The tidal foreshore at Harwich exposes the Harwich Stone Band, a hard, ash-bearing horizon formed in an early Eocene sea. Loose beach material can yield shark and fish teeth, fossil wood and seeds. The most useful patches change as waves move the shingle and sand, so careful searching matters more than covering a large area.
FIND FREQUENCY: ♦♦♦♦ – Teeth and plant remains occur in loose foreshore debris, but beach cover strongly affects finds.
CHILDREN: ♦♦♦♦ – Supervise closely on firm accessible shore; avoid mud, slippery rock and sharp debris.
ACCESS: ♦♦♦ – Reach the shore from Harwich Green and the Low Lighthouse using signed access. Check current parking charges.
TYPE: Tidal foreshore with shingle, clayey sediment and hard stone-band exposures.
DIRECTIONS
♦ Follow the A120 towards Harwich and continue to Harbour Crescent by Harwich Green. The original parking approach is along Harbour Crescent; use only permitted spaces and check current restrictions and charges.
♦ Alternatively, Wellington Road car park, CO12 3DL, is a council parking option. Check its current charges and conditions before travelling.
♦ Walk towards the white brick Low Lighthouse, which houses Harwich Maritime Museum, and use public beach access where open. The geological foreshore described here extends south towards Beacon Cliff. This is separate from the iron lighthouses at Dovercourt.
♦ Plan the visit around the tides, staying on firm accessible shore and clear of harbour operations.
♦ What3Words collecting area: ///hazel.reputable.visa
FOSSIL HUNTING
Look closely through loose shingle and pyrite-rich debris rather than breaking the hard stone band. Small teeth, fruits, seeds and fragments of wood can be concentrated by wave action, but sand can also bury a productive patch. Inspect small areas carefully and avoid pushing farther onto soft mud.
The published plant assemblage includes Platycarya richardsonii and Vitis magnisperma; much of the material is pyritised. These are plant reproductive structures, not a general collection of pine cones. Fossil wood and microscopic marine organisms add to the scientific interest of the site.
Keep the matrix and location details with unusual finds. The wider Harwich area has a long history of dredged and collected material, but an offshore or broadly labelled specimen should not automatically be assigned to this beach or a particular exposed bed. Fragile associated remains are best left unprepared for specialist advice.
A chronological record of fossil discoveries and geological research at Harwich.
1704 – An early geological account
Samuel Dale described Harwich Cliff, long before the promenade and sea defences obscured the natural section.
1730 – A fuller description
Dale’s later account expanded the published record of the Harwich exposure and its fossils.
1918 – Stone band documented
William Whitaker recorded the distinctive resistant band at Harwich, a conspicuous feature of the local geology.
1951 – The section revisited
Davis and Elliott added to the description of the Harwich deposits before the volcanic significance of the stone band was fully recognised.
1971 – Evidence of Eocene volcanism
Elliott demonstrated the volcanic ash component of the Harwich Stone Band, establishing its importance for understanding early Eocene ash deposition in the London Basin.
1972 – Fossil wood investigated
Brett described fossil plane-tree wood from Harwich and discussed possible root material, adding anatomical evidence to the locality’s plant record.
1985 – Magnetic evidence examined
Townsend and Hailwood investigated the stone band and underlying muds, recording reversed magnetisation useful in interpreting the early Eocene succession.
1994 – Modern formation terminology
The ash-bearing basal succession was placed within the newly defined Harwich Formation, separating it from the overlying London Clay Formation.
GEOLOGY
The Harwich Formation, within the Thames Group, was formerly included in the basal London Clay. At Harwich its Wrabness Member contains fine marine sediments and the distinctive Harwich Stone Band, which incorporates material from explosive volcanic eruptions during the early Eocene.
The stone band is a carbonate-cemented, ash-bearing layer rather than a slab of pure volcanic ash. It rests on softer fossiliferous mud and is overlain by further fine sediment. Volcanic particles, burrows and microfossils reveal both the arrival of ash and its incorporation into a living marine environment.
Sea defences now obscure the old cliff line, leaving the tidal foreshore as the principal exposure. Historic descriptions record about seven metres of the succession, but this is not a guarantee of continuous visibility. The many higher ash seams documented at Wrabness must not be imported into this much more limited Harwich section.
Detailed geology and stratigraphy of Harwich.
This account concerns the eastern Harwich foreshore between Beacon Cliff and Harwich Green. It does not import the higher ash succession exposed at Wrabness.
THAMES GROUP
Harwich Formation
Wrabness Member
These early Eocene strata were historically described as the lowest London Clay. Modern terminology separates them as the Harwich Formation. The old natural cliff has been protected by the promenade, and the surviving geological exposures lie on the tidal foreshore.
Muds below the Harwich Stone Band
Soft marine clayey silts underlie the hard band. Published records include fish teeth, plant remains, diatoms such as Coscinodiscus and the foraminifer Astrorhiza, together with microfossils reworked from the Chalk. Modern waves can redistribute fossils, so a loose foreshore specimen does not establish its original horizon.
Harwich Stone Band — approximately 0.20 m locally
The exact-site GCR account describes a strongly lithified, broadly tabular band resting sharply on soft mud. Volcanic glass shards, some pumice-like, occur with feldspar and rock fragments; ash content varies laterally. The band is therefore an ash-bearing cemented sediment, not a uniform sheet of pure volcanic ash. Sparse molluscs, microcoprolites, diatoms, pyritised radiolarians and evidence of burrowing have been recorded. The BGS’s approximately 0.25 m general thickness is slightly greater than the local GCR estimate.
Muds above the Harwich Stone Band
Higher soft muds contain woody material and a microfossil assemblage comparable to that below the band. These beds have often been poorly exposed beneath beach sediment. There is insufficient exact-site evidence to present them as a finely numbered succession.
Elliott’s 1971 account described approximately 7 m of the lower succession, but the formation’s basal contact was not exposed. Dredged material from an older “basement bed” must not be shown as an accessible foreshore layer. The Stone Band is a valuable marker for comparing exposures elsewhere in eastern Essex and southern Suffolk.
The flora includes pyritised Platycarya richardsonii and Vitis magnisperma, with fossil plane-tree wood also reported. These remains provide evidence of vegetation on land bordering the early Eocene sea. Because the plant-bearing sediments are associated with correlatable ash bands, they are especially useful for placing the flora within the early Thames Group succession.
References
GCR: Harwich geology
GCR: Harwich fossil plants
BGS: Harwich Stone Band
BGS: Wrabness Member
SAFETY
Check the tide and keep a straightforward return route to signed access. Algae-covered stone can be very slippery, while fine mud may be deep even close to a hard exposure. Do not venture towards harbour navigation areas.
Watch for broken glass, metal and other sharp debris before kneeling or putting a hand into the shingle. Supervise children closely and do not assume the whole foreshore is safe because it lies beside a promenade.
EQUIPMENT
A hand lens, sturdy non-slip footwear, a soft brush, tide information and small padded boxes are sufficient for surface searching. Record unusual finds with a photograph and location. Hammering the stone band is unnecessary and damages the geological exposure.
CLEANING AND TREATING
Keep delicate fruits, seeds and wood supported in their matrix. Do not soak pyritic material, acid-clean the stone band or coat specimens with household varnish. Robust loose teeth can be gently brushed.
Fragile wet material needs conservation advice before drying. Once safely dried, store pyritic specimens in dry, stable conditions and inspect them for cracking or powdery decay. Scientifically important material should remain unprepared until reviewed.
IDENTIFY YOUR FINDS
Need help identifying a fossil? Share clear photos, where you found it and its size with the community.
FURTHER READING
Deposits: The geology of Essex (regional background)
Geological Conservation Review: Harwich geology
Geological Conservation Review: Harwich fossil plants
BGS Lexicon: Harwich Stone Band
Tendring Council: Wellington Road parking
ACCESS RIGHTS
Harwich Foreshore is a SSSI. Use public shore access and follow local notices; access is not permission to excavate the beds or remove the intact stone band. Limit ordinary searching to loose material and seek the appropriate permission for any scientific sampling.
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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