The shore from Holywell towards Cow Gap exposes fossiliferous Cretaceous chalk and an important Cenomanian–Turonian boundary section. Ammonites, bivalves and brachiopods occur in the rocks, but fossils in loose blocks may have fallen from higher beds. Tides, slippery ground and unstable cliffs make careful planning essential.
FIND FREQUENCY: ♦♦♦♦♦ – Fossiliferous beds occur, but beach cover and preservation vary.
CHILDREN: ♦♦♦ – Rough, tidal ground is unsuitable for small children; keep everyone well clear of cliffs.
ACCESS: ♦♦♦ – Approach from Holywell using open signed access. The route towards Cow Gap is rough and tidal.
TYPE: Loose foreshore fossils and fallen blocks away from unstable cliffs.
DIRECTIONS
♦ Approach Holywell at the western end of Eastbourne seafront. Check current parking signs rather than assuming parking is permitted everywhere along the road.
♦ Use an open, signed promenade or beach entrance at Holywell. Routes include slopes and steps; not every path or staircase is necessarily open.
♦ The shore towards Cow Gap is rough and tidal. Check current access signs and conditions before continuing, and allow ample time to return.
♦ Ref: TV 60155 97165 – 50.75283°N, 0.26906°E
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FOSSIL HUNTING
The collecting ground for this guide is the foreshore from Holywell towards Cow Gap, rather than the whole Eastbourne–Beachy Head coast. Begin with naturally loose chalk pieces and flint pebbles between the groynes, then examine suitable material beyond the last groyne where conditions allow. This latter stretch has produced particularly good collections. Waves expose fossils on the surfaces of fallen blocks and sometimes release them completely; careful surface searching is therefore worthwhile before considering any preparation. Keep well clear of cliff bases and active fall debris.
Brachiopods and inoceramid bivalves are the most dependable groups to recognise. Look for the outline of paired shells, curved growth ridges and broken shell layers standing out against the chalk. Inoceramids can appear as broad, incomplete valves or concentrations of shell fragments rather than complete display specimens. Brachiopods are generally smaller and may retain a rounded or ribbed shell. Compare both sides of a loose specimen before naming it: a single weathered surface rarely provides all the features needed for a species identification.
The fossiliferous Holywell succession gives these ordinary shell finds a more specific context. The BGS memoir records Orbirhynchia, Concinnithyris and the echinoid Conulus subrotundus in the Eastbourne chalk below the Gun Gardens Main Marl. Compare the rounded, ribbed rhynchonellid shells of Orbirhynchia with the larger terebratulid form represented by Concinnithyris; preserve the beak and the meeting edge of the valves, which are useful identification features. At Holywell Pinnacles, the published succession includes bivalves of the Inoceramus pictus group and the ammonites Metoicoceras geslinianum and Euomphaloceras septemseriatum; higher Mytiloides and Watinoceras records help resolve the Cenomanian–Turonian transition. For Euomphaloceras, inspect the outside edge of the whorl as well as its flanks: ribs and rows of raised tubercles can survive on a fragment whose complete coil is missing. The original horizon remains important when separating these bed-specific faunas.
For ammonites, inspect naturally worn faces of light-grey chalk blocks for a curved whorl, repeated ribs or a circular section. Some show only part of the coil, so turn manageable loose pieces to see whether the pattern continues. Do not assume a visible crescent is a complete ammonite waiting to fall out, or strike close to an exposed shell. Preserve enough surrounding chalk to protect a promising specimen. Blocks fallen from different heights can lie together, and colour alone is insufficient to assign one to a formation or fossil zone.
Echinoids may be found already weathered free, while flint can preserve casts or moulds rather than an intact original shell. A regular five-part arrangement, paired pore rows or a recognisable body outline is more useful than a pebble simply resembling a sea urchin. Sponges, corals, shark teeth and fish scales are also recorded here. Treat the small vertebrate remains as occasional possibilities rather than routine finds, and use a hand lens on suspicious surface details without breaking up every piece of chalk.
Record the exact finding place, date and matrix, explicitly noting when a fossil was loose. Photograph unusual or associated remains before moving them and seek specialist advice before preparation. This shore belongs to the Seaford to Beachy Head SSSI: concentrate on loose material, leave in-situ beds and cliff faces undamaged, and follow current landowner guidance. Take only a modest selection that can be recorded and cared for; changing beach cover means the quality of a visit cannot be predicted from the site’s reputation alone.
A chronological record of geological research, fossil evidence and conservation milestones associated with Eastbourne.
1963 – Holywell Plenus Marls documented
R. P. S. Jefferies’s bed-by-bed study included Holywell in the eight-bed Plenus Marls framework. The completeness of the section later made it an important replacement reference after the original Merstham exposure was lost.
1981 – A boundary ammonite described
C. W. Wright and W. J. Kennedy published a Holywell ammonite identified as Watinoceras cf. amudariense. Its position within the Meads Marls helped locate the beginning of the Turonian in a succession whose lithological boundaries do not all match stage boundaries.
1986 – Holywell marker beds formalised
Rory Mortimore’s Sussex Chalk study established the local framework of Holywell beds and marl markers. Subsequent revisions retained Holywell as a type locality while changing some formation limits.
1996 – Boundary correlations refined
Andrew Gale’s work refined the ammonite and inoceramid succession through the Meads Marls, distinguishing terminal Cenomanian assemblages from the lowest Turonian faunas.
1999 – European reference section proposed
A study led by Christopher Paul integrated fossil and geochemical records from Holywell Steps and Gun Gardens to propose an Eastbourne reference section for the Cenomanian–Turonian boundary. The published section is a composite of these separate exposures.
15 November 1999 – Geological conservation interests recognised
The current Seaford to Beachy Head SSSI notification recorded the coast’s geological importance, including its Chalk cliffs, Greensand reef and the fossil soils and molluscan record at Cow Gap.
2001 – Holywell becomes part of the revised Chalk framework
The revised national Chalk classification placed the Plenus Marls within the Holywell Nodular Chalk Formation and made its base the base of the White Chalk Subgroup, clarifying how the classic Holywell section fits the modern hierarchy.
2009–2010 – Holywell Pinnacle sampled in detail
Two field campaigns collected 84 samples through 33.8 m of the Holywell Pinnacle succession, covering upper Cenomanian chalk, the Plenus Marls and the lower Turonian interval. The bed-by-bed work supplied a distinct local microfossil record rather than borrowing a section from Gun Gardens.
2011 – The nannofossil record analysed
Christian Linnert, Jörg Mutterlose and Rory Mortimore published a quantitative study of the Holywell samples. Changes in microscopic calcareous plankton, including ten first or last occurrence levels, added detailed evidence about environmental change across the Cenomanian–Turonian interval.
GEOLOGY
Holywell and Cow Gap expose different parts of a Cretaceous succession, with landslipping displacing older beds around Cow Gap. Albian Gault and Upper Greensand lie below the Chalk; Head Ledge belongs to Upper Greensand rather than the Plenus Marls.
At Cow Gap the contrast between the older rocks is particularly important. Dark Gault clay forms a weak substrate beneath green glauconitic sand and paler calcareous sandstone of the Upper Greensand. Hard sandstone bands and rounded cemented masses interrupt the softer material, and burrows occur at both the Gault–Upper Greensand contact and the younger contact beneath the Chalk. Movement within the weak clay has rotated and displaced the overlying rocks, so repeated blocks on the shore do not represent a simple extra thickness of sediment.
The Chalk itself is a marine limestone largely formed from microscopic calcareous plankton. At Holywell its appearance changes from pale, blocky Zig Zag Chalk into the grey-green marl and pale chalk alternations of the Plenus Marls, then into harder nodular chalk in the Melbourn Rock interval. The relatively impermeable marl contact below the latter helps explain the position of the Holywell spring. Higher beds contain conspicuous marl seams and whole or broken Mytiloides shells: the white cliff is therefore a succession of contrasting sediments and fossil horizons, not one uniform rock.
Meads Marl 1 marks the top of the Melbourn Rock Member in the modern BGS interpretation; the succeeding Meads and higher marl-bearing beds remain within Holywell Nodular Chalk. Historical papers give the Melbourn interval different limits, and published Plenus thicknesses also differ between about 6 m in the GCR account and up to 3 m in the BGS café section. These figures describe different published sections and limits. Above the slipped ground around Cow Gap, much younger coombe rock, chalk mud, fossil soils and hillwash record later slope and valley development rather than Cretaceous marine deposition.
West Melbury Marly Chalk and Zig Zag Chalk belong to the Grey Chalk Subgroup. White Chalk begins at the base of the Plenus Marls within the Holywell Nodular Chalk Formation, below the Cenomanian–Turonian stage boundary. Marl seams, nodular chalk and fossil changes provide finer markers.
A Holywell study sampled 33.8 m using Beds 79–136. These sample numbers are distinct from the eight standard Plenus beds, and the total is a sampled interval rather than formation thickness. The Foyle Track’s higher New Pit–Lewes exposure is separate from the shore section; its historical record does not establish current access.
Detailed geology and stratigraphy of Eastbourne.
The shore between Holywell and Cow Gap combines a classic Cenomanian–Turonian boundary section with older beds exposed in landslipped ground farther south. The cliff, the offshore Greensand reef and the separate Foyle Track exposures must be distinguished: a fossil found loose on the beach does not automatically identify the bed beneath it.
Holywell Pinnacle numbered log. A later bed-by-bed study sampled a 33.8 m section at Holywell Pinnacle, using its own numbers 79–136. These sample-bed numbers are distinct from Jefferies’s eight Plenus beds and Mortimore’s marl names. The paper’s older formation and member names are correlated here with the modern BGS units; its measured total is a sampled interval, not a formation thickness.
SELBORNE GROUP
Albian rocks beneath the Chalk are exposed locally on the shore and in displaced blocks around Cow Gap. Their outcrop is interrupted and repeated by landslipping.
Gault Formation
Dark clay and mudstone occur intermittently at the base of the slipped succession. Failure within these weaker beds has allowed the overlying Upper Greensand and Chalk to rotate seawards. No complete local formation thickness is exposed.
Gault–Upper Greensand contact. The contact is strongly burrowed. It belongs to the Albian succession and should not be confused with the younger, separately burrowed boundary at the base of the Chalk.
Upper Greensand Formation
Glauconitic sandstone forms the offshore reefs and shore-platform ledges, including Head Ledge at Cow Gap. These are displaced outcrops associated with the toes of landslips, not evidence of a simple uninterrupted vertical section along the beach.
Basal green sand and overlying calcareous sandstones. Dark green, glauconitic sand passes upwards into paler, slightly micaceous calcareous sandstone. Local hard calcareous bands and doggers interrupt the sandstone; the upper part is bedded and extensively bioturbated. Fossils are sparse, although ammonites, nautiloids, bivalves and echinoids have been recorded from this local Upper Greensand.
Upper Greensand–Glauconitic Marl contact. Burrows penetrate the top of the sandstone beneath the glauconitic basal Chalk. Thalassinoides is recorded at the contact; small phosphatic nodules occur in the overlying marl.
CHALK GROUP
The Chalk is marine limestone, largely built from microscopic calcareous plankton. The modern subdivision used below separates the Grey Chalk from the overlying White Chalk; these are lithostratigraphic units, not simple colour labels.
GREY CHALK SUBGROUP
The West Melbury Marly Chalk and Zig Zag Chalk belong to the Grey Chalk Subgroup. The Plenus Marls are excluded from this subgroup in the current BGS framework.
West Melbury Marly Chalk Formation
At the Cow Gap end, alternating marl and chalk overlie the Glauconitic Marl. These lower Chalk beds belong to the Cenomanian and are exposed in the low slipped cliffs, rather than throughout the Holywell cliff.
Glauconitic Marl Member
The basal Chalk is a glauconitic marl with phosphatic nodules and fossiliferous concretions, above the burrowed Upper Greensand contact. Sponges, inoceramid bivalves and ammonites are recorded around Cow Gap. The detailed ammonite-bearing pebble-bed log farther west at Falling Sands is not transferred to this exposure.
Zig Zag Chalk Formation
The top of this formation is exposed locally below the Plenus Marls south of Holywell. It consists of pale blocky chalk with marl interbeds. The Plenus Marls themselves belong to the overlying Holywell Nodular Chalk Formation.
Upper Zig Zag Chalk, sampled Beds 79–99. In the Holywell study, the pre-Plenus succession consists of grey marly limestones separated by thin marl layers. These beds lie below the prominent marl used as Bed 100, the base of the Plenus Marls; the paper does not provide separate descriptive prose for every individual bed in this lower numbered series.
WHITE CHALK SUBGROUP
The subgroup begins at the base of the Plenus Marls, below the Cenomanian–Turonian stage boundary. Consequently the lowest White Chalk here is still Cenomanian.
Holywell Nodular Chalk Formation
Holywell is a type locality for this formation. The cliff and Pinnacle expose white chalk with nodular beds, conspicuous marl seams and thinner wispy marls. The formation includes the Plenus Marls, the Melbourn Rock interval and the succeeding shell-bearing chalk.
Plenus Marls Member
Grey-green marls alternating with paler chalk form the conspicuous basal unit. Eight numbered beds are recognised in the regional standard, and Holywell is an important reference section. Published thicknesses for Holywell differ: the GCR describes about 6 m, whereas the BGS Lexicon quotes up to 3 m at the café section; these measurements should not be treated as interchangeable.
Plenus basal marl, Bed 100. The conspicuous lowest marl is the local sampling datum. The last recorded Corollithion kennedyi occurs 0.50 m above its base in the study. That number is height above a stratigraphic datum, not marl thickness.
Second thick marl, Bed 102. The next major lower Plenus marl is Bed 102. The last Cretarhabdus striatus was recorded 4.52 m above the Plenus base, followed by the first Rotelapillus biarcus 0.25 m higher. Their local ordering differs from the expected zonal succession, an important reason not to treat every global microfossil datum as perfectly synchronous.
Upper Plenus Beds 103–111. Marly limestone and marl alternate in the upper part of the member. One especially thin marl, Bed 107, is only 0.02 m thick and was not sampled in the nannofossil campaign. The complete study interval assigned to the Plenus Marls is Beds 100–111; it is not an additional twelve-bed replacement for Jefferies’s scheme.
Melbourn Rock Member
The harder, nodular chalk above the Plenus Marls is the local Melbourn Rock interval. Its expression in the expanded Sussex succession differs from the very hard rock at the Cambridgeshire type area. At Holywell the spring emerges along the relatively impermeable marl contact below it. Older papers and alternative schemes use different limits for this interval.
Melbourn Rock fossil horizons. Inoceramid bivalves related to Inoceramus pictus occur at Holywell Pinnacles up to the bed below Meads Marl 1. Metoicoceras geslinianum and Euomphaloceras septemseriatum extend into the chalk above the Plenus Marls, reaching couplet E 13 in the published Holywell scheme. Fossil zones therefore do not coincide exactly with the lithological boundary.
Holywell Nodular Chalk Formation
Above the Melbourn Rock Member, whose top is marked by Meads Marl 1, the succession continues within the Holywell Nodular Chalk Formation.
Meads Marls 1–6. Six closely spaced marl markers subdivide the chalk above the Melbourn Rock. Meads Marl 1 marks the top of the Melbourn Rock in Mortimore’s Sussex scheme. Marls 2 and 3 lie below the critical boundary interval; Marl 4 is the last named marl below the entry of abundant Mytiloides, and Marls 5 and 6 continue the succession above it. The boundary interval is within the formation, not at its base.
Meads Marl 4–5 boundary interval. The terminal Cenomanian ammonites Neocardioceras juddii and Thomelites serotinus disappear just above Meads Marl 4 in the published Eastbourne/Holywell framework. Abundant Mytiloides and records of Watinoceras identify the lowest Turonian interval between Marls 4 and 5. The earlier Holywell specimen published as Watinoceras cf. amudariense was important in recognising this boundary.
Post-Plenus sampled Beds 112–125. Nodular pale limestones follow the marls. The author’s Ballard Cliff Member includes this interval and the Meads Marls, so its limits must not be equated automatically with the more restricted BGS Melbourn Rock Member.
Meads marl sample-bed correspondence. The six marl seams are Beds 115, 117, 119, 121, 123 and 125 in the Holywell sampled log. The paper also uses three paired Meads units: its second pair ends with Bed 121. The Cenomanian–Turonian boundary is placed 0.10 m above that marl, within Bed 122, consistent with the critical interval above the fourth individual marl.
Higher sampled Holywell marls. Above Bed 125, fine-grained pale limestone alternates with thin marls. Beds 127, 129, 131, 133 and 135 identify five sampled marl seams within this higher interval. These bed numbers are retained rather than assigned an unsupported one-to-one match with every marl name in earlier schemes.
Nannofossil succession above the Plenus Marls. Measured from the base of the Plenus Marls, the study recorded the last Lithraphidites acutus at 7.08 m, first Eprolithus octopetalus at 7.99 m, last Axopodorhabdus albianus at 8.49 m and first Quadrum intermedium at 9.41 m. These are microfossil occurrence levels in the sampled section, not bed thicknesses.
Nannofossil events near the stage boundary. The first recorded Quadrum gartneri lies at 10.29 m above the Plenus base, the last Helenea chiastia at 10.46 m and the last Rhagodiscus asper at 11.46 m. The reversed local order of some zonal markers was explicitly discussed in the study; it does not demonstrate a missing package of rock by itself.
Higher Holywell marl and shell-detrital beds. Above the Meads Marls, further named Holywell and Gun Gardens marls divide massive to nodular chalk. In the Sussex reference succession, lower smoother chalk gives way to beds rich in whole and broken Mytiloides shells. These marker names link Holywell to other sections, but the old regional Ranscombe Member does not supply a complete local numbered log; its upper Holywell Beds are now part of New Pit Chalk.
New Pit Chalk Formation
On the separate Foyle Track above the shore, the upper New Pit Chalk and its transition into Lewes Nodular Chalk are recorded. This heavily faulted track exposure is distinct from the Holywell boundary section at beach level.
Glynde marl interval at Foyle Track. The track exposes the contact interval between smooth New Pit Chalk and nodular, iron-stained basal Lewes Chalk, with tubular or finger-shaped flints. Beds above and below the Glynde marl are reported to contain abundant inoceramid bivalves identified in the local survey as Inoceramus cuvieri. Faulting prevents treating this as an undisturbed continuation of the shore log.
Lewes Nodular Chalk Formation
Nodular chalk, local hardgrounds and flint bands occur in the upper Foyle Track exposure. They do not justify assigning the whole Lewes succession or its farther-west named sponge beds to the Holywell beach.
Quaternary deposits and landslipping. At Whitebread Hole and Cow Gap, younger deposits rest on an irregular Chalk surface. Coombe rock occupies hollows; bedded chalk muds and pale fossil soils overlie it, followed by postglacial chalky hillwash. These deposits include late-glacial and Holocene molluscan faunas and have been displaced by landslipping. They are separate from the Cretaceous marine succession.
References
BGS, A stratigraphical framework for the Lower Cretaceous of England
Sussex Geodiversity Partnership, Cow Gap, 2011 field survey
May (2003), Beachy Head–Seaford Head, Coastal Geomorphology of Great Britain
Mortimore, Wood and Gallois (2001), British Upper Cretaceous Stratigraphy; Southerham Grey Pit account, Beachy Head comparison, figures 3.111–3.113
Hopson (2005), A stratigraphical framework for the Upper Cretaceous Chalk of England and Scotland, BGS RR/05/01
Sussex Geodiversity Partnership, Holywell Sections and Foyle Track, 2011 field survey
BGS Lexicon, HCK
Mortimore, Wood and Gallois (2001), British Upper Cretaceous Stratigraphy, Southern Province chapter
Linnert, Mutterlose and Mortimore (2011), Calcareous nannofossils from Eastbourne, PALAIOS 26, 298–313; author-posted full article text, p.299 and figures 2, 5
Lake, Young, Wood and Mortimore (1987), Geology of the country around Lewes; Eastbourne comparison sections
Natural England, Seaford to Beachy Head SSSI citation, current notification 15 November 1999
SAFETY
Visit only with a suitable tide window and return before the incoming sea restricts your route. The headlands and boulder-strewn shore can cut off an apparently short walk.
Stay well away from cliff bases, overhangs and active falls. Wet chalk and seaweed are slippery; a helmet does not make working beneath an unstable cliff safe. Follow current barriers and signs.
EQUIPMENT
Take sturdy footwear with good grip, tide information, a hand lens, a camera, wrapping material and rigid specimen boxes. Keep the load manageable for the rocky shore.
Loose chalk fossils can be fragile. A soft brush and careful packing are more useful than levering specimens from the platform; do not hammer cliffs or in-situ features.
CLEANING AND TREATING
Allow wet specimens to dry slowly at room temperature, then begin with gentle dry brushing. Support thin shells and exposed echinoid tests rather than scrubbing them or trying to force away attached chalk.
Avoid acids, bleach and routine varnish. Hard chalk or flint preparation can damage the fossil as easily as the matrix; stop if the surface is flaking and seek specialist advice. Keep potentially important specimens unprepared.
IDENTIFY YOUR FINDS
Need help identifying a fossil? Share clear photos, where you found it and its size with the community.
FURTHER READING
Linnert, Mutterlose and Mortimore (2011), Calcareous nannofossils from Eastbourne (southeastern England) and the paleoceanography of the Cenomanian–Turonian boundary interval, PALAIOS 26, 298–313 Author-posted article text; see p. 299 and figures 2 and 5.
Linnert, Mutterlose and Mortimore (2011), Calcareous nannofossils from Eastbourne, PALAIOS 26, 298–313 This publisher-hosted file contains the abstract and bibliographic record.
Sussex Geodiversity Partnership, Holywell Sections and Foyle Track, 2011 field survey
Mortimore, Wood and Gallois (2001), Southerham Grey Pit and the Beachy Head comparison, British Upper Cretaceous Stratigraphy, figures 3.111–3.113
May (2003), Beachy Head–Seaford Head, Coastal Geomorphology of Great Britain
Mortimore, Wood and Gallois (2001), British Upper Cretaceous Stratigraphy, Southern Province chapter
Lake, Young, Wood and Mortimore (1987), Geology of the country around Lewes
Visit Eastbourne: Beaches
ACCESS RIGHTS
Follow current landowner and council access guidance. Protected geological status is not permission to excavate or enter a closed area. Keep collecting low-impact and limited to genuinely loose material where permitted; seek permission for intrusive sampling and leave recorded features intact.
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