Allhallows-on-Sea
Region: Kent
Nearest Town: Allhallows-on-Sea
Geological Age: Ypresian • Eocene • Palaeogene • Cenozoic
Site Type: Foreshore
About the Site
Allhallows-on-Sea is a London Clay fossil locality on the southern side of the Thames Estuary, at the northern edge of the Hoo Peninsula in Kent.
The LBPS locality represents the foreshore adjoining Allhallows Holiday Park, particularly the upper shore where patches of London Clay, shingle and naturally released nodules can occasionally be exposed.
Unlike the large London Clay cliffs of the Isle of Sheppey, there is no substantial fossil cliff here. The clay is exposed intermittently on the foreshore and may be almost completely hidden by mud and modern sediment during unfavourable conditions.
The site is particularly associated with fossil crustaceans preserved in nodules. Shark and other vertebrate remains are much less conspicuous, making Allhallows a locality where careful searching is more useful than expecting large numbers of obvious fossils.
Site Images
Geology & Stratigraphy
The fossil-bearing bedrock is the London Clay Formation, part of the Thames Group and of Ypresian age.
London Clay underlies much of this part of the Hoo Peninsula, although younger river, estuarine and Pleistocene deposits occur locally above it inland. Geological investigations around Allhallows confirm London Clay as the underlying Eocene bedrock.
At the collecting locality itself the London Clay is exposed only intermittently across the tidal foreshore. Modern mud, silt and beach material can obscure large areas, so there is no continuous section through which the detailed stratigraphy can easily be followed.
The precise position of the exposure within the traditional London Clay subdivisions is uncertain. Some collecting literature assigns the site to Division D, whereas King’s detailed London Clay work discusses palaeontological evidence from Allhallows as probably belonging to Division C.
These lettered divisions are historical stratigraphic terminology rather than the modern formal Geological Unit used for the locality. Until the precise correlation of the active foreshore exposure is better established, London Clay Formation is the most reliable formal assignment.
Palaeoenvironment & Palaeoecology
The London Clay at Allhallows was deposited in a marine environment within the Early Eocene London Basin.
Fine clay and silt settled on the seabed while fish, sharks, crustaceans and other marine organisms occupied the surrounding waters and bottom sediments.
The fossil crustaceans indicate a benthic marine community living on or close to the muddy seabed. Organic remains and material from nearby land could also enter the marine basin, as occurs elsewhere in the London Clay.
The present Thames Estuary is much younger than the fossil-bearing deposit. Modern tidal processes now expose and redistribute fossils from sediments that accumulated around 50 million years ago.
Fossil Preservation & Taphonomy
One of the most characteristic forms of preservation at Allhallows is fossil material contained within phosphatic and septarian nodules.
Crab and lobster remains may occur inside these nodules as carapaces, claws or other hard skeletal parts. Individual fragments are considerably more common than exceptional complete specimens.
Small fossils can also weather completely free from the London Clay and become mixed with shingle and other resistant material on the upper foreshore.
The modern Thames repeatedly moves loose material. Nodules and fossils may therefore have travelled after being released from the clay.
A loose specimen should not automatically be assigned to the exact patch of bedrock underneath the point where it was found.
The intermittent exposure also means that the productive surface can change markedly between visits as fresh sediment covers or uncovers the London Clay.
Collecting Guidance
Visit around low tide, when the largest amount of upper foreshore is exposed.
The most productive conditions occur when tidal action has removed some of the mud and silt normally covering the London Clay and associated shingle.
Search slowly around patches of firm exposed clay and amongst washed material where harder nodules have accumulated.
Conditions can change significantly between visits. A productive patch may later disappear beneath fresh estuarine sediment.
Avoid walking farther onto the mudflat simply because the tide has retreated.
Useful equipment includes:
- waterproof boots with good grip
- gloves
- knee pads
- a hand lens
- small specimen boxes or bags
- labels or a notebook
- a phone for tide information
A geological hammer is not required for normal collecting.
What to Look For
Concentrate on small nodules and patches of washed shingle on the firmer upper foreshore.
Crustacean-bearing nodules are the characteristic find. Look for pieces of organised shell, carapace texture, claws or other structures breaking through the surface of a nodule.
Some nodules are completely unfossiliferous, so a rounded or unusual shape alone is not evidence of a fossil.
Small shark or fish teeth can occur, although they are much less conspicuous than at some other London Clay sites. Look for enamel surfaces and a genuine tooth crown rather than simply pointed dark stones.
Fragments of other marine fossils may also occur amongst naturally weathered material.
Use Fossils at this Site for the individual species recorded from Allhallows rather than maintaining a manual species list here.
Fossils at this Site
Explore fossils recorded from this site, see how to recognise them and, where enough LBPS records exist, what collectors are actually finding.
What collectors are finding
Typical examples from this site
Different anatomical parts or preservation styles can look very different. Choose an example to view it larger.
About this information
Fossil occurrences come from reviewed LBPS records. Encounter frequency and abundance use eligible collecting sessions where all finds were recorded. Preservation rarity uses the condition recorded at the time of collecting. Identification photographs may come from dedicated Fossil Examples or linked public LBPS Specimens; neither influences rarity or frequency calculations.
Visitor & Access Information
General Location
Allhallows-on-Sea, on the northern coast of the Hoo Peninsula in Kent, overlooking the Thames Estuary.
The LBPS locality is the fossil-bearing upper foreshore adjoining the Allhallows holiday park.
It should not be interpreted as the entire Allhallows–Grain coastline.
Directions
Travel to Allhallows-on-Sea on the Hoo Peninsula.
Use the established public footpath/coastal route through or around the holiday park area towards the Thames shoreline.
Once at the waterfront, follow the seawall and public coastal route to reach the fossil-bearing upper foreshore.
The London Clay is not continuously exposed, so look for darker clay patches, shingle and nodules uncovered between modern mud and beach sediment.
Parking
There is no dedicated public fossil-site car park that LBPS can currently confirm independently of the holiday park.
Use lawful public parking in Allhallows and approach the coast on foot.
Parking within the holiday park should only be used where current visitor arrangements explicitly allow it. Do not rely on older collecting-guide information about paid access or parking without checking locally.
Terrain
The approach follows surfaced paths, public footpaths and the seawall.
The collecting area itself consists of:
- muddy upper foreshore
- shingle
- patches of exposed London Clay
- algae-covered stones and structures
- extensive softer mud towards the lower shore
There are no substantial fossil cliffs.
The lower intertidal mud is considerably less suitable for walking than the firmer upper shore.
Access, Permissions & Responsible Collecting
Use the established public footpaths and coast path to reach the shoreline.
There are public rights of way associated with the Allhallows Holiday Park area, but the holiday park itself remains private commercial property. Do not assume that visitor access to the coast provides unrestricted access to caravan areas, facilities or private parking. Medway planning records confirm established public rights of way running through the park area towards the river.
Collect from naturally released loose material on the accessible upper foreshore.
There is no need to excavate the London Clay. Avoid digging into exposed bedrock or disturbing saltmarsh vegetation.
Much of the surrounding Thames Estuary is internationally important for birds, so keep away from feeding and roosting flocks and follow any seasonal signs or restrictions.
Safety & Legal Information
Safety Information
The main hazard is soft intertidal mud.
Stay on the firmer upper foreshore. The lower Thames mudflats are extensive and can become deep enough to trap footwear or make movement difficult.
Official coastal-access assessments specifically identify extensive mudflat and saltmarsh along this coastline as unsuitable for normal public access.
Check tide times before collecting.
Algae-covered steps, seawalls and stones can be slippery.
The Thames is a major working estuary, so remain aware of rapidly changing water levels and avoid entering the water.
SSSI / Legal Restrictions
The wider Allhallows coastline borders the South Thames Estuary and Marshes SSSI and the internationally protected Thames Estuary and Marshes SPA/Ramsar area, which are particularly important for their wetland habitats and bird populations.
These protections should not be described as if Allhallows were designated specifically as a geological fossil SSSI.
Public access also does not mean that every part of the mudflat and saltmarsh can be entered. Some intertidal areas are formally excluded from coastal access because they are unsuitable for public use.
Keep fossil collecting to small amounts of naturally released material on the accessible upper foreshore.
Do not damage saltmarsh, disturb birds or carry out substantial excavation.