Quantoxhead is a quiet and expansive stretch of the Somerset coast, where tall Jurassic cliffs and a wide wave-cut platform provide excellent fossil exposure. The foreshore regularly yields ammonites and occasional reptile remains, often after erosion, while the long rocky platform also features numerous rock pools, making it both a productive and scenic location to explore.
FIND FREQUENCY: ♦♦♦♦♦ – Quantoxhead is highly productive for fossils, especially for reptile remains and large ammonites. Shells and fish remains can also be found.
CHILDREN: ♦♦♦♦ – This location is suitable for families, as there is lots for the kids to do, including plenty of huge rock pools to explore, which are full of sea life. However, it can be a long walk for some. Keep children well away from the base of the cliff.
ACCESS: ♦♦♦ – Access to Quantoxhead beach is fairly easy, but the location itself can be difficult to find. You should head to East Quantoxhead. We would recommend watching the video which shows the walk down to the steps from the car park.
TYPE: This is a cliffs and foreshore location. Fossils are found mostly exposed on the foreshore within the rocks, or amongst the areas of shingle.
DIRECTIONS
♦ Quantoxhead can be quite difficult to find. It is best to follow the A39 to East Quantoxhead and turn up Frog Street.
♦ Follow this road until you get to the church. There is a large pond with ducks here and, on the opposite side of the road, is a church car park. The church is quite happy for you to park here, but you should make a small donation in the donation box.
♦ Follow the footpath round the back of the pond all the way. You will reach a point where there is a track ahead, and a path that continues round the left. Take the path to the left and keep following. You will eventually come to a warning sign about dangerous cliffs, and access to the beach via some steps on the left side. This can be a bit of a long walk for some.
♦ Car park postcode: TA5 1EJ: Google Maps
♦ What3Words: Steps to beach: ///dormant.insect.trickling
VIDEO FILM
FOSSIL HUNTING
Quantoxhead is a productive Blue Lias fossil locality, yielding a diverse range of marine vertebrate and invertebrate fossils typical of the Early Jurassic seas. The site is particularly well known for marine reptiles and ammonites, but many other fossil groups can also be found.
Marine reptile remains are among the most significant fossils from Quantoxhead. Fragmentary bones of ichthyosaurs and plesiosaurs are the most commonly encountered vertebrate fossils, typically including vertebrae, ribs, limb elements, and occasional skull fragments. Ichthyosaurs recorded from the wider Blue Lias of Somerset include forms such as Ichthyosaurus and Stenopterygius, while plesiosaur material is generally attributed to early plesiosauroids, often referred to historically as Plesiosaurus.
Although much rarer, other marine reptiles have also been recorded from this locality, making Quantoxhead an important site for vertebrate diversity.
Fish remains are also present and often occur alongside reptile material. These typically include scales, vertebrae, teeth, and fin spines. Fish from the Blue Lias commonly belong to genera such as Dapedium and Lepidotes, though material at Quantoxhead is usually fragmentary rather than complete.
Quantoxhead is well known for its ammonite fauna, with many different species recorded from the Blue Lias sequence. Commonly encountered ammonites include Early Jurassic genera such as Psiloceras, Caloceras, Arietites, and Coroniceras. These range from small, finely ribbed forms to much larger, more robust shells, particularly as you move west along the foreshore.
Ammonites are frequently preserved as impressions in foreshore rocks, and complete or partial shells may be found weathering out of limestone blocks following fresh cliff falls.
In addition to ammonites, a single species of nautiloid has been recorded at Quantoxhead, typically assigned to the genus Cenoceras. These are much less common than ammonites but are a notable part of the site’s cephalopod fauna.
Belemnites are present but relatively uncommon compared to other Blue Lias localities. When found, they are usually fragmentary guards, most often belonging to early Jurassic forms such as Passaloteuthis.
Bivalves are abundant and diverse at Quantoxhead, with over 20 species recorded. Commonly encountered forms include oysters such as Gryphaea, scallop-like species including Pecten and Lima, and burrowing bivalves such as Pholadomya. Many bivalves are preserved as single valves, though articulated specimens can occasionally be found.
Brachiopods are less common than bivalves but still form an important part of the assemblage. Typical Blue Lias genera recorded from the area include Terebratula and Rhynchonella, usually found as isolated shells.
Crinoids are very common at Quantoxhead but are usually found as small, broken fragments rather than complete specimens. These fragments are particularly abundant within the shale layers and often occur in the same horizons as fish and reptile remains.
Other echinoderm material includes the occasional echinoid spine, though these are relatively rare.
Trace fossils are also present and include burrows produced by bivalves and other invertebrates. These traces can often be seen on bedding planes and weathered surfaces along the foreshore.
There are two particularly interesting fossil-producing sections at Quantoxhead, though both require a very long walk to reach.
Reptile remains are most commonly found within the soft foreshore shales, which generally begin around 2 km west of the steps. Bones are often discovered in the same layer as abundant crinoid fragments, with fish remains also present. Where harder horizons occur within this zone, vertebrate material can occasionally be exceptionally well preserved.
Further west, ammonite impressions become increasingly common in the foreshore rocks, with specimens generally increasing in size the farther you walk. Following fresh cliff falls, ammonites may be found loose on the beach, having weathered out of limestone blocks. Ammonites can also be found within limestone blocks throughout the Quantoxhead area.
Some of the most significant fossil discoveries and scientific milestones from Quantoxhead include classic early Jurassic ammonite work, the recognition of the East Quantoxhead section as the world reference point for the base of the Sinemurian Stage, and the long-standing importance of the coast for ammonites and marine reptile remains.
Early Jurassic ammonite faunas – Quantoxhead became important for very early Sinemurian ammonites
The East Quantoxhead coast is one of the most important Lower Jurassic ammonite localities in Britain because it preserves one of the earliest known Sinemurian ammonite assemblages. Fossils from this section, especially arietitid ammonites, became crucial for recognising the base of the Sinemurian Stage.
1995 – East Quantoxhead proposed as a candidate GSSP for the base of the Sinemurian
Kevin Page proposed the East Quantoxhead section as a candidate Global Stratotype Section and Point for the base of the Sinemurian Stage. This was a major scientific milestone, as it meant the cliffs here were being considered as the international standard for a boundary in the geological timescale.
2000 – East Quantoxhead selected as the global reference section for the base of the Sinemurian
The East Quantoxhead section was selected as the GSSP for the base of the Sinemurian Stage. The boundary is defined by the first appearance of the ammonite genera Vermiceras and Metophioceras, making the locality internationally important in Jurassic stratigraphy.
2002 – the East Quantoxhead GSSP was fully formalised in print
The formal published account of the Sinemurian GSSP confirmed East Quantoxhead as the world reference point for this stage boundary. This cemented Quantoxhead’s place as one of the most scientifically important Lower Jurassic coastal sections in Britain.
Modern collecting – Quantoxhead remains important for ammonites and marine reptile remains
As well as its stratigraphic importance, Quantoxhead is also well known as a productive fossil locality. The foreshore and fallen blocks can yield ammonites, bivalves, brachiopods and occasional marine reptile material, including ichthyosaur bones, showing that the site remains important both scientifically and for fossil collecting.
GEOLOGY
The shoreline at East Quantoxhead exposes a classic Lower Jurassic (Lower Lias) coastal section, cut into the Blue Lias Formation. Here, the cliffs and foreshore reveal a thick alternation of soft grey clays and mudstones with repeated hard limestone beds, creating one of the best “textbook” examples of how limestone–mudstone rhythms shape a coastline. The beds generally dip gently northwards and eastwards, so as you walk along the shore you effectively move up and down through the sequence depending on direction and tide level.
The Blue Lias here is built from repeating layers of:
- Mudstone/clay-dominated intervals that weather quickly, slump easily, and form the more eroded parts of the cliff and foreshore.
- Limestone beds that resist wave attack, breaking out as large, blocky slabs and platforms.
This contrast is what makes Quantoxhead so visually dramatic. After storms or fresh erosion, the limestones stand proud as sharp ledges and steps; in calmer periods the mudstones soften and wash away, leaving the limestone beds as isolated ribs, pavements, and boulder trains across the intertidal zone.
The Blue Lias is also familiar from Dorset, but the East Quantoxhead boundary section is considerably more expanded. At Limekiln Steps, Bed 145 contains the internationally agreed base of the Sinemurian Stage, 0.90 m above the bed’s base. The boundary lies within paper shale rather than at the start of a new formation.
Because the strata dip eastwards, the coastline often presents:
- A two-level foreshore: lower, muddier zones that are smoother and more easily scoured, and higher, limestone-dominated zones that form steps and benches.
- Natural “staircases” where successive limestone beds create repeated ledges.
- Wide wave-cut platforms at low tide, with the limestone layers acting like hard shelves.
The dip also influences where the sea undercuts: softer horizons are preferentially eroded, which can destabilise overlying limestone beds and promote block falls and slabby collapses onto the shore.
Faulting and the “stepped circles”
One of Quantoxhead’s standout geological features is the faulted nature of the coastal section. Several major faults run through this stretch of coast, and they can be picked out even without close inspection because they:
- Offset limestone beds, so a single layer may “jump” up or down across a fracture line.
- Create zones of broken, jumbled blocks where the rocks are more fractured.
- Control erosion, producing gullies, small inlets, and changes in foreshore level.
This is a detailed composite stratigraphic breakdown of the Lower Jurassic succession relevant to the Quantoxhead coast, centred on the Limekiln Steps section north of East Quantoxhead and correlated with adjacent west Somerset foreshore sections. The locality is internationally important because Bed 145 contains the Global Stratotype Section and Point for the base of the Sinemurian Stage within one of Britain’s most complete ammonite-bearing Hettangian–Lower Sinemurian successions.
The guide’s access route is from East Quantoxhead to Limekiln Steps. The local reference interval is the approximately 27 m GSSP study section, not the entire numbered west Somerset succession. Earlier and later bed descriptions are retained below as clearly labelled regional correlation context; they do not assert that every bed or fossil occurs at the steps.
LIAS GROUP
Blue Lias Formation (Hettangian To Lower Sinemurian)
The Quantoxhead coast has to be read as part of the wider west Somerset composite Lower Lias section, not as one isolated vertical cliff log. The internationally important Limekiln Steps exposure lies in the upper Hettangian to lowermost Sinemurian part of the succession, while lower and higher numbered beds are correlated along the same coastal tract; the bed numbers used below are the formal published west Somerset numbers of Whittaker & Green. In current BGS lithostratigraphy the Blue Lias extends from the base of the fissile mudstone above the Sun Bed to the top of Bed 238, even though the published numbered succession continues upward into the basal Charmouth Mudstone Formation.
Regional Lower Hettangian Context: Beds 1–94
These lower intervals are best documented elsewhere along the west Somerset reference coast, especially St Audries and Doniford. They provide stratigraphic context below the East Quantoxhead GSSP interval, not an additional measured exposure at Limekiln Steps.
Beds 1–7 — Basal Pre-Ammonite Blue Lias (c. 5 m)
Grey calcareous mudstones and rather nodular dark blue-grey limestones form the basal Lias above the Sun Bed. About 5 m of strata are present before ammonites become established. The fauna is chiefly bivalved, with Liostrea hisingeri especially characteristic at some levels, together with other marine shells. These beds record the earliest fully marine Blue Lias conditions on the west Somerset coast, but they remain pre-Psiloceras in ammonite terms and are therefore important for understanding the transition from the latest Penarth facies into the earliest Jurassic sea.
Beds 8–12 — Earliest Psiloceratid Beds
The first psiloceratid ammonites appear as low as Bed 8. Weakly ribbed Psiloceras, including P. erugatum, together with Neophyllites, occur below the more typical smooth Psiloceras forms of the classic planorbis interval. Lithologically these beds continue the familiar Blue Lias rhythm of dark calcareous mudstone, marl and thin limestone, with marine faunas still comparatively sparse. They are significant because they show that the earliest Jurassic ammonite succession on the wider west Somerset coast begins below the abundance phase of P. planorbis.
Beds 13–19 — Psiloceras planorbis Beds
Unequivocal Psiloceras planorbis is abundant in these beds, making them the classic lower Planorbis Subzone in the west Somerset sequence. The succession is composed of interbedded dark grey mudstones and thin nodular limestones, with fossils commonly flattened in the mudstones but more three-dimensional in the limestones. The Planorbis Subzone extends upward to the base of Bed 25 and is about 4.5 m thick in the standard west Somerset log. These beds are among the key British reference levels for the earliest ammonite-defined Jurassic.
Beds 20–23 — Upper Planorbis Subzone Below The Laminated Mudstones
These beds continue the upper part of the Planorbis Subzone below the famous laminated Bed 24. Bivalves remain common, and the broader Planorbis interval in west Somerset has yielded Liostrea, Camptonectes, Protocardia, Pteromya, echinoids such as Diademopsis and Eodiadema bechei, and occasional vertebrate material. Deposition was still strongly cyclic, but the increasing development of laminated, organic-rich mudstones foreshadows the more restricted conditions of Bed 24.
Bed 24 — Laminated Psiloceras Mudstone (2 m Or More)
Bed 24 is one of the classic west Somerset Blue Lias horizons, comprising 2 m or more of indurated laminated mudstone. Crushed iridescent ammonites of the Psiloceras planorbis group are abundant, and small pyritized colonies of Heterastraea have been recorded from laminated mudstones at this level. Fish remains and ichthyosaur material are known from the Planorbis Zone in the wider GCR coastal section, including an embryo within a large ichthyosaur skeleton from the lower part of the succession. The finely laminated, bituminous lithology indicates deposition under very low-energy, locally dysoxic to intermittently anoxic bottom-water conditions.
Beds 25–42 — Johnstoni Subzone (c. 3.4 m)
Bed 25 is a limestone in which the first appearance of Caloceras marks the base of the Johnstoni Subzone. The subzone is about 3.4 m thick and consists of limestones and mudstones, with hard laminated mudstones in Bed 36 yielding Caloceras johnstoni and Bed 37 yielding C. intermedium. These beds are a classic low Hettangian reference interval in which ammonite biostratigraphy becomes much more precise than in the Planorbis Subzone below.
Beds 43–66 — Lower Liasicus Zone / Portlocki Subzone
The base of the Liasicus Zone is taken at the appearance of Waehneroceras sensu lato in Bed 43. The full Liasicus Zone is about 28 m thick, and its lower part, up to about Bed 69, is notably mudstone-dominated with only subordinate limestone bands. The macrofauna becomes more diverse, including Camptonectes, Gervillia, Lucina, Liostrea, Modiolus, Plagiostoma and Pseudolimea, together with the lowest Gryphaea cf. obliquata. These beds represent a comparatively complete offshore marine record of the early Hettangian shelf in the Bristol Channel–Central Somerset basin system.
Beds 67–79 — Upper Liasicus Zone / Laqueus Subzone
Laqueoceras appears around Bed 67 and marks the boundary between the Portlocki and Laqueus subzones. The lithology remains mainly dark grey calcareous mudstone with persistent Blue Lias limestone couplets, but the succession is less ammonite-poor than the lower Liasicus interval. The regional west Somerset section is valuable here because the expanded mudstone thickness suggests little erosion and a comparatively complete basinward record.
Beds 80–94 — Lower Angulata Zone Below The Complanata Subzone
Bed 80 yields Schlotheimia cf. amblygonia, taken as marking the base of the Angulata Zone. The Angulata succession at west Somerset is about 40 m thick in total and extends upward to Bed 145 through grey mudstones and nodular limestones. Macrofossils are not especially abundant at first, but Gryphaea arcuata becomes increasingly common and the brachiopod Calcirhynchia calcaria becomes an important guide fossil in this part of the section.
Local GSSP Section: Bloos And Page (2002), Figure2
This local log uses the Whittaker–Green numbers on the right of the published figure. Palmer’s C-numbers are a separate scheme on its left. The measured section covers about27 m: upper Complanata, Depressa, Conybeari and lower Rotiforme intervals. The Rotiforme boundary in this figure lies at about bed163, differing from numbered endpoints quoted for the wider GCR composite. The schemes are not silently merged.
Regional Beds95 And99: Context Below The Studied Local Log
The older regional account includes Schlotheimia complanata and related forms at these earlier levels. They precede the local figure’s bed114 starting point and are not part of its measured27 m section.
Bed114 — Basal Plotted Limestone
The lowest numbered horizon in the figure is a limestone bed at the base of the plotted upper-Complanata succession.
Beds115–116 — Incompletely Measured Interval
The authors explicitly state that bituminous shale is not shown separately here because an exact measurement was not possible. The apparently blank graphical interval must not be read as proof that shale is absent.
Beds117–123 — Limestone And Marl Package
Several closely spaced limestone beds and intervening marl occur above the incompletely measured interval. They form part of the local upper-Complanata succession; no individual thickness is inferred from drawing scale.
Beds124–133 — Shale, Marl And Limestone Cycles
The diagram distinguishes repeated dark shale intervals, lighter marl and thin carbonate horizons, including labelled limestone beds 126,130 and132. Schlotheimia occurrences accompany this upper-Hettangian interval.
Bed134 — Depressa Boundary Marker
The lower boundary of the Depressa Subzone is placed at this thin limestone marker in the local figure. The adjacent fauna is shown as Schlotheimia cf. princeps rather than an unqualified species determination.
Beds135–144 — Latest Hettangian Cycles
Dark shale beds alternate with marl and several limestone horizons. Schlotheimia pseudomoreana ranges through much of the interval. These strata lead into bed 145 without a formation change.
Bed145 — Paper Shale And The Stage Boundary
The base of the Sinemurian is 0.90 m above the base of this bituminous shale. The first Vermiceras quantoxense, V. palmeri and Metophioceras mark the boundary within the bed, not at its basal lithological contact.
Bed146 — Earliest Sinemurian Fauna
The earliest arietitid assemblage continues above the boundary. The plot includes overlapping latest Schlotheimia and early arietitid records; this is a local biostratigraphical result, not a claim of a new lithological unit.
Bed147 — Metophioceras sp. indet. B Horizon
The figure associates this low Sinemurian level with an unnamed Metophioceras form, labelled sp. indet. B. The carbonate horizon is part of the continuing limestone–marl–shale rhythm; the provisional label is retained.
Beds148–149 — Low Conybeari Ammonite Interval
Closely spaced, partly irregular carbonate horizons are shown. The fauna plotted at bed 149 includes Metophioceras brevidorsale, Vermiceras conybearoides and V. rougemonti. These records explain why this part of the local succession is more complete than many European counterparts.
Beds150–151 — Intervening Cycles
Shale, marl and limestone separate the earlier bed 149 fauna from the following turnover. A plotted Metophioceras occurrence is unnamed and is not converted into a named species here.
Bed152 — Rotarium Horizon
A dark shale interval is associated with Vermiceras (Epammonites) rotarium in the published plot. The source’s spelling and taxonomic qualification are retained.
Bed153 — Rouvillei Horizon
The next carbonate-bearing interval is associated with Vermiceras (Epammonites) rouvillei.
Bed154 — Provisional Coroniceras Affinity
The plot shows Coroniceras sp. indet. aff. “defneri” near this shale-bearing level. This is an unnamed, qualified identification; it is not the formal younger defneri horizon.
Beds155–159 — Upper Conybeari Cycles
Further limestone, marl and shale cycles contain rapidly changing arietitid faunas. Several labels remain unnamed or affinity-based in the source and are not assigned fabricated modern species names.
Beds160–162 — Latest Conybeari Faunas
The upper Conybeari interval includes the plotted Vermiceras elegans, Metophioceras conybeari and Metophioceras gracile records around beds 161–162. Their sequence is retained without importing the older regional subzone endpoint.
Bed163 — Rotiforme Boundary Interval
The local figure places the change to the Rotiforme Subzone in this interval, with Vermiceras (Epammonites) silvestrei and Coroniceras defneri at the boundary region. It does not place these records at beds 166–167.
Beds164–165 — Lower Rotiforme Continuation
The upper plotted section continues through shale, marl and limestone above the boundary. The detailed study covers only the lower part of the subzone; the higher regional succession is described separately below.
Individual Lithological Horizons Within Figure 2 Packages
These entries preserve each legible numbered horizon in the local diagram, including its original grouped ranges. No thickness is inferred from the image scale, and absent numbers are not manufactured. They supplement the detailed fauna and boundary account above, rather than forming a second succession.
Published Bed 117–119
Grouped carbonate beds are drawn with an irregular contact; the published grouping is retained.
Published Bed 120
A thin marl interval separates the adjacent carbonate packages.
Published Bed 121–123
Several closely spaced limestone beds form a grouped package in the published numbering.
Published Bed 124
A dark bituminous-shale interval is explicitly drawn.
Published Bed 126
A distinct limestone horizon lies above the intervening marl.
Published Bed 127
A marl interval separates the limestone horizons below and above.
Published Bed 128
A thin limestone horizon caps the bed 127 marl interval.
Published Bed 129
The diagram shows a prominent dark shale interval.
Published Bed 130
A thin limestone marker occurs in the upper-Complanata package.
Published Bed 132
A separate thin limestone marker is labelled above bed 130.
Published Bed 135
Dark shale overlies the bed 134 boundary-marker limestone.
Published Bed 136
The source groups a closely spaced limestone package under this number.
Published Bed 137
A comparatively prominent bituminous-shale interval is drawn.
Published Bed 138
A limestone band caps the preceding muddy interval.
Published Bed 139
A bituminous-shale interval forms the darker part of the cycle.
Published Bed 140
A limestone horizon lies between the bed 139 shale and bed 141 marl.
Published Bed 141
The interval is mainly marl, with a thin dark layer at its base.
Published Bed 142–144
The source groups several carbonate horizons and intervening marl; they are not split into invented individual measurements.
Published Bed 150
Dark shale forms the lower part of a cycle above the bed 149 package.
Published Bed 151
A thin limestone horizon lies between the neighbouring muddy intervals.
Published Bed 155
A distinct limestone bed interrupts the muddy succession.
Published Bed 156
A dark bituminous-shale interval is shown below the next limestone.
Published Bed 157
A limestone bed forms the next resistant carbonate horizon.
Published Bed 158
Marly mudrock and a thin darker interval continue the rhythm between limestone markers.
Published Bed 159
A thin limestone marker is drawn beneath the bed 160 shale.
Published Bed 160
Bituminous shale records another dark part of the cycle.
Published Bed 161
A limestone horizon accompanies the late-Conybeari faunal interval.
Published Bed 162
A mudrock interval with dark shale lies above bed 161 and below the subzone-boundary region.
Published Bed 164
Marl in the lower part is overlain by a substantial bituminous-shale interval above the bed 163 boundary region.
Published Bed 165
A limestone horizon lies in the plotted lower-Rotiforme continuation.
Separate Figured-Specimen Records: Figure 8
Bloos and Page (2002), Figure 8, reproduces East Quantoxhead specimen records from their 2000 work. These captioned bed labels are preserved alongside the Figure 2 measured study, including older beds outside its detailed 27 m interval. They do not extend that measured log or impose a new reconciliation between numbering schemes. Names and open identifications follow the cited historical determinations.
Bed 95 — Figured Complanata Specimens
Figure 8 identifies Schlotheimia complanata and S. complanata polita from this bed (Sedgwick Museum specimens X29327 and X29328).
Bed 99 — Figured Oxygonia And Angulosa/Phobetica Specimens
The caption records Schlotheimia oxygonia and the S. angulosa/phobetica group (X29325 and X29326). The group-level identification is retained.
Bed 133 — Figured Striatissima-Group Specimen
Schlotheimia ex gr. striatissima is recorded at the top of the Complanata Subzone (X29324). The affinity qualification is retained.
Bed 134 — Figured Princeps-Affinity Specimen
The upper bed surface yielded Schlotheimia cf. princeps (X29323), interpreted in the caption as probably indicating the depressa horizon.
Bed 145 — Figured Latest Hettangian Specimens
The base of the bed yielded Schlotheimia sp. indet. A and S. pseudomoreana (X29321 and X29322). These are the latest Hettangian records in the caption, below the stage boundary within the bed.
Bed 145 — Fish Concentration And Microfossil Turnover
Bloos and Page (2002, pp. 26–27) describe a thin concentration of fish scales and bones at the stage-boundary level within the bituminous shale; occasional small complete fish are also reported. The concentration helps locate the boundary without implying a break in deposition. The cited microfossil studies record Lingulina tenera plex. substriata in the latest Hettangian, followed by consistent Planularia inaequistriata and the Frondicularia terquemi plexus in the basal Sinemurian. These are the published historical taxonomic usages.
Bed 160 — Figured Elegans Specimens
Figure 9 explicitly assigns the Vermiceras elegans holotype and a second figured specimen to bed 160 (Sedgwick Museum X29335 and X29336). This captioned specimen attribution is retained separately from the placement of the faunal label near bed 161 in Figure 2; the two presentations are not silently forced into one exact horizon.
Higher Regional Continuation Beyond The Detailed GSSP Study
The following intervals give the regional context above the main boundary section. Their complete thicknesses are not assigned to the Limekiln Steps cliff, and regional fossil lists do not establish an exact find horizon there.
Beds 168–202 — Main Rotiforme Subzone (within a c. 32.6 m interval for Beds 165–202)
In the older regional GCR bed correlation, the Rotiforme interval continues through Bed 202, is a thick lower Sinemurian offshore succession dominated by mudstone with recurring laminated, nodular and more persistent limestones. Although the higher biohorizons are less often quoted bed by bed in general summaries, this interval remains important because it preserves substantially more thickness than many equivalent southern British sections and therefore a more complete record of early Sinemurian basin sedimentation.
Beds 203–238 — Upper Bucklandi Interval And Top Of The Blue Lias Formation
Beds 203–238 represent the upper part of the Bucklandi interval and the formal top of the Blue Lias Formation in modern BGS lithostratigraphy. Mudstones remain predominant, in part fissile and bituminous, with limestones, some laminated, at frequent intervals. Macrofossils become locally more diverse upward, with epifaunal and shallow-infaunal bivalves, rhynchonellid and terebratulid brachiopods, gastropods, serpulids and vertebrate remains. The top of Bed 238 is the lithostratigraphic point at which persistent Blue Lias limestone rhythms give way to the more mudstone-dominated Charmouth Mudstone Formation.
Charmouth Mudstone Formation (Lower Sinemurian)
In older west Somerset literature the numbered beds continue seamlessly above the Blue Lias, and those published bed numbers are retained here because they remain the practical field scheme for placing Quantoxhead within the wider coastal succession. Under current BGS lithostratigraphy, however, Beds 239 upward belong to the basal Charmouth Mudstone Formation rather than the Blue Lias.
Beds 239–244 — Basal Charmouth Mudstone Still Within The Bucklandi Zone
The lowest Charmouth Mudstone beds are still within the Bucklandi Zone in Page’s interpretation, showing that the ammonite zonation does not coincide exactly with the modern formation boundary. The lithology becomes more mudstone-dominated and the limestone beds less regular and less laterally persistent than in the Blue Lias below, but deposition remained fully marine and offshore. This interval is transitional in field appearance: still recognisably lias in style, yet no longer the classic evenly rhythmic Blue Lias.
Beds 245–257 — Higher Lower Sinemurian Mudstones, Probably Lyra Subzone In Part
Above the Bucklandi interval, about 50 m of largely mudstone-dominated succession continues upward to Bed 257, with only a few mostly nodular limestones. Page assigned this higher part of the succession to the Lyra Subzone and recognised distinct ammonite horizons in correlative west Somerset sections, but the higher lower Sinemurian subzonal sequence at Quantoxhead is much less securely proved than the boundary interval below. These beds are therefore best treated conservatively as basal Charmouth Mudstone of higher lower Sinemurian age rather than as a fully settled bed-by-bed zonal sequence.
Structural Style
The Quantoxhead coast is not a single flawless vertical reference face. Across the wider Blue Anchor–Lilstock coast the succession is interrupted by both normal and reverse faults, and local repetition or omission of shale intervals is real, especially eastward toward Lilstock. Even so, the boundary interval north of East Quantoxhead is exposed over a long stretch of cliff and foreshore and individual limestone markers can be traced well enough for a robust composite log. This is why the section works so well as an international stratotype even though the wider coast is structurally complex.
Stratigraphic Significance
Within about 27 m of strata, from the upper Complanata Subzone to the lower Rotiforme Subzone, fifteen distinct ammonite biohorizons have been recognised. That level of resolution, together with the unique overlap of Schlotheimia and the earliest arietitids in Bed 145 and the supporting foraminiferal changes above the boundary, is why Quantoxhead functions as the world standard for the base of the Sinemurian Stage.
Depositional Environment
The Quantoxhead succession was laid down in a fully marine shelf basin within the Bristol Channel–Central Somerset basin system. Repeated Blue Lias cycles of bituminous shale, marl, limestone and marl reflect alternation between quieter, more organic-rich mud accumulation and more oxygenated carbonate-rich phases. Laminated paper shales indicate reduced bottom-water oxygenation, locally reaching dysoxic or anoxic conditions, whereas the limestones and bioturbated mudstones record intervals of better benthic activity. Rapid subsidence explains both the unusual thickness of mudstone at Quantoxhead and the exceptional completeness of the ammonite record.
Preservation And Typical Fossils
Collector and research value at Quantoxhead lies not just in the ammonites but in the style of preservation. Ammonites from laminated organic-rich mudstones can retain iridescent aragonite, whereas shells in limestones are commonly more three-dimensional. Typical fossils through the wider regional succession described above include Psiloceras, Caloceras, Waehneroceras, Schlotheimia, Vermiceras and Metophioceras, together with oysters such as Liostrea hisingeri, gryphaeids, pectinids, brachiopods, serpulids, echinoids, fish remains and occasional ichthyosaur material.
Total Thickness Covered Here
In the regional Somerset framework, the formal Blue Lias Formation extends from the base of the Lias to the top of Bed 238. Older west Somerset measured successions continue the published numbered bed scheme upward to Bed 257, now classed as basal Charmouth Mudstone Formation. Quoted total thicknesses for the numbered lower Lias succession vary because of faulting, correlation differences and later lithostratigraphic revision: Palmer recorded about 178.9 m, whereas Whittaker & Green recorded about 203 m. For website use, it is best to treat Quantoxhead as a thick composite Hettangian–lower Sinemurian coast section rather than to force a single spurious total for one small cliff face.
References
Palmer, C.P. (1972) on the Lower Lias succession between Watchet and Lilstock, west Somerset.
Whittaker, A. & Green, G.W. (1983). Geology of the Country around Weston-super-Mare.
Warrington, G. & Ivimey-Cook, H.C. (1995) on the Penarth Group and basal Lias of coastal west Somerset.
Hodges, P. (1994) on the lowest Jurassic ammonites in west Somerset.
Page, K.N. & Bloos, G. (1998) on the basal Hettangian ammonite succession of west Somerset.
Bloos, G. & Page, K.N. (2000, 2002) on the Hettangian–Sinemurian boundary succession and the Global Stratotype Section and Point at East Quantoxhead.
Page, K.N. (1992, 1994, 2001, 2002) on Sinemurian ammonite biohorizons and the Quantoxhead boundary interval.
Page, K.N. and co-authors (2000) on the East Quantoxhead Sinemurian GSSP proposal.
Hylton, M.D. (1998) on foraminiferal changes across the Hettangian–Sinemurian boundary at East Quantoxhead.
British Geological Survey Lexicon: Blue Lias Formation and Charmouth Mudstone Formation.
JNCC Geological Conservation Review account: Blue Anchor–Watchet–Lilstock Coast.
International Commission on Stratigraphy GSSP register: base of the Sinemurian Stage, East Quantoxhead.
ICS: Sinemurian GSSP, East Quantoxhead
Bloos & Page (2002), Sinemurian GSSP
GCR30: Blue Anchor–Lilstock coast
BGS Lexicon: Blue Lias Formation
SAFETY
Common sense when collecting at all locations should be used and knowledge of tide times is essential. You can easily be cut off at Quantoxhead by the tide as the sea always reaches parts of the cliff. The cliffs are very unstable, undercut and rocks are frequently crashing down. Keep away from the base of the cliff at all times.
EQUIPMENT
Quantoxhead covers a huge area and there is lots of walking to be done. The rocks are actually much less fossiliferous than other Lower Lias locations, but the huge area makes finds just as frequent. Whilst most fossils can be collected loose without any tools, We recommend a lump hammer, chisel, goggles and gloves for any large blocks.
CLEANING AND TREATING
Begin by removing any loose sediment very carefully using a soft toothbrush. Take your time, as many fossils—particularly pyritic specimens—are fragile and easily damaged. Once cleaned, fossils should be desalinated by soaking them in fresh water for at least 24 hours to remove residual salt. After soaking, allow specimens to dry naturally at room temperature. Do not dry them on radiators or other heat sources, as rapid drying can cause cracking or long-term damage.
Once fully dry, we recommend sealing fossils with Paraloid B-72, dissolved in acetone. This is a museum-grade consolidant that is widely available in pre-mixed bottles. Paraloid B-72 is stable, long-lasting, and does not yellow or react chemically over time. Importantly, it is also fully reversible, making it suitable for scientifically important or display-quality specimens.
Some collectors prefer to treat ammonites with artists’ varnish. This is acceptable for common species that are not of scientific importance, as it enhances colour and contrast and can make a specimen really “pop”. However, varnish is not reversible and is therefore not recommended for rarer or research-grade fossils.
IDENTIFY YOUR FINDS
Need help identifying a fossil? Share clear photos, where you found it and its size with the community.
FURTHER READING
Deposits Magazine – Fossils of the West Somerset coast (regional coast overview)
International Commission on Stratigraphy – GSSP for the Sinemurian Stage
GCR / GeoGuide – Blue Anchor–Lilstock Coast, Somerset (regional stratigraphy)
Watchet Market House Museum – Fossils of the Watchet-area coast (regional collection)
ACCESS RIGHTS
This site is an SSSI. This means you can visit the site, but hammering the bedrock is not permitted. For full information about the reasons for the status of the site and restrictions please download the PDF from Natural England – SSSI Information
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
