Watton Cliff Fossil Hunting

1836 – early geological attention
The Watton Cliff coast, between Eype Mouth and West Bay, had entered formal geological study by the 1830s. This early recognition helped establish the cliff as an important Middle Jurassic section rather than just a local stretch of unstable coast.

1894–1898 – first detailed cliff descriptions
Late 19th-century geological survey work gave the first detailed descriptions of the Watton Cliff succession. These accounts recorded the relationship between the clays, limestones and shelly beds that are now placed in the Frome Clay and Forest Marble formations.

1916–1922 – Watton Cliff name and Junction-Bed study
S.S. Buckman investigated the cliffs after finding fossiliferous material at Fault Corner in 1916, returning in later years before publishing his account in 1922. He used the name Watton Cliff from Watton Farm behind the coast, helping fix the geological name for a section also known locally around West Cliff, Ware Cliff, Clay Knapp and Fourfoot Hill.

1933 – near-complete Forest Marble succession recognised
The former presence of a small Cornbrash remnant on the cliff top showed that the Forest Marble succession at Watton Cliff was probably almost complete. This made the locality especially useful for understanding the upper Bathonian rocks of west Dorset.

1936–1941 – Wattonensis Beds established
The brachiopods Rhynchonelloidella wattonensis and Wattonithyris wattonensis became central to defining the Wattonensis Beds, a fossil-rich marker horizon at the base of the Frome Clay. Watton Cliff is the type locality for these beds, making the site important for regional Bathonian correlation.

1957–1959 – microfossils and ammonites expanded the record
Microscopic fossils from Watton Cliff, including holothurian sclerites and foraminifera, were described during the late 1950s. In the same period, ammonite work included the holotype of Procerites wattonensis from the Wattonensis Beds, adding useful dating evidence to the brachiopod-rich marker horizon.

1969 – bed-by-bed framework refined
A modern bed-numbered framework was set out for the Forest Marble and underlying beds at Watton Cliff. This made it easier to place fossils, including material from the Boueti Bed and Mammal Bed, into a precise position within the cliff succession.

spring 1970 – fossiliferous shore blocks found
Blocks from the Forest Marble were found on the shore below Watton Cliff and proved to contain a varied fossil assemblage, including crinoid material, shark teeth and rare crocodilian remains. These finds drew attention to the vertebrate potential of the fallen and slipped Forest Marble blocks.

1970 – trace fossils interpreted
Trace fossils from the upper Forest Marble at Watton Cliff, including Gyrochorte and Imbrichnus wattonensis, were used to interpret the shallow-marine environment. The work showed that the ripple-marked and burrowed sandstone tiles were evidence of changing water energy and seafloor activity, not just decorative markings in fallen blocks.

1976–1977 – first mammal and tritylodont records
Mammalian teeth were recorded from the Watton Cliff Mammal Bed, followed by a single tritylodont tooth identified as Stereognathus. These discoveries established Watton Cliff as one of the few British Middle Jurassic localities to yield important small mammal and mammal-relative remains.

1977 – Liassic palaeofault recognised
Work on the older beds faulted against the Watton Cliff section showed evidence for Jurassic movement on a palaeofault, including abrupt thickness changes and mineral-filled fissures with Toarcian ammonites. This added structural importance to the locality as well as its better-known Bathonian fossil record.

late 1970s – Mammal Bed bulk sampling
A University College London team excavated and processed material from the Mammal Bed as part of work on Middle Jurassic tetrapod assemblages. Bulk sieving and acid preparation recovered small sharks, bony fish, amphibians, reptiles and mammals, turning Watton Cliff into a key microvertebrate locality.

1981–1983 – Mammal Bed environment explained
Detailed sedimentological work interpreted the Mammal Bed as a shell-rich, high-energy deposit with channels and storm-washed debris. This explained why Watton Cliff preserves a mixed assemblage of marine fossils, plant material and transported land vertebrate remains in the same Forest Marble horizon.

1985 – Lissodus sharks described
Two small hybodont sharks, Lissodus wardi and Lissodus pattersoni, were described from Mammal Bed material, with the holotype of Lissodus wardi from Watton Cliff. These teeth strengthened the site’s importance for tiny shark faunas as well as for mammals and amphibians.

1992–1994 – transported tetrapod assemblage clarified
Studies of the Forest Marble microvertebrates showed that Watton Cliff contains a marine fish component together with water-worn amphibian, reptile and mammal remains transported from land or freshwater settings. This helped explain the unusual mixture of fossils found in the Mammal Bed.

1995 – ammonite dating and lithostratigraphy refined
The Watton Cliff Frome Clay succession was reinterpreted within a modern stratigraphic framework, and ammonites from the Wattonensis Beds were used to recognise the Upper Bathonian Quercinus Subzone. The holotype of Procerites wattonensis was also reassessed in relation to Procerites quercinus, tightening the dating of the section.

1998 – Eleutherodon oxfordensis added to the mammal record
Allotherian mammal teeth from Watton Cliff were included in the record of Eleutherodon oxfordensis. Although based on tiny isolated teeth, the material added to the site’s importance for early mammal evolution in the British Middle Jurassic.

1999–2002 – national site importance recognised
Watton Cliff was recognised as a nationally important site for fossil fishes, mammals, birds and Middle Jurassic stratigraphy. Its value rests on the best Bathonian exposure in Dorset, the type locality of the Wattonensis Beds, the Boueti Bed marker horizon and the Mammal Bed microvertebrate fauna.

2003 – docodont and trechnotherian mammals recorded
The Watton Cliff mammal fauna was expanded with records including Borealestes serendipitus and indeterminate trechnotherian material. These rare teeth added further diversity to the Mammal Bed and linked Watton Cliff with other important British Middle Jurassic microvertebrate sites.

2005 – further allotherian teeth described
Additional allotherian mammal teeth from the Forest Marble were described, including Watton Cliff specimens from the Mammal Bed. The work helped clarify the early record of multituberculate-like mammals and showed that Watton Cliff continued to provide evidence from very small, easily overlooked fossils.

2011 – Wattonensis Beds formalised in modern usage
The Wattonensis Beds were treated as a formal local unit with Watton Cliff as the stratotype. This reinforced the site’s role as the reference point for a distinctive brachiopod-rich Bathonian marker bed within the Frome Clay.

2016 – new triconodont mammals named
Triconodont mammal teeth from Watton Cliff and related Forest Marble sites were revised, with Watton Cliff providing type material for Morganucodon tardus, Stylidens hookeri and Phascolotherium simpsoni. These tiny teeth made the locality especially important for understanding Middle Jurassic mammal diversity.

2024 – ornithischian dinosaur teeth reviewed
Five isolated ornithischian dinosaur teeth from Watton Cliff were included in a wider study of British Bathonian microvertebrate faunas. The record shows that small dinosaur remains were also washed into the Forest Marble depositional system, adding another terrestrial element to the Mammal Bed story.

Section Architecture

Watton Cliff is not a single simple vertical cliff log. The section extends for about 750 m between Eype Mouth and the River Brit and is affected by landslip, beach masking and faulting at both ends, so some parts are only intermittently visible. The Bathonian succession, comprising the Frome Clay Formation overlain by the Forest Marble Formation, is faulted against older Lias Group rocks to east and west, and the type locality of the Wattonensis Beds is now exposed only in restricted places near the Eype Mouth Fault and within the West Cliff Fault shatter belt.

Stratigraphic Note

Published bed numbers exist for this section. The Frome Clay and Forest Marble bed numbers used below are those of Torrens and later summaries based on Wilson, Holloway and Callomon & Cope. The older Woodward log uses a different numbering system, and the famous Mammal Bed calcirudites of Woodward’s Bed 8 correspond broadly to the middle shell-bank complex of the modern Forest Marble scheme. The succession is upper Bathonian throughout, with the Frome Clay placed in the Quercinus Subzone and the Forest Marble correlated more broadly by its marker beds and lithological position within the late Bathonian succession.

GREAT OOLITE GROUP

Frome Clay Formation (Upper Bathonian)

Wattonensis Limestone Member

Bed WC1 — Wattonensis Beds / Torrens Bed 1 (seen to c. 8 m)

The Wattonensis Beds form the basal and most famous part of the Frome Clay succession at Watton Cliff. They consist of alternating clays and thin muddy limestones, richly fossiliferous and dominated by brachiopods, especially Acanthothiris powerstockensis, Rhynchonelloidella, Rugitela, Tubithyris and Wattonithyris, together with bivalves such as Catinula knorri, Modiolus anatinus, Parallelodon and Trigonia elongata. Sparse ammonites include the specimen originally named Procerites wattonensis, later regarded as close to P. quercinus, and this is why the Watton Cliff Frome Clay is assigned to the Quercinus Subzone. The member is the type locality of the Wattonensis Beds but is now only intermittently visible because of shingle cover, landslip and fault disruption. Depositional environment: quiet offshore calcareous mud accumulation with recurring shelly, bioturbated limestone interbeds on a low-energy shelf.

Bed WC2 — Oyster Bed / Torrens Bed 2 (0.75 m)

A clay bed rich in small or broken Praeexogyra hebridica. This is one of the two oyster-rich levels recognised in the Dorset Frome Clay above the Wattonensis member and provides a useful marker within the lower part of the formation. The abundance of disarticulated small oysters indicates a quiet muddy sea floor that was periodically colonized by dense oyster populations and then disturbed or reworked just enough to break and concentrate shells without converting the bed into a true shell gravel.

Bed WC3 — Covered Gap / Torrens Bed 3 (at least c. 12 m, probably more)

A substantial covered interval occurs above the Oyster Bed. Buckman estimated this missing thickness at about 12 m, but later workers regarded that as probably an underestimate. Because this interval is not honestly visible in modern exposure, it should remain a documented gap rather than be turned into a spurious detailed local log. It represents a large part of the lower to middle Frome Clay succession.

Bed WC4 — Torrens Bed 4, Marly Clay To Beach Level (6.0 m)

Grey to blue-grey marly clay forms a thick, rather featureless middle part of the exposed Frome Clay. Although not as conspicuously fossiliferous as the Wattonensis Beds below, it belongs to the same broad offshore mudstone regime and records continued deposition below fair-weather wave base. Fossils are comparatively sparse and exposure quality is usually poor, but the bed is important because it shows that the Frome Clay at Watton Cliff is not merely a thin brachiopod bed below the Forest Marble, but a substantial clay formation in its own right.

Bed WC5 — Torrens Bed 5, Alternating Pale Fine-Grained Limestones And Marl (0.45 m)

A thin but distinctive alternation of pale argillaceous fine-grained limestone and marl interrupts the more monotonous clays below and above. It represents a brief phase of more calcareous sedimentation within the Frome Clay sea and may reflect slower mud input, enhanced carbonate production or both. The bed is significant mainly as an internal marker in the upper part of the formation.

Bed WC6 — Torrens Bed 6, Main Blue-Grey Marl (16.4 m)

This thick blue-grey marl is the dominant upper unit of the exposed Frome Clay at Watton Cliff. It is calcareous, predominantly fine-grained and relatively uniform, though locally fossiliferous and bioturbated. The great thickness of this interval is one reason the Watton section is so valuable, because the Frome Clay is much less well exposed in its inland type area and commonly known there only from boreholes. Depositional environment: prolonged offshore mud accumulation in a quiet shelf sea, with only subordinate limestone development and no sign yet of the sandy, shell-bank conditions of the Forest Marble above.

Bed WC7 — Torrens Bed 7, Laminated White Argillaceous Limestone (1.5 m)

A conspicuous white, fine-grained, laminated argillaceous limestone near the top of the Frome Clay. The bed is more indurated and laterally obvious than much of the formation below and marks a short-lived calcareous phase close to the transition into the Forest Marble. Its lamination and pale colour contrast with the darker marls beneath.

Bed WC8 — Torrens Bed 8, Upper Shaly Blue Marl (1.5 m)

Blue shaly marl forms the highest exposed Frome Clay directly beneath the Boueti Bed. The top of this unit may contain burrows, and the Boueti Bed above rests non-sequentially on it. This final marl interval records the last offshore-mud phase before the abrupt late Bathonian facies change into the mixed shell-bank, sandstone and limestone environment of the Forest Marble.

Total Thickness Of Frome Clay Formation Represented At Watton Cliff: More Than 46 Metres In Composite, Because The Central Covered Gap Alone Is At Least About 12 Metres Thick And May Be Greater

Forest Marble Formation (Upper Bathonian)

Forest Marble Note

The Forest Marble at Watton Cliff is the most complete section of the formation in west Dorset and can be divided into three broad lithological packages: a lower muddy and sandy shell-bearing unit, a middle coarse shell-bank and calcirudite complex, and an upper muddy sandstone-and-clay unit with exceptionally varied trace fossils. Direct ammonite evidence in the Forest Marble at Watton itself is sparse, so detailed age control relies mainly on correlation by the Boueti Bed and the higher calcirudite interval with the better-dated east Dorset succession.

Bed WC9 — Boueti Bed (unnumbered basal Forest Marble marker; 0.35 m)

The Boueti Bed forms the base of the Forest Marble Formation and is one of the two great marker horizons of Watton Cliff. It is a hard, whitish to reddish-brown weathering shelly calcareous marl or argillaceous micrite rich in brachiopods, especially Goniorhynchia boueti, together with terebratulids, bivalves such as Camptonectes laminatus, Chlamys vagans, Praeexogyra hebridica, Trigonia costata and Vaugonia impressa, gastropods including Pleurotomaria burtonensis and Turbo burtonensis, crinoid debris of Apiocrinus elegans, serpulids, bryozoans and rare corals. Large Thalassinoides burrow networks occur at the base. The bed is a widespread late Bathonian datum that can be traced northwards into Somerset and the southern Mendips, and it rests non-sequentially on the Frome Clay below. Depositional environment: very slow shell-rich sedimentation on a shallow marine shelf floor with firmground development and strong benthic colonization.

Bed WC10 — Torrens Bed 1, Lower Forest Marble Blue-Grey Shale With Calcirudite And Calcarenite Lenses (12.0 m)

The lowermost major unit of the Forest Marble is a thick blue-grey shale and clay interval containing lenses of brownish-grey fissile calcirudite and calcarenite. One especially notable body occurs about 6.6 m above the base, where a wedge-shaped lens about 200 m long thins and fines laterally from coarse 0.35 m-thick calcirudite to 0.10 m-thick calcarenite. This unit is the muddy lower part of the Forest Marble and shows that the formation did not begin as a uniform limestone shelf. Instead, shell-detrital sand bodies and thin channelised banks were emplaced intermittently within a mainly muddy shelf setting. Depositional environment: shallow-marine muddy shelf receiving episodic shell-bank and calcarenitic storm deposits.

Bed WC11 — Torrens Bed 2, Calcarenitic Laminated Shale With Silt Streaks (1.8 m)

A thinner but distinctive interval of laminated calcarenitic shale with silt streaks. It records continued mixed mud, fine shell-debris and very fine clastic input. The lamination and silt wisps suggest fluctuating low-energy conditions, but the calcarenitic character shows that shell detritus was still being supplied to the site from nearby shoal or shell-bank accumulations.

Bed WC12 — Torrens Bed 3, Hard Argillaceous Fine-Grained Limestone (0.3 m)

A hard cream-weathering argillaceous limestone forming a prominent marker bed. This bed likely represents a short phase of sea-floor stabilization and carbonate lithification between muddier Forest Marble intervals. Its persistence and hardness make it one of the more useful small-scale markers in the lower part of the formation.

Bed WC13 — Torrens Bed 4, Blue Clay With Silt Streaks (0.5 m)

A relatively thin return to blue clay with silt streaks, lying immediately below the main calcirudite complex. The bed is important because it separates the lower muddy Forest Marble from the central coarse shell-bank facies above and shows that the onset of the Mammal Bed shell-bank complex was abrupt rather than gradual.

Bed WC14 — Torrens Bed 5, Main Calcirudite / Mammal Bed (c. 2.0 m In The Simplified Torrens Log; Part Of A Broader 3–5 m Calcirudite Facies In Other Treatments)

This is the most important single bed-package in the whole Watton Cliff section. It consists of massive shell-fragmental and locally ooidal limestone, flat-bedded and cross-bedded in places, with irregular clay seams, ochreous galls, lignite, bored pebbles of grey micrite and sparsely ooidal micrite, abundant broken or disarticulated pectinids and oysters, common crinoid columnals, shark teeth and large logs of carbonized wood up to about 1 m long. This is the classic Mammal Bed calcirudite of the Watton Cliff literature. Microvertebrate bulk sampling from these impersistent sheets and lenses recovered a mixed fauna of marine fishes and reworked terrestrial or marginal-terrestrial tetrapods. Characteristic fish and shark remains include Asteracanthus, Hybodus, Polyacrodus, Lissodus wardi, L. pattersoni, Spathobatis, Protospinax, Heterodontus, an orectolobid, ?Palaeocarcharias, Scyliorhinus, Lepidotes and pycnodontids. Amphibians include Eodiscoglossus oxoniensis, Marmorerpeton and albanerpetontids; reptiles are diverse but usually fragmentary; mammals include Eleutherodon oxfordensis, Amphilestes broderipii, Borealestes serendipitus, trechnotherian material and a tritylodont tooth referred to Stereognathus. The tetrapod remains are commonly abraded, showing transport into a high-energy offshore shell-bank complex. Depositional environment: unstable shallow-marine shell shoals and channels repeatedly reworked by storms, with terrestrial debris and vertebrate material flushed seaward through storm-breach channels in an offshore bank system.

Bed WC15 — Torrens Bed 6, Clay And Shale With Shelly Limestone Lenses And Ripple-Marked Sandstone (6.0 m)

Above the calcirudite complex the Forest Marble returns to a dominantly muddy and shaly facies. Shelly limestone lenses occur throughout, and laminated sandstone leaves preserve ripple marks. Ferruginous staining is common in places. This unit forms the lower part of the upper muddy Forest Marble and records waning energy after the main shell-bank phase, though sand and shell pulses still repeatedly crossed the area.

Bed WC16 — Torrens Bed 7, Upper Tile Bed With Spectacular Trace Fossils (2.5 m)

The highest Forest Marble unit at Watton Cliff is a clay bed with laminated sandstone lenses that split into tile-like slabs and preserve one of the richest trace-fossil assemblages in the Bathonian of southern England. Characteristic traces include Gyrochorte comosa, Imbrichnus wattonensis, Monocraterion, Neonereites, Pelecypodichnus, Planolites, Rhizocorallium, Teichichnus, Thalassinoides and Tibikoia. Rippled sandy laminae and the abundance of shallow-tier traces indicate a soft, intermittently colonized sea floor in shallow marginal-marine water. Hallam interpreted these beds as a slightly brackish coastal-lagoon or nearshore shelf setting influenced by freshwater influx from nearby rivers, and that interpretation remains broadly consistent with the sedimentology and trace-fossil suite.

Total Thickness Of Forest Marble Formation At Watton Cliff: About 25.3 Metres In The Torrens-Based Composite Log, With A Tiny Patch Of Cornbrash Formerly Present On The Cliff Top Showing That The Formation Was Essentially Complete

Depositional Environment

The Watton Cliff succession records the late Bathonian evolution of a shallow marine shelf in the Wessex Basin. The Frome Clay Formation represents prolonged offshore muddy deposition with only subordinate fine limestones and local shell concentrations, including the brachiopod-rich Wattonensis Beds at its base. The Boueti Bed marks a widespread late Bathonian transgressive or condensed shell-rich datum resting non-sequentially on the Frome Clay. Above it, the Forest Marble records increasingly mixed carbonate–siliciclastic sedimentation on a shallowing shelf: muddy lower beds with thin calcarenite bodies pass upward into a central shell-bank and calcirudite complex reworked by storms, followed by upper muddy and sandy beds with ripple lamination and a diverse trace-fossil suite. The Mammal Bed in particular shows that shell banks were breached and reworked during storms, allowing carbonized wood and reworked terrestrial vertebrate debris to be introduced into a dominantly marine setting.

Total Thickness Covered Here: More Than About 72 Metres Of Upper Bathonian Stratigraphy Are Represented At Watton Cliff, Although The Full Frome Clay Thickness Cannot Be Measured Exactly Because Of The Large Covered Gap In Its Lower To Middle Part

References

British Geological Survey Lexicon: Frome Clay Formation, Wattonensis Limestone Member, and Forest Marble Formation.
Cox, B.M. & Sumbler, M.G. (2002). Geological Conservation Review account for Watton Cliff in British Middle Jurassic Stratigraphy.
Dineley, D.L. & Metcalf, S.J. (1999). Geological Conservation Review account for Watton Cliff in Fossil Fishes of Great Britain.
Benton, M.J., Cook, E. & Hooker, J.J. (2005). Geological Conservation Review account for Watton Cliff in Mesozoic and Tertiary Fossil Mammals and Birds of Great Britain.
Arkell, W.J. (1933, 1947) on the Bathonian and Forest Marble successions of Dorset and regional correlation.
Torrens, H.S. (1969) on the Bathonian rocks of Watton Cliff and the bed numbering used here.
Holloway, S. (1981, 1983, 1985) on Forest Marble sedimentology, calcirudites, trace fossils and storm-breach channel interpretation at Watton Cliff.
Callomon, J.H. & Cope, J.C.W. (1995) on Bathonian ammonite correlation and the Quercinus Subzone assignment of the Frome Clay at Watton Cliff.
Freeman, E.F. (1976, 1979), Kermack et al. (1987, 1998), Evans (1992), Evans & Milner (1994), and Duffin (1985) on the mammal, amphibian, reptile and fish faunas of the Watton Cliff Mammal Bed.