the Cleveland Basin and adjacent North Sea Basin margin. The lower Speeton Clay accumulated as offshore mud under generally quiet water, with repeated episodes of very slow sedimentation shown by phosphatic nodules, reworked lags and omission surfaces; the D Beds include bentonites from volcanic ash falls, the C Beds record a richly ammonite-bearing Hauterivian sea, and the B Beds include pyritic black shales, cyclic laminated intervals and cementstone formation. In the A Beds, brief sandy incursions, the burrowed Ewaldi Marl, the glauconitic Greensand Streak and micaceous Albian shales show renewed condensation and transgressive surfaces. The Hunstanton Formation marks the gradual shift into ferruginous chalky marl and nodular limestone deposition in an increasingly chalk-dominated sea, and the Ferriby Chalk records the full arrival of the Northern Province Chalk sea.

Structural Style And Exposure

Speeton Cliffs are geologically famous but deceptively awkward. The solid Mesozoic section has a gentle regional southerly dip so that younger beds appear southward, yet the actual outcrops are broken by landslips, beach cover, minor folding, local faulting and cryogenic or glacitectonic disturbance. The A Beds and uppermost B Beds are especially notorious for appearing only in small slip-bounded slices along the base of the cliff east of Speeton Beck, while the lower part of the formation may be folded beneath Quaternary deposits. Any stratigraphic page for Speeton therefore has to combine multiple locality windows rather than pretend that one neat continuous cliff face exists.

Stratigraphic Significance

Speeton Cliffs are of international importance because they expose an almost complete marine Lower Cretaceous succession from the upper Berriasian to the middle Albian, followed by an unusually expanded Red Chalk and the basal Cenomanian Chalk. The section is the type section of the Speeton Clay Formation and a key reference for Boreal Lower Cretaceous ammonite and belemnite biostratigraphy. It is also critical for understanding mid-Cretaceous condensation, onlap onto structural highs, the Albian–Cenomanian transition in north-east England, and the correlation of onshore Yorkshire strata with the offshore North Sea basin fill.

Typical Fossils

Typical fossils from the Speeton Cliffs succession include ammonites such as Endemoceras, Aegocrioceras, Crioceratites, Simbirskites, Prodeshayesites and later hoplitids and hamitids; belemnites including Acroteuthis, Hibolites, Praeoxyteuthis, Anlacoteuthis, Oxyteuthis and Neohibolites; bivalves such as Astarte, Exogyra, Inoceramus and Aucellina; brachiopods; echinoids such as Echinospatangus; the decapod Meyeria ornata; shark and ray teeth from sieved Albian and Hauterivian horizons; and occasional marine reptile remains, especially in the higher D Beds. Collector success varies greatly with exposure, because many of the most fossiliferous beds are visible only after cliff falls or winter stripping of beach cover.

Total Thickness Covered Here

The bedrock succession relevant to the classic Speeton Cliffs page includes the topmost Kimmeridge Clay substrate, about 100–105 m of Speeton Clay Formation, about 24 m of Hunstanton Formation at outcrop, and the basal part of a Ferriby Chalk Formation that is about 33–35 m thick on the Speeton coast. In practical field terms, however, the locality is best understood not as one single measured 160 m face, but as a composite lower Cretaceous to basal Cenomanian coastal transect assembled from several shifting cliff and foreshore exposures.

References

Phillips, J. (1829). Illustrations of the Geology of Yorkshire.
Lamplugh, G.W. (1889, 1896, 1924) on the subdivision and review of the Speeton Clay.
Judd, J.W. (1868, 1870) on the Speeton Clay and its northern European correlations.
Kaye, P. (1964). Observations on the Speeton Clay.
Neale, J.W. (1960, 1962, 1968, 1974) on the upper D Beds, Lower D ammonites and litho- and biofacies of the D Beds.
Fletcher, B.N. (1969). Lithological subdivision of the C Beds.
Rawson, P.F. (1971) on the Hauterivian biostratigraphy of the Speeton Clay.
Rawson, P.F. & Mutterlose, J. (1983). Stratigraphy of the Lower B and basal Cement Beds.
Mitchell, S.F. (1995). Lithostratigraphy and biostratigraphy of the Hunstanton Formation at Speeton.
Mitchell, S.F. & Underwood, C.J. (1999). Lithological and faunal stratigraphy of the Aptian and Albian of the type Speeton Clay.
Underwood, C.J. & Mitchell, S.F. (1999). Albian to basal Cenomanian onlap of structural highs in north-east England.
Hart, M.B., Price, G.D. & Smart, C.W. (2009). Foraminifera and sequence stratigraphy of the lower part of the Speeton Clay Formation.
Rawson, P.F. & Wright, J.K. (2000). The Yorkshire Coast, Geologists’ Association Guide No. 34.
British Geological Survey Lexicon entries for Speeton Clay Formation, Hunstanton Formation, Queens Rock Member, Speeton Beck Member, Dulcey Dock Member, Weather Castle Member, Red Cliff Hole Member and Ferriby Chalk Formation.
JNCC Geological Conservation Review accounts for Speeton Sands and Flamborough Head.