West Weare on Portland exposes Kimmeridge Clay and the Portland succession among landslipped ground and old quarry waste. Shells and ammonite fragments are recorded, but mixed blocks, slippery clay and difficult terrain make provenance and a cautious, permission-led approach especially important.
FIND FREQUENCY: ♦♦♦ – Shells and ammonite fragments are recorded; complete ammonites and vertebrate remains are uncommon.
CHILDREN: ♦♦ – Unstable blocks, clay and quarry waste make the shore unsuitable for a casual family scramble.
ACCESS: ♦ – Current continuity of the historical shore approach needs verification; do not use unmarked descents.
TYPE: – Slipped clay, original beds and mixed quarry debris, with uncertain loose-block provenance.
DIRECTIONS
♦ Reach Portland through Fortuneswell and use an official named car park suitable for your intended open public path. Dorset Council lists Hambro Road, DT5 1LZ, and Grangecroft Road Westcliff, DT5 2AQ; these are different approaches with different possible shore connections.
♦ The original Chiswell promenade-and-steps approach is historical. Its present continuity to the geological ground must be checked before use. Do not assume a cliff-top path reaches the shore or follow an unmarked scramble.
♦ Original geological locality reference: 50.55860°N, 2.44845°W. This is not a verified parking or descent point.
FOSSIL HUNTING
The original field account records brachiopods, bivalves, gastropods and ammonite fragments in clay and rock among the quarry-debris blocks. Complete ammonites are less common than fragments. Dark colour alone does not distinguish Kimmeridge Clay material from the overlying Portland Sand beds.
The local succession includes an independently documented Epivirgatites nikitini horizon. Other names on old collections, including Virgatopavlovia fittoni, need the specimen and bed information checked rather than being automatically replaced or applied to new finds. Reptile bones are significant but uncommon; historical reports do not justify expecting frequent pliosaur or plesiosaur finds.
Observation and photography are appropriate while current collecting terms and the shore route remain unresolved. Do not split every dark block or nodule, dig the slipped clay or climb quarry waste. For separately authorised loose finds, record uncertain provenance honestly and keep associated fragments together.
Image 1: ichthyosaur vertebrae
A chronological record of geological research and discoveries associated with West Weare (Portland).
1978 – Ammonites link distant successions
Cope figured Epivirgatites nikitini material collected one metre above the Exogyra Bed at West Weare. These specimens helped compare British and Russian Upper Jurassic successions; they are exact-locality records rather than a general island fauna.
1987 – Statutory geological interest documented
The Natural England citation records the 1987 notification and specifically recognizes the island’s important West Cliff reptile locality and Portlandian stratigraphy. This is conservation history, not automatic permission to collect.
1996 – Sedimentary breaks correlated
Coe’s sequence-stratigraphical work distinguished regional surfaces in the Portland succession. The modern BGS account applies P1 and P2 to the West Weare/Clay Ope representative section.
2011 – The modern mapped framework published
The BGS district memoir set out the Portland Sand’s six informal divisions and formal Portland Chert and Freestone members, providing a clear replacement for the old guide’s compressed and partly omitted succession.
GEOLOGY
The West Weare succession extends beyond the slipped Kimmeridge Clay emphasised in the old guide. Clay Ope is the type section for the Portland Sand Formation and for a Portland Stone succession with both Portland Chert and Portland Freestone members. Quarrying has truncated particular faces, not removed every higher unit throughout the locality.
The transition records increasingly shallow marine conditions, from mudstone through silty and sandy Portland beds to shell-rich, cherty and ooidal limestone. Lower Black Nore Beds belong to Kimmeridge Clay; Upper Black Nore Beds above the basal Portland marker belong to Portland Sand. Loose dark blocks cannot be assigned from colour alone.
Landslips and tipped quarry waste obscure and mix the original sequence. The historic “weares” were used for grazing before extensive waste tipping, as described in the original account. The detailed geological framework is a record of exposures, not a route requiring scrambling across unstable ground.
The detailed geological succession and important exposure limits at West Weare (Portland).
The useful local succession is much more than slipped Kimmeridge Clay: it includes the Portland Sand type section and the overlying limestone members. Distinguish original in-situ strata from slipped material and imported quarry waste.
ANCHOLME GROUP
The upper Kimmeridge Clay below the Portland succession belongs to this group. Slumped clay and quarry waste obscure parts of the original section.
Kimmeridge Clay Formation
The mudstone at the foot of the succession includes the Lower Black Nore Beds. The Upper Black Nore Beds above the basal Portland marker belong to a different formation; loose dark blocks should not all be labelled Kimmeridge Clay.
Age: Late Jurassic, Tithonian at the uppermost local levels
Lower Black Nore Beds
These beds remain in the Kimmeridge Clay below the Black Nore Sandstone. An independent exact local thickness has not been established.
PORTLAND GROUP
The regressive marine succession records a transition from fine sediment to carbonate-dominated shallow seas. Historic Portlandian usage corresponds broadly to late Tithonian, not a separate modern international stage.
Age: Late Jurassic, Tithonian
Portland Sand Formation
Clay Ope at West Weare is the BGS type section, approximately 30 m thick. The six named divisions below are informal beds, not formal members.
Black Nore Sandstone
The basal marker is a hard sandy dolomitic limestone, up to 0.7 m in the representative Portland section. It separates the Lower and Upper Black Nore successions.
Upper Black Nore Beds
About 8.5 m of siltstone and fine sandstone contains variable carbonate cement. The old field account distinguishes darker blocks from surrounding waste; individual ammonite identifications still require secure provenance.
Exogyra Bed
The lower part of the shell-rich interval contains abundant disarticulated Nanogyra nana oysters and other marine remains. “Exogyra” is the historical bed name, not a reason to use obsolete oyster taxonomy.
Cast Beds
These overlie the Exogyra Bed within the combined shell-rich interval. Cope’s 1978 ammonites came from 1 m above the Exogyra Bed at West Weare; this measured position places the finds above the Exogyra Bed rather than in the Upper Black Nore Beds.
P1 disconformity
A sedimentary break above the Cast Beds precedes the West Weare Sandstones. This surface has regional sequence-stratigraphical significance; it is not a separate formation.
West Weare Sandstones
Despite the traditional name, the representative section comprises approximately 11 m of finely crystalline dolomite. Use the source lithology rather than describing all of it as ordinary quartz sandstone.
Portland Clay
About 6 m of argillaceous dolomite forms the upper Portland Sand division, beneath the P2 break at the base of the limestone formation. It should not be omitted from the succession.
P2 unconformity
The Portland Stone begins above a non-sequence that omits part of the Okusensis zonal succession on Portland. This differs from the older P1 surface.
Portland Stone Formation
BGS defines an approximately 25 m Clay Ope type section through the two members. Original statements that all higher limestone and Purbeck rocks were quarried away must be limited to particular truncated faces, not the whole locality.
Portland Chert Member
Chert-bearing, bioturbated marine limestone forms the lower member, 15–17 m in the BGS Clay Ope type section. Its lower shell-rich marker carries a very different assemblage from the mudstones beneath.
Basal Shell Bed
The shelly basal limestone marks the beginning of the local Portland Stone succession. Regional species lists do not establish which fossils occur at West Weare.
Portland Freestone Member
The BGS Clay Ope type section records roughly 9 m of upper oolitic limestone. It is retained in the full geological framework even where quarrying has removed it from particular northern faces.
Higher Purbeck and quarry truncation
The BGS formation boundary identifies overlying Mupe Member limestone. A new exact bed-by-bed Purbeck section at the old guide’s collecting area is not established here, and the Freshwater caps and northern quarry logs describe different sections.
References
Bgs Dorset Memoir
Bgs Kimmeridge Lexicon
Bgs Portland Chert
Bgs Portland Freestone
Bgs Portland Sand Lexicon
Bgs Portland Stone
Cope 1978
Portland Hambro Parking
Portland Ne Citation
Portland Ne Consent
Portland Westcliff Parking
SAFETY
Unstable boulders, slippery clay, quarry waste and rockfall make the weares difficult terrain. Stay away from cliff bases, faces and edges, never climb unstable waste to reach a bed, and abandon the shore route if waves or tides obstruct return. The remote geological type section is not a family scramble.
EQUIPMENT
For an authorised safe approach, carry a camera, notebook, tide information and wear secure footwear. Do not plan a visit around hammers, chisels or nodule splitting while current collecting terms remain unresolved.
CLEANING AND TREATING
For separately authorised loose finds, support fragile shale or bone, keep associated pieces together and label the bed only when demonstrable. Avoid indiscriminate splitting of dark blocks and nodules. Rare or potentially important material is best left 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
BGS Portland Sand Formation
BGS South Dorset memoir, Portland Group
Cope 1978: exact West Weare ammonites
BGS Portland Stone Formation
BGS Portland Chert Member
BGS Portland Freestone Member
Natural England Isle of Portland citation
Council Hambro Road parking
Council Westcliff parking
ACCESS RIGHTS
The old assertion of no collecting restrictions is not current authorisation. Seek the relevant owner’s terms and follow conservation notices before removal. Do not damage fixed beds, cliffs or important geological features. The Portland SSSI operations document identifies potentially damaging extraction and clearance activities; it does not establish a simple island-wide rule for all loose fossils.
Protected-site information: SSSI Information – Portland.
It is important to follow our ‘Code of Conduct’ when collecting fossils or visiting any site. Please also read our ‘Terms and Conditions’.
LINKS
♦ Fossil Discussions
♦ Fossil Articles
♦ Buy Fossils, Tools and Equipment
♦ Buy Crystals, Meteorites, and Artefacts
♦ Join Fossil Hunts
♦ UK Fossils Network
