Overview
Directions
- From Charmouth, drive on the A3052 (Charmouth Road) to Lyme Regis. Drive through the town, climbing a very steep hill (Pound Road) and then veering to the left, as you exit the town centre.
- Whilst climbing the hill and near the top, you will see a signpost to Monmouth Beach on the left. Take this left hand turn into Cobb Road. Descend towards Monmouth Beach.
- There is a very large car park at the bottom of the hill. This is operated by Lyme Regis Town Council; check the current charges and parking conditions. From here, you can walk to Chippel Bay (Monmouth Beach).
- Car park postcode: DT7 3LE: Google Maps
- What3Words: Collecting area: ///sports.twinkling.uproot
Location photographs
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Fossil Hunting
Bones of ichthyosaurs and other marine reptiles are occasionally recovered from the foreshore, most commonly as small, isolated vertebrae or fragments of limb and rib bone. While not abundant, these remains do appear with some regularity, particularly after periods of strong wave action that scour the beach and remove overlying shingle. Fossils are released by erosion from several limestone and mudstone horizons; not every loose bone or shell comes from one bed beneath the beach. Leave cliffs, ledges and pavements undisturbed. Careful searching around the tide line, especially among rock pools, loose boulders and wave-worn slabs, often proves most productive. Alongside reptile material, it is also possible to encounter fish remains such as scales and bone fragments belonging to early ray-finned fish like Dapedium and Pholidophorus.
The hard limestones of the Blue Lias are particularly fossil-rich and yield abundant ammonites, along with occasional large, well-preserved nautiluses. These fossils are often tightly enclosed within the rock and many of the more impressive specimens require careful preparation, commonly using an air abrader, to fully reveal their detail. Complete shells can be spectacular, preserving ribbing, sutures and body chambers in remarkable clarity. In addition to ammonites and nautiloids, the limestone can contain bivalves, gastropods and crinoid fragments, reflecting a diverse Early Jurassic marine ecosystem.
Some ammonites from the Monmouth pavement exceed half a metre in diameter, with some of the largest and finest examples originating from Chippel Bay. Access to these fossils is limited by the extreme hardness of the limestone, and naturally detached material may be revealed by erosion. Keep away from fresh falls and search only stable material on the open shore. Trace fossils and worn ammonite fragments can also be observed on the beach. The Undercliffs Code requires visible water-worn ammonites to be left undamaged, including loose examples; photograph them rather than collect them. The local fauna includes ammonites such as Coroniceras in the lower Sinemurian beds. The older Psiloceras-bearing succession lies farther west towards Pinhay and should not be treated as the source of every Monmouth ammonite. Within the limestone bands themselves, brachiopods such as Calcirhynchia calcarea are relatively common, alongside the distinctive curved oysters Gryphaea arcuata, whose robust shells often survive transport and abrasion.
The named Fish Bed (Lang Bed 51) is a laminated, calcareous siltstone or silty limestone in the basal Shales-with-Beef Member, above Grey Ledge. It must not be confused with every fish-bearing shale in the wider Lyme succession. Its fine lamination records limited disturbance of the sea floor; fish scales and bone fragments also occur in surrounding dark mudstone. Look for small glossy scales, repeated fin-ray patterns or delicate bone outlines on naturally exposed loose surfaces. A glittering patch is not enough to identify a fish genus, and complete fish are exceptional finds requiring specialist assessment. Keep any matching pieces and the matrix together. Chert blocks on the beach have a separate Cretaceous origin and are not part of this Jurassic Fish Bed.
Fossil photographs
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Discoveries and milestones
Some of the most significant fossil discoveries and scientific milestones from Monmouth Beach, Lyme Regis include its long-standing importance in the history of Lyme Regis fossil collecting, the world-famous Ammonite Pavement, notable marine reptile finds from the foreshore, and the rescue of storm-damaged sections of the pavement for preservation and study.
Early 19th century – Monmouth Beach became part of the classic Lyme Regis fossil coast worked by Mary Anning and other early collectors
Monmouth Beach formed part of the fossil-rich Lyme Regis shoreline that made the town world famous in the early nineteenth century. The Blue Lias ledges and foreshore west of the Cobb became closely associated with the wider Lyme fossil story, especially for ammonites, belemnites and occasional marine reptile remains.
For over 200 years – Lyme Regis became the most famous British Early Jurassic fish locality
The wider Lyme Regis coast, including the Blue Lias around Monmouth Beach, has produced abundant and often beautifully preserved Early Jurassic fossils for more than two centuries. The JNCC site account notes that Lyme Regis is the most famous British Early Jurassic fish site and the type locality for 50 or more species of fish, underlining the scientific importance of this shoreline.
Undated museum record – Chris Andrew’s Monmouth Beach ichthyosaur tooth
Lyme Regis Museum records that its Education Officer, Chris Andrew, found an ichthyosaur tooth on Monmouth Beach. While much smaller than a full skeleton, it is a good example of the kind of vertebrate material that still turns up among the Blue Lias ledges and foreshore debris.
2017 – storm damage broke parts of the Ammonite Pavement and led to a rescue operation
After the winter storms of 2016–2017 damaged parts of the famous Monmouth Beach ammonite pavement, scientifically important slabs were removed and preserved. The Natural History Museum described the rescued material as a piece of 199-million-year-old fossil seabed and used it to highlight the extraordinary abundance and size of the Monmouth Beach ammonites.
Modern understanding – Monmouth Beach remains one of the best known ammonite ledges on the Jurassic Coast
Today Monmouth Beach is still best known for the Ammonite Pavement, a Blue Lias limestone ledge packed with large ammonites, especially Coroniceras, together with other fossils such as Gryphaea, crinoids, belemnites, plant remains and occasional marine reptile material. It remains one of the easiest places on the coast to see fossils in situ on the foreshore at low tide.
Geology
Monmouth Beach and Chippel Bay, west of the Cobb, expose Blue Lias limestone and mudstone beds beneath the Charmouth Mudstone Formation. The repeated hard ledges and softer shales record Early Jurassic marine deposition. Folding changes which beds reach the beach, and some named ledges reappear along the shore. This guide is focused on the western shoreline rather than the separate Church Cliffs–Black Ven coast east of Lyme Regis.
Overlying the Blue Lias are younger units that further shape the unstable nature of the cliffs. The Shales-with-Beef Member, part of the Charmouth Mudstone Formation, rests directly above the Blue Lias and is composed mainly of dark, fissile mudstones. These beds are often heavily fractured and include bands of fibrous calcite known as “beef,” formed by mineral growth within the compacting sediments. Above this lies the Black Ven Marl Member, a softer and more clay-rich sequence that readily weathers and contributes to frequent landslides. Material from both of these units commonly appears on the beach as loose blocks, slabs, and debris, transported downslope by repeated cliff collapses. Because of this continual movement, the cliffs in this area are extremely hazardous, and fossil collecting must be restricted to the foreshore well away from the cliff base, where sudden rock falls are common and unpredictable.
The repeated limestone ledges and softer mudstones help explain the different preservation styles on this western shore. Early-cemented limestone can retain three-dimensional shells and burrows, while delicate fossils in laminated mudstone are more often flattened. The Ammonite Pavement preserves large coiled shells alongside the traces of animals living in the sea floor. Record the rock type and find position rather than treating every loose fossil as coming from the same ledge. The intact pavement is a feature to observe and photograph, not to extract.
At Chippel Bay, the Blue Lias is particularly well exposed. The traditional named ledges around the upper Hettangian and lower Sinemurian succession provide a detailed field framework. Older H-beds occur farther west towards Seven Rock Point and Pinhay Bay; they are not all assumed to be exposed on Monmouth Beach. Above Grey Ledge, the Fish Bed and Table Ledge belong to the Shales-with-Beef Member in current usage. The Glass Bottle limestone lies below Grey Ledge, within the Blue Lias. This distinction prevents older quarrying terminology from confusing the modern formation boundary.
Shales with Beef and the Black Ven Marls can also be seen above the Blue Lias. The Gault Clay is mostly covered up.
Scattered across the beach are numerous blocks of Lower Cretaceous Upper Greensand of Albian age, easily recognised by their distinctive texture and colour. These rocks were originally deposited in shallow marine conditions and are commonly associated here with large, resistant blocks of chert. The chert often preserves trace fossils, including well-defined worm tubes, along with a variety of heavily worn and reworked fossil fragments that hint at the rich marine life present at the time of deposition. Their durability allows them to survive prolonged transport and abrasion, which explains their abundance on the foreshore compared with the softer surrounding sediments.
The wider undercliff west of Lyme Regis also contains much younger Cretaceous rocks above the Jurassic succession. Lower Cretaceous Upper Greensand is present in that regional cover, with Chalk higher in the succession; it is therefore incorrect to describe the Lower Cretaceous as absent. Displaced Cretaceous blocks on the Monmouth shore are kept separate from the in-situ Blue Lias and Charmouth Mudstone framework.
The explanation lies in the dramatic geomorphological history of the area. The coastline has been profoundly reshaped by a series of large-scale landslides that have transported material from much higher levels downslope and seaward. Many of the Cretaceous blocks found on the beach originated from cliffs that once stood considerably inland, before slope failure caused vast sections of the landscape to slump forward. Around 500 metres inland from the present Lias cliffs, the original, unslipped cliff line can still be identified, with the upper Cretaceous rocks preserved in their original position. These relict cliffs provide clear evidence of the scale of past movement and help to explain the otherwise puzzling presence of younger Cretaceous rocks resting among much older Jurassic strata on the shore.
Detailed geology and bed-by-bed succession
This is a detailed stratigraphic breakdown of the Lower Jurassic succession at Monmouth Beach and Chippel Bay, Lyme Regis, Dorset. The locality exposes a world-famous section through the Blue Lias Formation, with classic named limestone ledges and shale intervals ranging from the Hettangian up into the lower Sinemurian, and the lower part of the overlying Shales-with-Beef Member visible in the cliffs above.
The CB labels are editorial section identifiers, not published bed numbers. Lang’s numbers are given separately where supported. Structural and older westward context is distinguished from actual Monmouth–Chippel beds; no new formal members are created for the informal ledge groupings.
LIAS GROUP
Blue Lias Formation (Lower Jurassic — Hettangian To Lower Sinemurian)
Structural Setting Of Monmouth Beach And Chippel Bay
Context CB1 — Chippel Bay Anticline And Foreshore Ledge System
The Blue Lias at Monmouth Beach and Chippel Bay is exposed in a structurally controlled foreshore and cliff section in which the beds rise westward and successively older beds appear toward Seven Rock Point and Pinhay Bay. The Chippel Bay anticline brings upper Hettangian beds close to beach level, while small normal faults locally offset the upper Hettangian and basal Sinemurian ledges. The sequence is famous for its laterally persistent limestone pavements, many of which were named by Lyme quarrymen and used in the classic work of W.D. Lang. These beds were formerly worked for cement and building stone, which is why the local stone-band nomenclature is unusually rich and detailed.
Lower Named Blue Lias Beds
Bed CB2 — Brick Ledge (Lang Bed 1)
Brick Ledge is one of the lowest named Blue Lias markers used in the Lyme Regis coastal logs and is particularly well exposed toward Seven Rock Point and the western side of Chippel Bay. It consists of several thin, closely spaced argillaceous limestone beds broken by numerous joints so that the rock has a distinctive brick-like appearance. It marks the base of the beds historically worked for cement at Lyme Regis and lies within the higher Hettangian part of the Blue Lias, in the Schlotheimia angulata interval. It is a very useful field marker because it is conspicuous, persistent and clearly different from the less obviously named lower Hettangian cementstone cycles below and westward into Pinhay Bay.
Ammonites
Schlotheimia spp. in the broader angulata interval, with early Hettangian faunas continuing downward westward toward Seven Rock Point and Pinhay Bay.
Context CB3 — Older H-Beds Westwards Towards Pinhay Bay
Westward beyond the Chippel Bay anticline, the section passes down into the lower unnamed Hettangian H-beds of Lang’s framework. These are thinner, more argillaceous limestone–mudstone cycles than the upper named ledges higher in the cliff and foreshore. They include the lower half of the Hettangian and continue down toward the base of the Jurassic in the Psiloceras planorbis Zone. At Monmouth Beach itself these beds are not the main collectible ledge sequence, but they are geologically crucial because they demonstrate that the full lower Blue Lias succession is present west of Lyme Regis.
Ammonites
Psiloceras in the lower Hettangian westward, then upward into Schlotheimia faunas in the higher Hettangian.
Upper Hettangian Ledge Sequence
Bed CB4 — Lower Skulls To Upper White Interval
This part of the upper Hettangian Blue Lias comprises a stack of argillaceous limestone ledges and intervening shales, including the traditional quarrymen’s names Lower Skulls, Upper Skull Shales, Upper White Shales and Upper White. These beds represent repeated limestone–mudstone cycles deposited on a shallow marine shelf under fluctuating oxygenation and sediment input. Many of the limestone bands preserve uncrushed ammonites because they lithified early, while the shales tend to flatten and compact fossils. The ledges are often burrowed, shell-bearing and locally rich in oysters such as Gryphaea arcuata.
Fossil Content
Gryphaea arcuata, small bivalves, ammonites of the higher Hettangian, and shell-rich ledge surfaces showing benthic colonisation.
Lower Skulls (Lang Bed 7)
A nodular limestone marker; the quarry name refers to its irregular concretionary appearance.
Upper Skull Shales (Lang Bed 14)
The separately named shale interval higher in the traditional Blue Lias log.
Upper White Shales (Lang Bed 16)
Shales immediately below the Upper White limestone.
Upper White (Lang Bed 17)
A conspicuously bioturbated limestone. West’s compilation of Lang records includes Gryphaea at this horizon.
Bed CB5 — Specketty Shales And Specketty
A shale-and-limestone pair close to the top of the Hettangian succession at Chippel Bay. Specketty is one of the most useful upper Hettangian ledges in the field because it lies immediately below the boundary interval with the Second Mongrel beds. The bed is associated with abundant shell material and contributes to the distinctive stepped ledge topography of the Monmouth Beach foreshore.
Interpretation
Specketty lies very close to the top of the Hettangian, just below the base of the Second Mongrel interval, which is used locally to approximate the Hettangian–Sinemurian boundary.
Bed CB6 — Second Mongrel Shales And Second Mongrel
A shale and limestone pair forming one of the key boundary intervals at Chippel Bay. The base of the Second Mongrel is commonly taken as the most practical local approximation to the Hettangian–Sinemurian boundary in the field. The limestone is more resistant than the underlying shales and forms an obvious ledge that can be followed along the foreshore under favourable tidal conditions.
Boundary Significance
The base of the Second Mongrel is the best practical field guide to the Hettangian–Sinemurian transition in the Chippel Bay cliff and foreshore section.
Basal Sinemurian Bucklandi Sequence
Bed CB7 — Mongrel Shales And Mongrel (Lang Beds 22–23)
The Mongrel is one of the best-known named Blue Lias ledges at Lyme Regis and Chippel Bay. It is a conspicuous limestone ledge associated with the basal Sinemurian and lies only a short distance above the boundary interval. The bed is notable because it is effectively a rhynchonellid-rich horizon, indicating a short-lived phase of well-oxygenated benthic conditions close above bituminous mudstones. The contrast between shelly benthic limestone and nearby darker shales shows how rapidly environmental conditions fluctuated during Blue Lias deposition.
Fossil Content
Rhynchonellid brachiopods, oysters, ammonites and shell-rich ledge surfaces.
Bed CB8 — Top Copper Shales And Top Copper (Lang Beds 24–25)
One of the easiest named beds to identify in the Blue Lias west of Lyme Regis. The Top Copper is a pyrite-rich limestone with a coppery weathering appearance caused by abundant iron sulphide, though there is no true copper mineralisation. Pyrite occurs as nodules and veins aligned along joints, showing that sulphide mineralisation post-dated early lithification. The Top Copper belongs to the basal Sinemurian part of the succession and is a very useful field datum in the Bucklandi sequence.
Bed CB9 — Second Tape Shales And Second Tape (Lang Beds 26–27)
A shale–limestone pair above the Top Copper. These beds are part of the lower Sinemurian arietitid sequence and continue the characteristic Blue Lias alternation of early-lithified limestone ledges and recessive bituminous or marly shales. Gryphaea arcuata is known from both the shales and the limestone in this part of the sequence.
Bed CB10 — Top Tape Shales And Top Tape (Lang Beds 28–29)
The Top Tape is the easiest ammonite bed to find at Chippel Bay. It forms a very conspicuous ledge in the middle of the bay and carries an almost pavement-like concentration of large arietitid ammonites. Early cementation has prevented compaction of many shells, so large ammonites are often preserved in relief within the stone band. This is one of the classic Monmouth Beach fossil horizons and one of the reasons the site is so well known to collectors.
Ammonites
Large arietitid ammonites dominate the pavement. The cited field guide describes forms as Coroniceras but explicitly cautions that its generic identifications were assembled at different dates and are not a taxonomic revision.
Bed CB11 — Third Quick Shales And Third Quick (Lang Beds 30–31)
A well-marked limestone and shale couplet above the Top Tape. The Third Quick is one of the thick “Quick” limestones that give the upper Blue Lias much of its stepped, ledged foreshore appearance. The Third Quick Shales (Lang Bed 30) beneath it include bituminous shale and marl alternations that are important in Blue Lias cyclostratigraphy. Crinoid ossicles, especially Pentacrinites or Isocrinus, have been recorded from the Third Quick Shales in the Chippel Bay sequence.
Bed CB12 — Gumption Shales And Gumption (Lang Beds 32–33)
The Gumption Shales are unusually thick, about 1.27 m in the classic Chippel Bay sequence, and make this part of the cliff and foreshore particularly easy to identify. The Gumption limestone above continues the thick-ledge style of the upper Blue Lias, and together these beds are among the most useful field markers in the Bucklandi sequence. Bituminous shale and marl cycles are especially obvious here, making the interval important for discussions of Blue Lias cyclicity.
Bed CB13 — Second Quick Shales And Second Quick (Lang Beds 34–35)
Another thick limestone–shale couplet within the lower Sinemurian Blue Lias. The Second Quick forms a strong ledge and, together with the underlying Gumption interval, helps define the upper part of the Bucklandi succession at Monmouth Beach. These beds continue the pattern of argillaceous limestone with abundant marine fossils and softer, more bituminous interbeds.
Fossil Content Through The Bucklandi Sequence
Large arietitid ammonites, especially Coroniceras and allied forms, Gryphaea arcuata, crinoid ossicles, nautiloids and associated marine bivalves. Some ledges preserve unusually complete ammonites because of early cementation.
Higher Sinemurian Blue Lias
Bed CB14 — Best Bed And Overlying Upper Blue Lias Ledges
Higher in the Blue Lias succession the named ledges become less widely used by collectors than the spectacular Bucklandi beds below, but they remain stratigraphically important. Best Bed (Bed 41) is one of the laterally persistent limestone markers recognised west of Lyme Regis, and together with the higher ledges it shows that the upper Blue Lias remained strongly cyclic. These beds are still fossiliferous and continue to yield ammonites, oysters and other marine fossils from the higher Sinemurian part of the sequence.
Bed CB15 — Venty, Top Quick And Glass Bottle Limestones
These upper Blue Lias limestones form prominent ledges in the intertidal zone at Lyme Regis and westward toward Chippel Bay. They belong high in the Blue Lias succession, just below the top of the formation, and are useful markers for the uppermost limestone-shale cycles before the transition into the Charmouth Mudstone facies above. Their ledges are less famous commercially than Top Tape, but they are important stratigraphically because they lead up to Grey Ledge.
Venty (Lang Bed 43)
A named upper Blue Lias limestone above the Best Bed interval.
Top Quick (Lang Bed 45)
The higher named Quick limestone, above Venty in the published bed sequence.
Glass Bottle (Lang Bed 47)
A Blue Lias limestone below Grey Ledge (49), rather than a Shales-with-Beef marker.
Bed CB16 — Grey Ledge (Lang Bed 49)
Grey Ledge is the natural top of the Blue Lias at Lyme Regis and forms one of the key regional marker beds. It is a persistent argillaceous limestone with numerous ammonites and characteristic dark-grey-filled Arenicolites and Diplocraterion burrows. A bioturbated erosion surface caps the bed, and this surface is now taken as the top of the Blue Lias in modern stratigraphical usage. Loose blocks from Chippel Bay and adjacent shore sections have yielded large ammonites such as Paracoroniceras lyra from high in the Blue Lias, around the base of the Semicostatum Biozone.
Ammonites
Higher Sinemurian arietitids including Paracoroniceras lyra, with Arnioceras also present in high Blue Lias blocks from the Chippel Bay area.
Total Thickness Of Blue Lias Formation At Lyme Regis And Chippel Bay: Approximately 26–32 Metres
Charmouth Mudstone Formation (Lower Jurassic — Above The Blue Lias)
Shales-with-Beef Member (Selected Basal Beds Described Below)
Bed CB17 — Bioturbated Surface Above Grey Ledge
The top of Grey Ledge is capped by a bioturbated erosion surface that forms the key boundary between the Blue Lias and the overlying mudstone-dominated Charmouth Mudstone Formation. This surface is easy to recognise where exposure is good and marks a significant facies change from ledge-forming limestone–mudstone couplets to darker, more fissile mudstones.
Bed CB18 — Fish Bed (Lang Bed 51)
The Fish Bed is one of the most persistent lower Shales-with-Beef marker beds west of Lyme Regis and can be correlated regionally in the highest intertidal and low-cliff exposures beyond Chippel Bay. It is a thin calcareous siltstone/limestone horizon within darker mudstones and is important for correlation because the basal Shales-with-Beef beds vary laterally more than the underlying Blue Lias.
Bed CB19 — Table Ledge (Lang Bed 53)
A laterally persistent muddy limestone in the lower Shales-with-Beef Member and one of four useful correlation horizons west of Lyme Regis: Best Bed and Grey Ledge in the Blue Lias, and Fish Bed and Table Ledge in the Shales-with-Beef. Table Ledge lies above the Fish Bed and marks the early part of the transition into the darker, beef-bearing mudstone succession that dominates the cliffs higher west of Lyme Regis and toward Black Ven.
Devonshire Head Limestone (Lang Bed 71) — Higher Shales-with-Beef Context
The Devonshire Head Limestone is a persistent marker within the Shales-with-Beef framework. Gallois’s 2011 Ware Cliffs landslip study uses this horizon to locate levels within the Shales-with-Beef affected by movement, distinct from the Blue Lias limestones below. It is not an extra formation or the top of the Blue Lias.
Birchi Nodules — Upper Shales-with-Beef
The western field account describes compound carbonate nodules just beneath the Birchi Tabular limestone. Their calcite, ferroan-dolomite and fibrous-calcite components record successive cement growth. The nodules and tabular bed should not be merged into a single layer. The higher cliff continuation reaches the lower Black Ven Marl Member, but a full Black Ven measured section is not reconstructed here.
Black Ven Marl Member
Birchi Tabular Bed — Base Of The Black Ven Marl Member
The tabular limestone above the Birchi Nodules marks the base of the Black Ven Marl Member in the current BGS definition. It is a separate boundary bed, not part of the underlying nodular horizon or an additional Shales-with-Beef layer. Its occurrence in the higher Ware Cliffs succession is documented by Gallois (2011); the complete Black Ven type log is not transferred to Monmouth Beach.
Depositional Environment
Monmouth Beach and Chippel Bay record shallow-marine shelf deposition during the earliest Jurassic. The Blue Lias consists of repeated cycles of argillaceous limestone, marl and bituminous shale, reflecting fluctuations in carbonate productivity, clastic input, oxygenation and early cementation. The limestone ledges lithified early and commonly preserve uncrushed ammonites, whereas fossils in the shales are usually flattened. Upward through the section, the succession passes from higher Hettangian ledges into the spectacular basal Sinemurian arietitid beds and then up to the burrowed Grey Ledge at the top of the formation, above which darker mudstones of the Shales-with-Beef Member mark a change to more mud-rich marine sedimentation.
Thickness Note: The Named Beds Summarised Here Do Not Form A Single Continuously Measured Monmouth Beach Section; No Combined Local Thickness Is Assigned
References
Lang, W.D. (1924). The Blue Lias of the Devon and Dorset coasts.
Gallois, R.W. & Paul, C.R.C. (2009). The highest part of the Blue Lias and lowest Shales-with-Beef on the Devon–Dorset coast.
British Lower Jurassic Stratigraphy (GCR volume) for the Lyme Regis coast and Blue Lias framework.
Ian West, Lyme Regis westward field guide and associated Blue Lias bed notes.
British Geological Survey framework sources for the Blue Lias and Charmouth Mudstone formations.
Ian West: Lyme Regis westward field guide (named beds and local exposure).
Gallois and Paul (2009): upper Blue Lias and basal Charmouth Mudstone.
Gallois (2008): Shales-with-Beef lithostratigraphy.
Gallois (2011): fossil landslide and Ware Cliffs stratigraphy.
BGS: Sidmouth district geology.
Safety
Common sense when collecting at all locations should be used and prior knowledge of tide times is essential. Care should especially be taken at the headland, where the sea reaches the base of the cliffs at high tide. If you venture past this point, return in good time. Care must also be taken of falling rocks. These are frequent because the alternating hard limestone and shale of the Blue Lias make the cliffs highly unstable and prone to collapse.
Equipment
Search visually first. A small trowel can help lift finds from loose shingle or detached soft sediment, and modest hand tools with safety glasses may be useful for appropriate small loose pieces. Follow the Undercliffs Code: avoid breaking up larger blocks and boulders, leave rock ledges and ammonite pavements intact, and do not dig into cliffs. Keep promising nodules and unusual bones intact for specialist advice.
Cleaning And Treating
Begin with gentle dry brushing of loose sediment, stopping if the fossil or matrix crumbles. Do not apply a fixed soaking treatment to every specimen: pyritic fossils, fragile Chalk specimens and friable mudstone need assessment before any wet cleaning. Water cleaning is appropriate only where the material is sound and water-safe. Let wet finds dry gradually at room temperature, away from radiators and other heat sources.
Sound specimens do not need routine coating. Where a fragile fossil needs consolidation, seek advice on selective consolidation with Paraloid B-72. It is soluble in suitable solvents, but complete removal from porous fossils or matrix cannot be guaranteed. A consolidant is not a cure for active pyrite decay, and treatment should preserve diagnostic surfaces and any useful adhering matrix.
Avoid decorative varnish on ammonites: a glossy coating can obscure surface detail and complicate later preparation. Leave potentially important specimens uncoated and seek specialist advice before cleaning or treating them.
Identify Your Finds
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Further Reading
Deposits Magazine – Giant file clams: A common fossil as an exciting document of Earth history
Monmouth Beach — Dinosaurland Fossil Museum
Ammonite Pavement — Love Lyme Regis
Lyme Regis Discovery Trail: Monmouth Beach
Access Rights
Monmouth Beach forms part of the Axmouth to Lyme Regis Undercliffs SSSI and National Nature Reserve. Follow the Undercliffs Fossil Collecting Code and local signs. Loose beach material may be collected responsibly; in-situ excavation normally requires prior Natural England permission. Leave visible water-worn ammonites in place, including loose examples; do not collect or damage them. Leave the fossil pavements and rock ledges intact and seek advice about important or at-risk specimens before attempting recovery.
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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