Dumpton Gap has sandy beach, flint accumulations and a chalk wave-cut platform where patient searching can reveal echinoids, shells and sponges. Finds are not especially abundant, but the local flint bands give this coast considerable geological interest.
FIND FREQUENCY: ♦♦ – Scattered finds; flint accumulations and freshly scoured loose chalk repay careful inspection.
CHILDREN: ♦♦♦♦♦ – The main sandy bay is popular with families. Keep children away from cliffs, slippery reef and tidal corners.
ACCESS: ♦♦♦♦ – A slope and steps connect the clifftop with the promenade and beach. Check current street-parking signs.
TYPE: – Loose flints and detached chalk on the beach; fossils also occur in the protected cliff and platform.
DIRECTIONS
♦ The original approach is from the north-eastern end of Victoria Road beside King George VI Memorial Park. Park only where current signs permit.
♦ Take the public descent to the promenade, then turn left towards Dumpton Gap and the beach. Dumpton Gap Road provides another established approach to the bay.
♦ Check your return route before walking beyond the main beach: parts of this coast are cut off at high tide.
♦ Ref: 51.34902°N, 1.43967°E
FOSSIL HUNTING
At Dumpton Gap, start with the loose flint accumulations and the weathered surfaces of detached chalk exposed between the sandy patches. Echinoids and sponges occur in the flints, while chalk cobbles can reveal shells and fragile skeletal fragments. A recognisable surface is more useful than an unbroken lump: look slowly over each exposed face, without splitting blocks to search for a better specimen inside. Beach material is moved and abraded by the sea, so a loose find does not automatically retain its original bed position.
The chalk north of the gap is particularly informative. Faulting brings the lower Santonian succession down towards beach level, including beds with Cladoceramus undulatoplicatus and the conspicuous Bedwell’s Columnar Flint Band. Cladoceramus is a bivalve with strong, corrugated growth folds; broken shell and impressions are more realistic targets than an intact large shell. Cordiceramus cordiformis is another documented inoceramid in the associated fauna. Observe these shell-rich levels in place, then examine naturally detached material on the open beach rather than removing fossils from the platform.
Conulus albogalerus and heart-shaped Micraster are among the local echinoids. In a promising specimen, the plate pattern and narrow rows of paired pores distinguish the test from a similarly shaped flint. Some flints preserve only an internal cast, whereas chalk may still enclose a thin, easily damaged shell. Detached spines and pieces of regular echinoids are also recorded locally. Do not force chalk from a broken test merely to expose its outline: the visible fragment may be all that survives.
The basal Santonian fauna includes the brachiopods Gibbithyris ellipsoidalis and Orbirhynchia pisiformis. Look among the smaller loose chalk pieces as well as the conspicuous echinoid-bearing cobbles. A brachiopod’s two valves differ from those of a bivalve in their arrangement of symmetry, so a ribbed shell should not be called an inoceramid on texture alone. Barrel-shaped stem pieces of the crinoid Bourgueticrinus occur in this same documented assemblage. The original local account additionally records small corals, sponges and belemnites, and uses the historical echinoid name Sternotaxis; keep worn or incomplete examples at a broad identification unless diagnostic details survive.
Dumpton is the original locality of Labyrinthidoma dumptonense, a foraminifer, or single-celled organism, that built its chambered shell from sediment grains. “Large” here means large for a foraminifer: the original holotype is only 4 mm long. Its coiled early part and later series of chambers can be difficult to distinguish from an irregular chalk structure without magnification. The type material came from north of Dumpton Gap at the Columnar Flint level, although the precise original spot was not recorded. It is a specialist identification, not an expected beach find; retain a suspected example with its matrix and consult a specialist before preparation.
Use the Thanet Fossil Code for a small, selective collection of common loose fossils, avoiding digging and tools and reporting unusual finds. Keep away from fresh falls and cliff bases. Rising water cuts off parts of the Dumpton shore, so stop searching early enough to return by your known access.
A chronological record of geological research and significant milestones at Dumpton Gap.
1973 – An unusual giant foraminifer described
C. G. Adams, R. H. Knight and R. L. Hodgkinson described the new genus and species Labyrinthidoma dumptonensis, following Knight’s discovery in the Chalk of Dumpton Bay. Its intricate agglutinated test could not be fitted comfortably into the existing family scheme.
1986 – Marker beds placed in a modern lithostratigraphic scheme
Robinson’s logged Thanet succession clarified the relationships between the columnar flints, tabular flint markers and the overlying flint-poor chalk. At Dumpton the columnar band and the effects of faulting provide a particularly useful connection between visible rock layers and fossil zones.
1988 – Faulted coastal succession incorporated in Survey memoir
The Ramsgate and Dover memoir brought together the coastal sections, zonal mapping and structural interpretation, preserving the context needed to compare the Dumpton exposures with those farther north.
References
Adams, Knight & Hodgkinson (1973), An unusual agglutinating foraminifer from the Upper Cretaceous of England
Shephard-Thorn (1988), Geology of the country around Ramsgate and Dover, sheets 274 and 290
Thanet Coast Project, Fossil Code
Hubbard (2021), Thanet anticline’s shifting shorelines: Two millennia of change
Trevelyan (2021), The Smugglers Trail book review
Thanet Coast Project, Nature designations
Visit Thanet, Dumpton Gap
Young (1910), The Chalk Cliffs of Kent and Sussex, and the Tertiary beds of Herne Bay, Geology in the Field II, p.261
Mortimore, Wood & Gallois (2001), Thanet Coast, GCR 23
Hart (1995), Labyrinthidoma: an unusually large agglutinated foraminifer
GEOLOGY
Dumpton Gap is principally a section through the Seaford Chalk Formation, a soft white marine limestone containing repeated bands of nodular and sheet-like flint. The chalk accumulated as carbonate-rich sediment in the Late Cretaceous sea, whereas the flint formed within that sediment after deposition. The older name Broadstairs Chalk used in accounts of Thanet largely corresponds to this formation. Its alternating pale chalk and dark flint bands make individual levels much easier to follow than the almost flintless chalk farther around the north Thanet coast.
Faulting is important to what is exposed here: north of the gap it brings lower Santonian beds down towards the cliff foot. The strongly ribbed bivalve Cladoceramus undulatoplicatus occurs in this interval, with brachiopods and echinoids including Gibbithyris ellipsoidalis and Conulus albogalerus. Shell concentrations and changes in the fauna help geologists correlate beds that otherwise look very similar. Dumpton is also the original locality of Labyrinthidoma dumptonense, an unusually large single-celled foraminifer whose chambered test was built from sediment grains; its weathered remains can be mistaken for an inorganic structure.
Bedwell’s Columnar Flint Band is especially striking north of Dumpton Gap, where some nodules extend into large vertical columns or paramoudras. Columnar flints also occur in underlying bands, so a detached column cannot identify its original horizon by shape alone. Higher in the succession, Whitaker’s Three-inch Flint forms a contrasting sheet-like marker associated with silica replacement around a horizontal Thalassinoides burrow system. The intervening chalk and smaller flint bands preserve both shell concentrations and traces of life within the sediment.
The full cliff succession extends above the main foreshore beds. Barrois’ Sponge Bed caps the Seaford Chalk, and historical accounts describe a thin, fault-preserved cap of flint-poor Margate Chalk above it, belonging to the Newhaven Chalk Formation. That high-level cap is distinct from the lower material normally seen along the shore. Coastal defences have also changed the geological view: the published conservation account records the columnar band beside the seawall north of the gap, while protection of the cliff reduced natural erosion and obscured other exposures. Loose beach chalk and flint consequently provide only a partial, mixed sample of the original succession.
Detailed geology and stratigraphy of Dumpton Gap.
CHALK GROUP
The white rock is a marine limestone accumulated from carbonate-rich sediment during the Late Cretaceous. Flint formed within the sediment after deposition rather than being a layer of lava.
WHITE CHALK SUBGROUP
The local succession belongs to the flinty and flint-poor white chalks traditionally included in the Upper Chalk. Formation boundaries are based on rock character, whereas the zones used in many older accounts are based on fossils.
Seaford Chalk Formation
Soft white chalk contains repeated nodular and tabular flint layers. In the Thanet sections the older name Broadstairs Chalk largely corresponds to this formation; it is not an additional overlying unit. The flints provide conspicuous markers, but faulting can repeat or remove portions of a cliff section.
Basal Santonian fossil events
Faulting brings the lower Santonian interval down to the cliff foot north of Dumpton Gap. The section contains the characteristic ribbed inoceramid Cladoceramus undulatoplicatus, and the associated fauna includes Gibbithyris ellipsoidalis, Cordiceramus cordiformis and Conulus albogalerus. The corresponding named Pegwell Inoceramid Band has its type locality at Ramsgate.
Bedwell’s Columnar Flint Band
This marker comprises nodular flints with striking vertical extensions and locally large columnar paramoudras. North of Dumpton Gap the columns are particularly well developed, and additional examples occur in underlying flint bands. The band’s base coincides with a strong concentration of the ribbed bivalve Cladoceramus undulatoplicatus. The 2001 conservation account records that seawall construction north of Dumpton brought this band within reach for study at the top of the wall, while protecting the cliff reduced natural erosion and obscured other exposures.
Chalk between the Columnar and Three-inch flints
The Thanet composite section contains about 12 m of chalk between the two major flint markers, with 13 intervening flint bands, many comprising finger-like Zoophycos flints. This is a section-scale correlation interval, not a measured thickness for every individual bay. Several shell concentrations occur above the Columnar Flint, including a higher Cladoceramus/Platyceramus bed.
Whitaker’s Three-inch Flint Band
A conspicuous sheet-like flint contrasts with the separated nodules below. Its morphology reflects silica replacement around a horizontal Thalassinoides burrow system. It is a useful correlation marker with a historical name; its thickness varies.
The large agglutinating foraminifer
The Dumpton succession is important for Labyrinthidoma dumptonense, originally described as L. dumptonensis. The single-celled foraminifer built a complex chambered test from sediment grains. Its original discovery was at Dumpton Bay, and published records extend through much of the local Micraster coranguinum Zone. A weathered broken test can easily be mistaken for an inorganic structure.
Upper Seaford and Barrois’ Sponge Bed
The early coastal account traced the Three-inch Flint approximately 21 feet below Barrois’ Sponge Bed and recognised a thin higher chalk cap near Dumpton where small faults displaced the beds. The sponge marker therefore belongs in the full cliff succession, even though the lower, more readily studied foreshore interval is dominated by Seaford Chalk. Rowe’s Echinoid Bed is a separate, higher horizon.
Newhaven Chalk Formation
The local expression of this formation is the Margate Chalk Member. Its conspicuously flint-poor, marl-free appearance differs from the marl-rich succession at the formation’s Sussex type area.
Margate Chalk Member — local high-cliff cap
Small faults near Dumpton allowed a thin cap of chalk historically assigned to the broad Marsupites zone to survive at the cliff top. The old account explicitly described it as inaccessible. In modern lithostratigraphic terms the flint-poor chalk above Barrois’ Sponge Bed belongs to the Margate Chalk Member. The upper cap is distinct from the accessible lower foreshore exposures.
References
Adams, Knight & Hodgkinson (1973), An unusual agglutinating foraminifer from the Upper Cretaceous of England
Shephard-Thorn (1988), Geology of the country around Ramsgate and Dover, sheets 274 and 290
Young (1910), The Chalk Cliffs of Kent and Sussex, and the Tertiary beds of Herne Bay, Geology in the Field II, p.261
Mortimore, Wood & Gallois (2001), Thanet Coast, GCR 23
Hart (1995), Labyrinthidoma: an unusually large agglutinated foraminifer
BGS Lexicon, Margate Chalk Member
BGS Lexicon, Newhaven Chalk Formation
SAFETY
Tides can close the route beyond the main bay. Check times and sea conditions, work with a retreating tide and return before your exit is threatened.
Avoid cliffs and fresh falls. Algae-covered chalk and flints are slippery, and projecting corners can conceal the approaching sea.
EQUIPMENT
Wear sturdy footwear with a strong grip and carry a small bag, individual padding, labels and a hand lens. Bring suitable clothing, drinking water and a charged phone.
For a beachcombing visit, leave hammers, chisels and digging tools at home. Do not carry heavy rocks or overfill a bag on slippery ground.
CLEANING AND TREATING
Keep a label with the exact locality, date and, where known, the bed. Pack each chalk fossil separately with padding and support fragile shells with their surrounding matrix. Begin with a soft dry brush after gradual room-temperature drying; do not force chalk away from thin echinoid tests or crinoid plates. Avoid acids, bleach and routine varnish. Flint specimens are best retained as naturally weathered finds, rather than struck to chase a fossil into the nodule. Leave unusual or potentially important specimens unprepared for specialist assessment.
IDENTIFY YOUR FINDS
Need help identifying a fossil? Share clear photos, where you found it and its size with the community.
FURTHER READING
Hubbard (2021), Thanet anticline’s shifting shorelines: Two millennia of change
Trevelyan (2021), The Smugglers Trail book review
Mortimore, Wood & Gallois (2001), Thanet Coast, GCR 23
Adams, Knight & Hodgkinson (1973), An unusual agglutinating foraminifer from the Upper Cretaceous of England
Hart (1995), Labyrinthidoma: an unusually large agglutinated foraminifer
Shephard-Thorn (1988), Geology of the country around Ramsgate and Dover, sheets 274 and 290
Visit Thanet, Dumpton Gap
Thanet Coast Project, Fossil Code
Young (1910), The Chalk Cliffs of Kent and Sussex, and the Tertiary beds of Herne Bay, Geology in the Field II, p.261
ACCESS RIGHTS
Follow the Thanet Fossil Code: beachcomb for a small number of common loose fossils, leave the cliff and shore platform intact, and avoid digging or using tools. Keep away from cliff bases and freshly fallen material while further falls remain possible. Record the precise position of unusual finds and report them. Landowner permission remains necessary on privately owned parts of the shore. The voluntary collecting code and the site’s statutory nature-conservation designations are distinct.
It is important to follow our ‘Code of Conduct’ when collecting fossils or visiting any site. Please also read our ‘Terms and Conditions’.
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