Speeton Cliffs - Fossil Collecting Guide (UK Fossils)

Speeton Cliffs are one of the most important Lower Cretaceous sites in the UK, with the highly productive Speeton Clay yielding ammonites, fish, shells and crustaceans. Often compared to the famous Folkestone Beds, the foreshore can be very rewarding under the right conditions. It is also a great location for families, although the clay can become extremely sticky and difficult underfoot in wetter months.

FIND FREQUENCY: ♦♦♦♦ – Speeton yields excellent ammonites and belemnites. Sometimes, these are found in nodules. However, shrimps and even reptile remains can also all be found, often during the scouring season or after heavy rains. In fact, fossils are very easy to find – you don’t need any tools – rather you can just pick them out of the clay.
CHILDREN: ♦♦♦ – This location is sometimes suitable for children. The problem is that the site changes frequently, with times of excellent access and other times of poor access with a steep descent. However, there is a lovely sandy beach for children to play on, which extends quite a way out. This can be an ideal day out for the family, but access may have to be made from Reighton.
ACCESS: ♦♦♦ – Access to Speeton is best from Reighton Sands and you can do both locations at the same time. Head to the Reighton Sands Holiday Village and park at the top of the cliff.
TYPE: Search for loose fossils on the foreshore after scouring conditions, keeping well clear of the cliffs, unstable scree and active mudflows.

DIRECTIONS

♦ Access is best by going to Reighton Gap and then walking to Speeton, which is not far.
♦ To the north of the village of Reighton, along the A165, you will see signs to the Reighton Sands Holiday Village. Take this road, passing the holiday village to Reighton Gap. You will come to a gravel car parking area with a walk down to the beach.
♦ The concrete slipway down is slipped, being cracked and worn with parts that are a little steep. Near the bottom, the path can be muddy and slippery. Once on the beach, walk southeast until you get to Speeton Cliffs.
♦ Postcode to Parking at Reighton Gap, YO14 9SN, Google Maps Link
♦ What3Words to Fossil Location: ///piled.polka.forwarded

VIDEO FILM

FOSSIL HUNTING

Speeton Cliffs is one of the most important Cretaceous fossil localities in Britain. The cliffs expose a thick succession of Lower Cretaceous marine clays and marls known as the Speeton Clay Formation, overlain by later Cretaceous chalk deposits. These beds have produced a remarkable variety of fossils including ammonites, belemnites, crustaceans, fish, reptiles, echinoids and microfossils. Search loose material on the open foreshore, well away from cliff bases and unstable scree. Rain and winter storms can release fresh fossils, but also increase instability; do not approach recent falls or active mudflows. Occasionally, strong tides scour the foreshore and expose fresh beds, which can provide excellent collecting opportunities.

Ammonites are among the most sought-after fossils at Speeton and occur in several horizons within the Speeton Clay. Species recorded from the site include Endemoceras regale, Polyptychites polyptychus, Kilianella, Hoplites, Deshayesites, Ancyloceras, Crioceratites, Acanthohoplites, Beudanticeras and Hamites. These ammonites represent a variety of shell forms, from tightly coiled species to more unusual heteromorph ammonites with loosely coiled or hooked shells. Some of the larger ammonites may be found within clay nodules or weathered from fallen blocks, while smaller specimens may occur loose in the clay debris at the base of the cliff.

Belemnites are characteristic fossils of the Speeton Clay, including Acroteuthis in the D Beds, Hibolites in the C Beds and Neohibolites in the A Beds. Their solid guards may weather free from the softer sediment. In Mitchell and Underwood’s 1999 revision, Neohibolites minimus is absent from the Speeton Clay and first appears higher in the local succession, in the Hunstanton Formation; a loose specimen therefore needs its original bed or matrix recorded before being used to date the clay.

The Speeton Clay has also produced a rich assemblage of marine invertebrates. Bivalves such as Inoceramus, Pecten, Aucellina and Gryphaea can occasionally be found, along with brachiopods and gastropods. Echinoids are present in some of the beds, and searching fallen blocks and clay nodules may reveal well-preserved specimens. Crustaceans are another notable feature of the site, and fossil shrimps such as Meyeria and Hoploparia have been recorded from these deposits.

Fish remains are also known from Speeton, typically preserved as isolated teeth, scales or bone fragments within the clay. These may include remains of early teleost fish as well as occasional shark material. Marine reptiles have also been discovered here, including ichthyosaurs and plesiosaurs, usually preserved as isolated bones or partial skeletons that have weathered from the clay beds. Because the clay is relatively soft, bones sometimes erode out naturally and can be found within the scree below the cliff.

Nearby chalk exposures also provide additional fossil opportunities. Both the Red Chalk and the White Chalk can be visited, where searching the foreshore boulders may reveal fossils such as echinoids, brachiopods and belemnites. Species such as Micraster and other chalk echinoids can occasionally be found weathered from these deposits.

Speeton is also scientifically important for its microfossils. The clay beds contain abundant foraminifera, ostracods and other microscopic fossils, which have been extensively studied to understand Early Cretaceous marine environments.

Because the cliffs are extremely unstable and prone to landslips, keep collecting to loose foreshore material well clear of their bases. Do not dig into the cliff or cross soft, active mudflows, and allow enough time to return along the shore before the tide blocks the route. With patience and careful searching, Speeton Cliffs can yield a remarkable diversity of Early Cretaceous marine fossils.

Some of the most significant fossil discoveries and scientific milestones from Speeton Cliffs include the earliest classic work on the Speeton Clay, the subdivision of the succession into the famous lettered beds, major ammonite and belemnite studies, and important marine reptile discoveries including the Speeton plesiosaur and the ichthyosaur Acamptonectes densus.

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.

1958 – the Speeton Clay ichthyosaur was collected
A team from the University of Hull collected the Speeton specimen in spring 1958. It later became the holotype of Acamptonectes densus. The separate specimen collected in 1985 was reported from Filey, so it should not be counted as a second discovery at Speeton Cliffs.

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.

2012 – Acamptonectes densus was formally described using the Speeton holotype
The new ichthyosaur was named from the Speeton specimen together with material from Filey and Germany. The study highlighted the survival of ophthalmosaurid ichthyosaurs across the Jurassic–Cretaceous boundary and established the scientific importance of the older Speeton collection.

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.

GEOLOGY

Speeton Cliffs exposes one of the most complete Lower Cretaceous successions in the UK and is internationally important for its record of Early Cretaceous marine environments. The cliffs consist mainly of the Speeton Clay Formation, a thick sequence of marine clays and marls deposited from the late Berriasian into the Albian during the Early Cretaceous. These sediments accumulated in a relatively deep offshore basin and record a long period of marine deposition. The clay weathers easily and is highly prone to landslips, which is why fresh material frequently falls to the base of the cliffs and becomes available for fossil collectors on the foreshore.

The Speeton Clay itself is composed of several distinct beds that represent changes in sea level, climate and sediment supply over millions of years. The clay is typically grey to dark grey and contains layers of nodules and harder concretions that often preserve fossils. These beds are well known for their rich ammonite faunas, along with belemnites, crustaceans, fish remains and marine reptile bones. Because the clay is relatively soft and easily eroded by rainwater, fossils are frequently washed out of the cliff face and accumulate in the scree slopes below.

The Speeton Clay is divided into the established E–A bed succession. Pale marls and limestone nodules occur at several levels, so a loose pale block should not be assigned to an unspecified “White Clay” unit near the base. The detailed account distinguishes the documented units and the changing positions of their exposures.

Above parts of the Speeton Clay sequence lies the distinctive Red Chalk, an unusually expanded local succession that marks an important transition in the geological record. The Red Chalk is coloured by iron oxides and represents a condensed deposit formed during a period of slow sedimentation in the mid-Cretaceous seas. It is divided locally into five formal members and contains fossils such as belemnites, echinoids and brachiopods.

Overlying the Red Chalk is the White Chalk, which forms part of the Chalk Group that dominates much of eastern England. These chalk deposits were formed from the accumulation of microscopic calcareous plankton settling to the seabed in a warm, clear Cretaceous sea. The chalk beds are much harder than the underlying clay and can be seen in places along the foreshore as fallen blocks. Fossils within the chalk include echinoids, brachiopods and belemnites, which can sometimes be found weathered from the boulders scattered along the beach.

Together, the Speeton Clay, Red Chalk and White Chalk record a long history of changing marine environments from the Early into the Late Cretaceous, from offshore clay deposition to the clearer, plankton-rich seas that later produced the great chalk deposits of northern Europe. Continuous coastal erosion along the cliffs exposes fresh sections of these rocks, making Speeton one of the most scientifically significant geological sites on the Yorkshire coast.

Speeton Cliffs composite, Reighton/New Closes through Buckton: schematic geological table, youngest at top and not to scale. — Schematic geological framework, not to scale. View full-size geological chart.

This is a detailed composite stratigraphic breakdown of Speeton Cliffs, North Yorkshire, the classic reference section for the Speeton Clay Formation and the most important exposed marine Lower Cretaceous succession of the North Sea Basin in Britain. The section is not a single continuous clean cliff log, but a shifting foreshore-and-landslip composite extending from Reighton Gap to Buckton, and it passes upward from Kimmeridge Clay into the full Speeton Clay succession, the expanded Hunstanton Formation and the basal Ferriby Chalk.

The amber Ancholme Group bar applies only to the Kimmeridge Clay. The Speeton Clay and Hunstanton formations have no assigned parent group in the adopted BGS framework. Different published alphanumeric schemes are identified separately below; their finer divisions are not silently merged.

Mitchell and Underwood abandoned the old name “Minimus Marls”: Neohibolites minimus is absent from the Speeton Clay in their revision and first appears higher in the Hunstanton Formation. Their Upper A Beds begin with the Greensand Streak, UA4. Slips can repeat this horizon, so apparent repeated green beds do not establish repeated depositional units.

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.

ANCHOLME GROUP

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 Pectinatites 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, Aulacoteuthis 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.

Individual Lower D Beds — Neale’s Published Speeton Composite

The order below runs from D8 above the Coprolite Bed upwards to D6A. Original inch values and observed ranges are retained; they are published composite-section measurements, not a new continuous measurement of today’s slipping cliff. Subdivisions are beds, not formal members. The Neale scheme distinguishes these individual units within the broader D-bed descriptions.

D8 — 12 in

Hard black shale; glauconite and quartz grains.

D7G — 17–18 in

Brown, glauconitic clay and mudstone.

D7F — 3 in

Blue clay, pale mottling.

D7E — 4½ in

Green-brown shaly mudstone. Neale’s 1962 collection records Laugeites? sp. at this, the lowest ammonite-bearing level in that study.

D7D — 6½–8 in

Blue clay; pyrite nodules and greenish burrows.

D7C — 8–9½ in

Green-black blocky shale.

D7B — 6 in

Grey-blue streaked mudstone. Neale records Tollia wrighti here and states that the D7A association also occurs in the underlying bed.

D7A — 10 in

Green-black shaly mudstone. Neale’s historical identifications include Tollia wrighti, Paracraspedites prostenomphaloides and Laugeites? sp.; the text also records them in D7B below.

D6J — 5–6 in

Soft blue clay; yellow efflorescence on weathering.

D6I — 18½–22 in

Pale-blue mudstone. Small ammonites were identified by Neale as Subcraspedites aff. cristatus. This retains the original identification and bed provenance, not a claim that the historical generic assignment remains current.

D6H — Stone Band — 4–7 in

Hard pale limestone lenticles form a conspicuous marker between similar mudstones. Neale reports Paracraspedites stenomphaloides, using that spelling and historical identification.

D6G — 8 in

Pale-blue shale with blocky fracture. Neale records Paracraspedites subtzikwianus from this bed; this is the historical identification in the 1962 account.

D6F — 3½ in

Shaly mudstone darker than D6G.

D6E — 4 in

Dark mottled shale.

D6D — 3¾ in

Pale-blue mudstone.

D6C — 2¼ in

Dark shale.

D6B — 2 in

Pale streaked muddy band.

D6A — 22 in In Neale’s Composite

Pale bluish-buff mudstone with two ammonite-bearing levels, subdivided in Neale’s original account. The sub-beds below retain his top-down Greek suffixes and published measurements, rather than being forced into an exactly summed modern measurement.

D6A α — 1 in

A thin bed at the junction with D5.

D6A β — 7 in

Brown laminated mudstone with pale-green mottling. Neale records Tollia stenomphala and T. cf. tolmatschowi.

D6A γ — 1–2 in

Strongly mottled sediment between β and δ.

D6A δ — 13 in

Greenish or bluish, relatively homogeneous mudstone with darker streaks or large mottles; it breaks into blocks. Neale records Tollia pseudotolli and large bivalves.

Beds D5–D4 — Lingula Bed And Astarte Bed Interval

Higher in the D Beds, the dark-brown Lingula 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.

Upper D Marker Horizons In The Hull Geological Society Field Log

The field log records named and lettered horizons within the Speeton coastal composite. It is a schematic logged succession, not a continuously exposed Reighton cliff or a new numerical thickness survey. Its labels are retained without inventing a correlation between every historical sub-bed scheme.

D5 — Lingula Bed

Dark-brown clay forms the marked Lingula horizon above the lower D succession.

D4B — Pale Stripe

The field log distinguishes a pale stripe within the D4 clay interval; it does not provide a separately written lithological description for every adjoining D4 sub-bed.

D3A — Exogyra Horizon

Pale sediment and brown nodules mark the Exogyra-bearing horizon. A further drawn nodule level is labelled D3E in this field scheme; it is not silently renamed to fit another author’s subdivision.

D2D — Remanié Horizon

Dark glauconitic sediment forms the recorded reworked horizon below D1.

D1 — Compound Nodular Bed

The upper-D marker is the compound nodule horizon. Its distinctive multistage nodules are retained in the detailed account above; no unverified sub-bed thickness is added.

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.

Lower C Field-Log Markers

These individual descriptions follow the Hull Geological Society field-log annotations. They are retained at their recorded detail; no thickness is read off the schematic scale, no missing label is invented, and blank annotations are not filled with conjectural sedimentology.

C11A

Green clay.

C10

Pale sediment.

C9D

Dark clay with basal brown nodules.

C9C

Pale-grey sediment with brown nodules.

C9A

Pale clay with brown nodules; a darker intervening interval is drawn below.

C8A — Nodular Marker

The HGS lower-C field log distinguishes a nodular marker in C8A. No thickness is inferred from the schematic drawing.

C8B — Dark Interval

The same field log explicitly annotates C8B as dark, separately from the C8A nodular marker.

C7F–H

Pale-grey silty clay with brown nodules and an occasional limestone near the top.

C7A

Brown silty clay with nodules and large ammonites.

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.

Middle C Field-Log Markers

Dark sediment.

C5L

Brown-weathering marker.

C5K

Brown nodules.

C5J

Olive-grey sediment.

C5H–I

Pale intervals.

C5G

Brown-weathering horizon with large nodules.

C5D

Dark-grey sediment.

C5C

Dark sediment.

C5B

Olive-grey sediment.

C5A

Dark sediment.

C4L

Brown-weathering marker.

C4K

Dark glauconitic interval.

C4J

Brown-weathering nodular marker.

C4I

Dark pyritic shaly clay.

C4H

Brown-weathering horizon with small nodules.

C4G

Dark interval.

C4F

Pale interval.

C4D

Green-yellow sediment with a possible limestone.

C4C

Pale interval.

C4B

Dark glauconitic interval.

C4A

Brown-weathering limestone.

C3B

Calcareous nodules; adjoining C3A,C3C and C3D are separately labelled without written lithological elaboration.

C2FI And C2FII

The field log distinguishes C2FI and C2FII. Its shaly, pyritic annotation is attached to C2FII; that description is not extended to C2FI without separate evidence.

C2E

Brown-weathering nodular marker.

C2D

Dark glauconitic sediment.

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.

Lower B Field-Log Subdivisions

LB6

Pale sediment.

LB5E

Black interval.

LB5D

Dark sediment.

LB5C

Pale–medium-grey–pale succession.

LB5B

Dark interval.

LB5A

Pale nodular horizon.

LB4A–C

Pale upper intervals contrast with black LB4C; the drawing does not quantify each sub-bed.

LB3E

Pale interval.

LB3A

A thick drawn interval with scattered nodules; finer named boundaries are retained as field-log labels rather than invented measurements.

LB2D

Thin marker drawn below LB2CII.

LB2CII

Dark interval.

LB2B

Nodular marker.

LB2AII

Very dark sediment.

LB2AI

Dark sediment with yellow colour at its base.

LB1E

Pale nodular interval; neighbouring LB1D and LB1F are labelled but not given separate written descriptions.

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.

Middle B Cementstone Markers

Field Bed 50

Double cementstone bands.

Field Bed 48

Small brown-weathering cementstones.

Field Bed 47

Dark clay.

Field Bed 46

Pale clay.

Field Bed 45

Dark interval.

Field Bed 44

Pale sediment with large cementstones.

Field Bed 40

Dark sediment.

Field Bed 35

Very dark clay.

Unexposed Middle-B Interval

A gap above the labelled33–34 interval represents further Middle B with cementstones. No continuous measured connection is asserted.

Upper B

Black, very pyritic clay with brown bands and streaks; the finer UB scheme is separately described in the following source-based account.

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.

The revised upper-B log distinguishes the following beds. UB2 and UB1 have not been observed in contact: an interval of unknown thickness must remain between them, rather than being filled with an invented bed.

Undifferentiated Upper B — at least 4 m; neither boundary seen

Soft black laminated shale, pyritic nodules, abundant belemnites and pyritised ammonites; pale interbeds contain calcareous concretions.

UB3 — at least 0.4 m; base unseen

Soft black shale with abundant pyrite nodules.

UB2C — 0.15 m

Pale brown-grey shale with phosphatised ammonites; gradational base.

UB2B — less than 0.15 m

Brown sandy clay with sandy septaria, sand-filled Planolites and abundant phosphatised ammonites; sharp base.

UB2A — at least 0.13 m; top unseen

Lower UB2Ai is dark shale with flattened ammonites and sand-filled burrows; upper UB2Aii is 0.03 m of nodular siltstone with dark Chondrites.

UB1C — at least 0.20 m; base unseen

Lower UB1Cii is 0.05 m hard black mudstone; upper UB1Ci is 0.15 m black shale.

UB1B — 0.25 m

Dark hard marl with pyrite, partly pyritised ammonites and gastropods; abundant planktonic foraminifera appear upwards.

UB1A — 0.40 m

Dark shaly marl with flattened phosphate nodules; uppermost UB1Ai is 0.05 m of burrowed black shale.

Lower A Beds — Ewaldi Marl And Overlying Shaly Mudstone

In the revised LA scheme, basal LA6 is a thin belemnite-and-phosphate conglomerate above a burrowed surface. The overlying LA5 subdivisions form pale, burrowed Ewaldi Marl with belemnites and inoceramid bivalves. An unexposed interval of unknown thickness separates these from the higher dark shaly mudstones of LA3, LA2 and LA1. Consequently the original older sequence of “basal sand, black marl, then Ewaldi Marl” should not be treated as the order of these revised Lower A Beds. The full Aptian–Albian succession is reconstructed from discontinuous exposures and includes erosional breaks.

The revised Lower A scheme is given in upward order. LA5 is separated from LA3 by an unobserved interval of unknown thickness. LA4 was deliberately left vacant by the authors; it is not a missing known bed to be invented.

LA6 — 0–0.10 m

Lenticular belemnite/phosphate conglomerate in pale marl; burrows extend into the B Beds, even where the conglomerate is absent.

LA5iii — 0.60 m

Hard grey, locally greenish, burrowed marl; belemnites and inoceramids common.

LA5ii — 0.20 m

Softer yellow-grey marl with greenish patches and burrow linings.

LA5i — at least 0.50 m; top unseen

Massive pale-grey/yellow marl; fewer belemnites and inoceramids. All LA5 subdivisions have sharp but burrowed bases.

LA3vi — at least 0.10 m

Hard brown clay with rare nodules; base of the full LA3 interval unseen.

LA3v — 0.40 m

Medium-brown shale.

LA3iv — 0.25 m

Soft dark-brown shale.

LA3iii — 0.20 m

Harder brown burrowed clay; nodules locally common.

LA3ii — 0.60 m

Dark-brown burrowed shale with scattered nodules.

LA3i — 0.40 m

Soft black shale with occasional nodules.

LA2 — 0.20 m

Hard black shale with flattened burrows and glauconitic, micaceous clay lenses; sharp burrowed base.

LA1iii — 0.30 m

Soft black shale.

LA1ii — 0.25 m

Dark-brown shaly clay with rare possibly reworked phosphates.

LA1i — 0.15 m

Brown clay, phosphates locally common; the upper LA1 is penetrated by burrows from the overlying bed.

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 Calcareous Clays (Historical “Minimus Marls”)

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 Neohibolites belemnites, 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.

Upper A beds are listed from the basal Greensand Streak upwards. Partial thicknesses and non-observed contacts are preserved. Roman sub-bed suffixes identify only the subdivisions actually described in the source.

UA4 — Greensand Streak — 0.05–0.20 m

Highly glauconitic green clay with reworked black phosphates, piped into underlying burrows; slips may repeat the bed.

UA3C — 0.10–0.30 m

Red glauconitic clay with calcareous and phosphatic nodules, some baryte-coated; upper UA3Ci can be 0.12 m of smooth, non-glauconitic red clay.

UA3B — 0.90 m

Brown bioturbated clay; a local 0.15 m micritic limestone, UA3Bii, lies 0.12 m above the base and grows around baryte-coated phosphates.

UA3A — 0.70 m

Brown burrowed clay; black seams under 0.05 m thick occur at the base (vi) and middle (iv,ii). Belemnites become common from iii.

UA2C — 0.45 m

Red/pink calcareous clay with scattered, sometimes baryte-coated phosphates. Thin black seams occur at the base (iv) and middle (ii).

UA2B — 0.12 m

Grey-green clay densely penetrated by red Chondrites.

UA2A — 0.20 m

Red calcareous clay.

UA1C — 1.75 m

Brown bioturbated clay with phosphates; black burrowed UA1Civ (0.10 m) lies 0.50 m above the base, followed 0.20 m higher by red burrowed UA1Cii (0.10 m).

UA1B — at least 1.0 m; top unseen

Brown clay alternating with at least three red-marl beds. Only deformed exposures were seen; no further subdivision was attempted.

UA1A — probably at least 1.0 m; base unseen

Grey/brown burrowed marly clay with inoceramid shell concentrations. Small isolated exposures predominate; the upper 0.30 m was seen beneath the Hunstanton Formation.

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.

Individual Published Beds — Queens Rock Member

The following descriptions and thicknesses follow the individual Speeton sections in BGS RR/06/01, rather than measurements made on a present-day continuous cliff face. The HC prefix used in that report denotes its Hunstanton-bed scheme.

HC-QR1 (0.80 m)

Red marl with glauconite streaks and grey-filled Planolites and Chondrites burrows.

HC-QR2 (1.20 m)

Red marly chalk with scattered red and pink nodules; the lower member ends at the ensuing erosion surface.

HC-QR3 (c.1.90 m)

Dark-red marly chalk with six sparse nodular levels, Chondrites and common Inoceramus anglicus.

HC-QR4 (0.25 m)

Three bands of white chalk nodules.

HC-QR5 (0.45 m)

Red marly chalk.

HC-QR6 (0.05 m)

White chalk nodules.

HC-QR7 (0.30 m)

Red marly chalk at the top of the member.

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.

Individual Published Beds — Speeton Beck Member

HC-SB1 (0.50 m)

Grey and red marly clay, abundantly burrowed by Chondrites and Planolites.

HC-SB2 (0.20 m)

Red marl with occasional white chalk nodules.

HC-SB3 (0.16 m)

White chalk.

HC-SB4 (0.40 m)

Red marly clay with grey-filled Chondrites and Planolites burrows.

HC-SB5 (0.20 m)

Grey marl passing into grey chalk with a nodular top and dark-red burrow fills.

HC-SB6 (0.06 m)

Red marly clay.

HC-SB7 (0.20 m)

Grey marl passing into nodular-topped grey chalk; abundant dark-red Chondrites and Planolites fills.

HC-SB8 (0.06 m)

Grey marly clay, with abundant Chondrites in its upper part.

HC-SB9 (0.08 m)

Grey chalk with a Thalassinoides-burrowed upper surface.

HC-SB10 (0.04 m)

Grey-pink marl with Chondrites and Planolites.

HC-SB11 (0.08 m)

Grey-pink chalk with a Thalassinoides-burrowed top.

HC-SB12 (0.13 m)

Red-grey marl.

HC-SB13 (0.18 m)

Pale-red chalk with a Thalassinoides-burrowed top.

HC-SB14 (0.17 m)

Red marl, increasingly nodular upwards, particularly in its middle part.

HC-SB15 (0.30 m)

Red nodular chalk with a local chalk-pebble scour at the top.

HC-SB16 (0.35 m)

Chalky red nodular marl passing into red chalk.

HC-SB17 (0.24 m)

Red chalk becoming increasingly nodular upwards.

HC-SB18 (0.20 m)

Red nodular chalk rich in Inoceramus lissa; Neohibolites ernsti and N. praeultimus occur at the top.

HC-SB19 (0.15 m)

Soft red marl.

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.

Individual Published Beds — Dulcey Dock Member

HC-DD1 (0.49 m)

Marly chalk with abundant Inoceramus lissa fragments and crinoid columnals.

HC-DD2 (0.92 m)

Marly chalk with two conspicuous nodular horizons.

HC-DD3 (0.16 m)

Two white nodular chalk bands separated by red marl; Biplicatoria hunstantonensis present.

HC-DD4 (0.78 m)

Weakly nodular marly chalk with a pale nodule band.

HC-DD5 (0.26 m)

Two bands of fractured and reworked white nodules separated by red nodular marl: the Breccia Nodule Band.

HC-DD6 (0.19 m)

Dark-red clay overlain by red nodular chalk.

HC-DD7 (0.28 m)

Red nodular marl overlain by red nodular chalk.

HC-DD8 (0.20 m)

Red marl passing up into white chalk.

HC-DD9 (0.19 m)

Red nodular marly chalk passing up into white chalk.

HC-DD10 (0.13 m)

Red nodular marl passing into white nodular chalk.

HC-DD11 (0.19 m)

Red nodular marl passing into white nodular chalk.

HC-DD12 (0.15 m)

Red nodular marl passing into white nodular chalk.

HC-DD13 (0.16 m)

Red nodular marl overlain by red nodular chalk.

HC-DD14 (0.23 m)

Red nodular marl passing into pale-red chalk; first common Aucellina in this log.

HC-DD15 (0.37 m)

Red marl, nodular red marl and red chalk in upward sequence.

HC-DD16 (0.27 m)

Red marl passing into red marly chalk that whitens towards the top.

HC-DD17 (0.15 m)

Red nodular chalk overlain by pale chalk.

HC-DD18 (0.23 m)

Red nodular marl overlain by pale-red chalk.

HC-DD19 (0.17 m)

A well-developed marl beneath red chalk.

HC-DD20 (0.21 m)

Shelly red nodular marl passing into pale-red chalk.

HC-DD21 (0.27 m)

Red nodular marl passing into white nodular chalk.

HC-DD22 (0.43 m)

Red nodular marl passing into nodular chalk.

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.

Individual Published Beds — Weather Castle Member

HC-WC1 (0.35 m)