Kilve’s limestone reefs and dark Jurassic shale reveal ammonites, changing seafloor conditions and remarkable ancient methane-seep structures. The shore east of Kilve Pill is the main route described here, with loose fossil material and exposed pavements to examine carefully on a falling tide while protecting the cliffs and embedded finds.
FIND FREQUENCY: ♦♦♦ – Ammonites and shell remains occur in particular beds; shale specimens are often flattened and fragile. Reptile remains are notable, uncommon finds.
CHILDREN: ♦♦♦ – Supervised families can enjoy the beach, but slippery reefs, rising water and unstable cliffs require constant care.
ACCESS: ♦♦♦ – A short signposted walk leads from the private Sea Lane car park to the shore. Mud, uneven ground and tides can limit access.
TYPE – Cliffs and rocky foreshore with Blue Lias limestone, marl and shale; some fossils are best photographed in place.
DIRECTIONS
♦ Leave the A39 at Kilve and follow Sea Lane towards the coast. The lane has no pavement, so drive slowly and watch for walkers, horses and other road users.
♦ A privately operated pay-and-display car park lies at the end of Sea Lane. Check the signs for current charges and conditions; Kilve Parish Council does not operate it. Toilets and refreshments are available nearby, subject to their opening arrangements.
♦ Follow the current signed public route from the car park to Kilve Pill and the beach. The original guide’s shore reference is 51.19359°N, 3.22495°W. From the Pill, the main described fossil shore runs east towards the limestone and shale exposures.
♦ East Quantoxhead lies west of Kilve, while Lilstock lies east and north-east. These are separate coastal stretches; reaching a named bed farther along the shore requires its own route and tide planning.
♦ Visit on a falling tide with enough time to return. Check local tide, weather and wave conditions and identify the usable return path before walking beneath any cliff section.
FOSSIL HUNTING
Look first at naturally weathered surfaces and loose stones on the open foreshore. Blue-grey limestone often reveals shells or ammonite sections as pale outlines, while dark shale may preserve flattened coils and fine ribs. Oblique light and a little natural surface moisture can make the detail clearer. Avoid trampling or trying to extract the large flattened ammonites on the pavements: their shape can be impressive in place but extremely fragile once disturbed.
The ammonite fauna changes through the succession. Vermiceras and Coroniceras-group ammonites are supported in the local lower Sinemurian beds. Older Hettangian beds also occur on faulted parts of the outer foreshore and farther along the Kilve–Lilstock tract, with Caloceras recorded in upper Planorbis Zone intervals. A flattened ammonite beside Kilve Pill should not automatically be labelled Psiloceras planorbis; preservation and the bed or source rock matter.
Loose limestone blocks can preserve more three-dimensional material because carbonate cement formed before strong compaction. That does not make every nodule worth breaking. Examine its weathered edges for shell or bone, photograph it and follow the local collecting code and landowner conditions. The code favours only a few representative specimens from loose material or fallen blocks, with large fossils usually left for others to see. Do not hammer cliffs or work beneath unstable faces.
Marine reptile remains are recorded, including the famous Kilve ichthyosaur with a tiny associated embryo. Such exceptional specimens explain the coast’s scientific importance, but do not mean vertebrae are as common as ammonites or that reptile fossils are exempt from collecting restrictions. Bone can appear as a dark, textured fragment with internal porous structure, although weathered rock and mineral growth can be misleading. Photograph a possible important find with a scale, record its exact position and seek museum advice before attempting recovery.
The low conical limestone mounds east of the Pill deserve particular care. They are ancient carbonate-cemented seep structures, with fossils and sediment relationships that record methane escape from the Jurassic seafloor. Small three-dimensional ammonites, foraminifera, sparse bivalves and crinoid debris have been documented in parts of them, but much of the surrounding shale is poor in bottom-dwelling animals. Leave the mounds intact and examine them through photographs and a hand lens.
Keep fossil groups and rock types associated with their actual find places. Faults repeat and juxtapose different levels, and a walk eastwards is not a simple ascent through every numbered bed. Loose pieces may also have moved along the beach. Record whether a fossil was in place or loose, retain a small amount of attached matrix when removal is permitted, and avoid assigning a precise bed number from a general beach coordinate alone.
Collect sparingly within permission and keep any authorised fragile shale supported flat. Interesting fossils still fixed in a reef are often more useful as a photograph and location record than as damaged fragments. Report unusual or substantial finds to an appropriate museum rather than removing them without a plan.
Significant discoveries, research and conservation milestones at Kilve
1916 – Oil-rich shale recognised
Mining engineer J. Berry noted the bituminous shale at Kilve, leading to later interest in extracting oil.
Around 1924 – Oil retort built
A retort and experimental oil-extraction venture were established. The Geological Survey records production of several hundred barrels before financial difficulties ended the scheme.
1971 – Coast notified as an SSSI
The coast including Kilve was notified for its scientific importance, with several distinct geological interests protected along the wider shore.
1972 – Kilve Shales named in a coastal study
C. P. Palmer used the name Kilve Shales for division D in his detailed Watchet–Lilstock stratigraphy. The term describes a historical interval rather than a securely formalised modern member.
1983 – Survey documents beds and structures
Whittaker and Green published the local bed logs, faults, lateral changes and bell-shaped limestone mounds in the Weston-super-Mare memoir.
16 November 1984 – Oil retort listed
The surviving retort building received Grade II protection as a reminder of the short-lived oil-shale industry.
1985 – Ichthyosaur with associated embryo found
A well-preserved adult Ichthyosaurus with a tiny associated embryo was found near low-water mark at Kilve, around ST 144 447, in Johnstoni Subzone beds. This outer-foreshore find belongs to older strata than the Sinemurian seep mounds.
1986 – SSSI notification renewed
The Blue Anchor to Lilstock Coast designation was renewed under the Wildlife and Countryside Act 1981, with notification to the Secretary of State on 22 December.
24 January 1991 – Museum acquisition supported
The National Heritage Memorial Fund awarded £10,000 to Bristol City Council and Bristol Museum and Art Gallery towards acquisition of the Kilve ichthyosaur with unborn young.
1991 – Veins and faults compared
D. C. P. Peacock used Kilve coastal examples to investigate displacement, linkage and relationships between vein bridges and fault relay structures.
1993 – Embryo described scientifically
Deeming, Halstead, Manabe and Unwin described the adult-and-embryo association, interpreting the tiny skeleton as a mid-gestation embryo.
1995 – Fault and vein scaling studied
Bowyer and Kelly quantified Kilve structures and their strain relationships, examining extension followed by contraction or inversion.
2003 – Dome structures investigated as fluid escape
Cornford analysed the Kilve domes as mud-volcano or fluid-escape features, an interpretation subsequently refined by further stratigraphic and geochemical work.
2004 – Ammonite correlation revised
The Lower Jurassic GCR synthesised the coast and revised the subzonal framework relevant to Kilve, including uncertainty in correlation around Beds 224–225.
2008 – Methane-related carbonate demonstrated
Allison, Hesselbo and Brett studied early cementation and methane-derived carbonate. Independently, Price, Vowles-Sheridan and Anderson investigated mud-volcano carbonate and microfauna.
2014 – Limestone layers and fractures investigated
Afşar, Westphal and Philipp investigated how differences between limestone beds and their later cementation influence fractures. Work on the Kilve limestone–marl layers contributed to understanding these relationships.
2017 – Black shale and seepage linked to environmental cycles
Xu and colleagues used the 15.6 m Kilve section, carbon isotopes and pollen/algal evidence to investigate orbitally paced environmental changes and later methane seepage.
30 July 2026 – Seep chemical conditions reassessed
Wu and colleagues analysed Kilve and Ravenscar seep material using iron, trace-metal and isotope evidence, refining interpretations of anoxic conditions and microbial methane oxidation within seep systems.
GEOLOGY
The shore exposes the Blue Lias Formation of the Lias Group, a succession of limestone, marl and shale laid down in Early Jurassic seas. The main logged beds at Kilve include upper Hettangian and lower Sinemurian intervals. The alternating hard and soft layers produce the stepped reefs and low cliffs, while differences in early cementation and later compaction strongly affect the fossils.
Fine carbonate mud formed the pale limestone beds, while changes in sediment supply, organic matter and bottom-water conditions produced marls and dark shale. Some shale is finely laminated and contains little evidence of animals mixing the sediment. Ammonites in these soft beds were commonly flattened, whereas early-cemented limestone could protect a shell or small fossil in three dimensions. The contrast reflects preservation as well as the animals originally present.
The informal name Kilve Shales has been used for a shale-rich interval, but it is not treated here as a formally defined member. A modern research section east of Kilve Beach sampled 15.6 m of lower Sinemurian beds in the Rotiforme Subzone. Within it, an approximately 2 m organic-rich black shale lies 3.7–5.5 m above the study’s own datum. Those figures describe one sampled section, not the entire thickness of the Blue Lias or every shale exposure at Kilve.
The conical mounds formed when carbonate cement developed near the seafloor before the surrounding sediment was fully compacted. Geochemical studies support methane-related cementation and investigate how organic-rich sediment, microbial activity and changing environmental conditions were linked. The mounds should not be confused with ordinary reef-building coral colonies. Their fossils and shapes preserve a local seafloor environment, while newer work examines chemical conditions within the seep system itself.
The rocks have also been folded, faulted and cut by mineral veins. BGS describes mainly southward to south-south-westward dips east of Kilve, alongside many roughly east–west faults and local fold closures. These structures repeat parts of the succession and can place beds of different ages beside one another. The landscape cannot be explained by one uniform eastward dip towards East Quantoxhead, which actually lies west of Kilve.
The immediate east-of-Pill composite includes numbered beds 69–224 in the Survey account, but the detailed published figures draw different portions from different local exposures. Exact thicknesses from Park Farm, west Lilstock, Hinkley Point or Quantock’s Head cannot simply be transferred into the Kilve section. The expanded geology preserves the local bed descriptions, the separate sampled seep logs and the revised ammonite-zone correlations without treating the coast as one uninterrupted face.
Detailed geology, local numbered beds and separately measured Kilve research sections
The principal scope is Kilve Pill and the cliffs and foreshore immediately east of it. The Survey describes a composite numbered interval from Bed 69 to Bed 224 between approximately ST 1470 4461 and ST 1513 4464. Faulting, tides and discontinuous exposure mean that it is not one continuous face or a simple bed-by-bed walking route. The local Survey figures, separate modern research logs and neighbouring comparison sections have different geographical and measurement limits.
LIAS GROUP
Blue Lias Formation
Limestone, marl and shale record Early Jurassic marine deposition. The relevant local succession includes upper Hettangian and lower Sinemurian rocks. Kilve Shales is an informal historical interval rather than a securely defined formal member.
Ammonite zones and revised correlation. The 2004 GCR places the upper part of Bed 145 through 164 in the Conybeari Subzone, 165–202 in the Rotiforme Subzone and 203 to approximately 244 in the Bucklandi Subzone of the Bucklandi Zone. Higher beds beyond approximately 244 enter the Lyra Subzone of the Semicostatum Zone. This supersedes the older placement of Semicostatum near Beds 209–224. A supposed local Agassiceras record was revised to Coroniceras cf. kridion. The exact continuity around Beds 224–225 remains uncertain.
Local Survey bed descriptions, oldest upwards. The immediate-Kilve figures distinguish the following limestone beds, mudrocks and fossil-rich horizons. Some intervening mudrocks have no printed number; their position within the numbered succession is made explicit. Grouped numbers remain grouped where the source does not separate them. A numbered package can contain more than one limestone layer, separated by mudrock.
Beds 69–115: local lower column. Survey Figure 16, column D, describes the lower Kilve cliff-and-foreshore succession. The exact numerical thicknesses tabulated at Park Farm and west Lilstock belong to different exposures and are not transferred to these beds.
Bed 69. Tabular limestone at the base of the illustrated Kilve column.
Intervening position 70 (unlabelled in the figure). Mudrock separating limestones 69 and 71; number not printed in this column but enclosed within the published numbered succession.
Bed 71. Thin tabular limestone.
Intervening position 72 (unlabelled in the figure). Mudrock between 71 and 73; number not printed.
Bed 73. Wavy/nodular limestone band.
Intervening position 74 (unlabelled in the figure). Mudrock between 73 and 75; number not printed.
Bed 75. Irregular/wavy limestone bed.
Bed 76. Relatively thick mudrock interval, with an isolated limestone nodule in its lower part.
Bed 77. Tabular limestone.
Bed 78. Mudrock with several nodular/lenticular limestone levels and tabular limestone bands; it is not uniformly shale.
Bed 79. Limestone-rich package of tabular, wavy and lenticular/nodular limestones separated by mudrocks.
Intervening position 80 (unlabelled in the figure). Mudrock interval above the 79 package and below 81; not separately labelled in the graphic.
Bed 81. Discontinuous limestone nodules/lenticles.
Bed 82. Thicker mudrock interval with an isolated calcareous nodule near its top.
Bed 83. Limestone band with a thin internal parting/lateral subdivision.
Bed 84. Mudrock interval.
Bed 85. Limestone with irregular/nodular lower part.
Bed 86. Mudrock containing an isolated nodule.
Bed 87. Paired limestone bands, the lower wavy/nodular and the upper tabular, separated by mudrock.
Bed 88. Thicker mudrock interval.
Bed 89. Mixed package: discontinuous nodules near base and wavy limestone bands higher, with mudrock between.
Bed 90. Mudrock with isolated limestone nodule.
Bed 91. Thin tabular limestone.
Bed 92. Mudrock with a conspicuous lenticular/nodular limestone course.
Bed 93. Wavy limestone band.
Bed 94. Mudrock interval.
Bed 95. Two prominent limestone bands, one with wavy/nodular morphology, separated by mudrock.
Bed 96. Mudrock interval.
Bed 97. Closely spaced thin tabular limestone bands/parting.
Bed 98. Mudrock with an isolated calcareous nodule.
Bed 99. Multi-bed limestone-rich package with tabular and nodular/lenticular bands and intervening mudrock.
Intervening position 100 (unlabelled in the figure). Short mudrock interval between package 99 and 101; not explicitly numbered in this column.
Bed 101. Upper tabular and lower discontinuous/nodular limestone separated by mudrock.
Bed 102. Mudrock interval.
Bed 103. Tabular limestone.
Intervening position 104 (unlabelled in the figure). Mudrock parting between 103 and 105; not explicitly numbered in this column.
Bed 105. Tabular limestone.
Bed 106. Mudrock interval.
Bed 107. Thin tabular limestone.
Intervening position 108 (unlabelled in the figure). Mudrock parting between 107 and 109; not explicitly numbered.
Bed 109. Tabular limestone.
Intervening position 110 (unlabelled in the figure). Mudrock interval between 109 and 111; not explicitly numbered.
Bed 111. Tabular limestone.
Beds 112–113. Mudrock and a discontinuous nodular/lenticular limestone course; source groups the two numbers.
Bed 114. Tabular limestone.
Bed 115. Mudrock forming the top of this illustrated local lower column.
Intervening Beds 116–154. These belong to the Survey’s overall local interval 69–224, but the immediate-Kilve lower figure ends at 115 and the higher detailed local column starts at 155. A complete individual-bed description cannot be assembled from those local graphics alone. Correlative measurements at Park Farm and west Lilstock remain separate; this is not a demonstrated geological unconformity.
Beds 155–194: east-Kilve upper column. Survey Figure 15 supplies the following local descriptions, including the shell-rich horizons and the mound-bearing interval. Fossil symbols identify a concentration, not a species determination.
Bed 155. Tabular limestone.
Bed 156. Mudrock interval.
Bed 157. Thicker tabular limestone.
Bed 158. Mudrock interval.
Bed 159. Tabular limestone.
Bed 160. Mudrock interval.
Bed 161. Tabular limestone.
Bed 162. Mudrock interval.
Bed 163. Tabular limestone.
Bed 164. Thick mudrock interval.
Bed 165. Thicker tabular limestone.
Bed 166. Mudrock with a discontinuous limestone-nodule course.
Bed 167. Tabular limestone.
Bed 168. Mudrock interval.
Bed 169. Thin tabular limestone.
Bed 170. Thick mudrock interval.
Bed 171. Thin shell-rich horizon drawn at top of 170/below 172; glyphs represent fossils, not a separate thick limestone.
Bed 172. Mudrock interval.
Bed 173. Discontinuous nodular/lenticular limestone.
Beds 174–175. Thick mudrock package, carrying fossil glyphs towards its upper part; source groups these numbers.
Bed 176. Thin fossil-rich horizon at top of 174–175 package; the drawing does not establish a particular taxon.
Bed 177. Thin tabular limestone.
Bed 178. Thin mudrock interval.
Bed 179. Lenticular limestone tapering laterally.
Bed 180. Thick mudrock interval.
Bed 181. Wavy limestone band.
Intervening position 182 (unlabelled in the figure). Short mudrock interval between 181 and 183; number is not printed in the graphic.
Bed 183. Composite limestone package: lower lens pinches out laterally and an upper thin tabular limestone is separated by a narrow parting.
Bed 184. Mudrock interval between limestone package 183 and nodular limestone 185.
Bed 185. Nodular/lenticular limestone band.
Bed 186. Mudrock-dominated package with limestone nodules and a strongly up-arched limestone mass, the graphically encoded mound horizon.
Bed 187. Thin tabular limestone.
Bed 188. Mudrock with limestone nodules at several levels.
Bed 189. Thin tabular limestone.
Bed 190. Mudrock interval.
Bed 191. Mudrock interval above an internal subdivision of 190–191.
Bed 192. Thin tabular limestone.
Bed 193. Mudrock interval.
Bed 194. Discontinuous nodular/lenticular limestone.
Beds 195–212: Kilve cliff column. These descriptions use the Kilve portion of Survey Figure 16A. Its continuation above 212 uses Hinkley Point material and is not substituted for the local higher section.
Bed 195. Thick mudrock interval.
Bed 196. Tabular limestone.
Bed 197. Mudrock interval.
Bed 198. Mudrock package with a thin internal tabular limestone.
Bed 199. Two closely spaced tabular limestone bands with mudrock between.
Bed 200. Mudrock interval.
Bed 201. Discontinuous/lenticular limestone.
Bed 202. Mudrock interval.
Bed 203. Limestone nodules/lenticles at top of underlying mudrock.
Bed 204. Thick tabular limestone marker; also directly described as massive in cliff just west of Kilve Pill at ST 14224437.
Bed 205. Thick mudrock package with a nodular/lenticular limestone level and a higher thin tabular limestone band.
Bed 206. Tabular limestone.
Bed 207. Mudrock interval.
Bed 208. Thin tabular limestone.
Bed 209. Mudrock interval.
Bed 210. Tabular limestone.
Bed 211. Mudrock interval.
Bed 212. Tabular limestone.
Beds 213–224: separately documented local continuation. Survey Figure 14 supplies this Kilve portion. Its lower Quantock’s Head and higher Doniford/Helwell sections retain their own geographical scope.
Bed 213. Mudrock interval.
Bed 214. Thin tabular limestone.
Beds 215–216. Mudrock interval grouped in graphic.
Bed 217. Limestone band.
Beds 218–221. Thick mudrock interval grouped in graphic.
Bed 222. Tabular limestone.
Bed 223. Mudrock package with a thinner internal limestone band.
Bed 224. Tabular limestone capping the verified Kilve composite interval.
Measured lateral change east of Kilve. The Survey reports that its division 3 is about 7.6 m thicker east of Kilve beach than at Blue Ben, chiefly because the shale intervals thicken while the limestone beds remain broadly similar. Two Angulata-age limestones with irregular bases retain that feature eastwards. The 7.6 m is a difference between sections, not a total thickness of the Kilve exposure.
Research section: lower 0–3.7 m. Xu and colleagues sampled a 15.6 m section east of Kilve Beach at 51°11′39.4″N, 3°13′00.8″W, within the Rotiforme Subzone. Below 3.7 m on that study’s own datum, limestone and marly mudstone alternate and contain complete and fragmentary ammonites, bivalves and crinoids. The base lies close to the informal Kilve Shales base, but a bed-by-bed equivalence with every Survey number is not established.
Research section: black shale at 3.7–5.5 m. This approximately 2 m interval is finely laminated, rich in organic matter and shows little bioturbation, with few ammonites. Diplocraterion occurs near its top. Total organic carbon is reported at 5–11%, alongside a 2–3‰ negative excursion in organic-carbon isotope values. These measurements concern the study interval, not the whole formation, and the event is not the much younger Toarcian Oceanic Anoxic Event.
Research section: above 5.5 m to the 15.6 m top. Marl and shale alternate with occasional separate nodular limestones, with ammonites, bivalves and crinoids. Coalified wood fragments up to 10 cm occur through the sampled succession, especially the black shale. Carbon-isotope and pollen/algal changes were interpreted in terms of eccentricity-modulated, precession-paced environmental variation. The 15.6 m is a sampled exposure thickness, not the total Blue Lias or Kilve Shales thickness.
Methane-seep mounds. The structures around ST 1510 4462, also described near ST 1506 4463 in the 2014 excursion, lie approximately within Survey Beds 182–186 in the Rotiforme Subzone. The earlier Survey account placed the mounds broadly within Beds 166–188; the later approximately 182–186 placement is more narrowly defined. Allison and colleagues mapped four large conical mounds, 3–4 m across at the base and 1–1.5 m high, plus around ten smaller concretions. Early carbonate cementation allowed them to retain relief before burial compaction. Xu places the seep horizon approximately 5 m above the organic-rich shale in its local framework; that is distinct from the datum of the short log described next.
Smaller concretions and local mound relationships. The smaller bodies are 40 cm to 1 m across and no more than 40 cm thick, occurring about 1 m above the bases of the larger mounds. Their fine-grained matrix contains pebble-sized intraclasts; lamination preserved across some clasts indicates little movement after lithification. In mound 2, erosion had breached a 30 cm limestone layer to reveal black shale beneath. A separate concretionary limestone about 1 m below the mounds contains trace fossils. These are relationships within the mound-bearing exposure, not extra thicknesses to add to either research log.
Mound fossils and interpretation. Small three-dimensional ammonites, many less than 1 cm across, Involutina, sparse bivalves and disarticulated crinoids occur particularly in the crater of mound 1. Allison’s bivalves were not identified more precisely. Much of the enclosing black shale and most mound surfaces contain few benthic animals. Methane-derived cement, probably linked to microbial generation in organic-rich sediment, is supported geochemically; locally oxygenated benthic patches were proposed, but a chemosynthetic community was not demonstrated.
Price and colleagues independently studied three mud-volcano structures, describing carbonate caps, mud breccia, crinoids and abundant Involutina liassica. Three studied structures need not equal the four larger mounds mapped by Allison. Cornford’s earlier fluid-escape interpretation is part of the research history, but its Angulata/C115 correlation and deeper-pressure model differ from later stratigraphic and geochemical interpretations.
Allison’s approximately 5 m sampled micro-section. Figure 6 distinguishes limestone, dark marl and laminated shale using its own local height datum. The sample positions below are heights above that datum, not bed thicknesses, and are not directly interchangeable with Xu’s 3.7–5.5 m black-shale interval. Mound bases lie at roughly 2.7 m on this graphic’s scale.
KP1, approximately 0.46 m. The plotted sample is from limestone.
KP2, approximately 0.62 m. The plotted sample is from shale.
KP3, approximately 0.72 m. The plotted sample is from a limestone or nodular lens.
KP4, approximately 0.87 m. The plotted sample is from shale.
KP5, approximately 1.12 m. The plotted sample is from a thicker limestone.
KP6, approximately 1.38 m. The plotted sample is from shale.
KP7, approximately 1.62 m. The plotted sample is from shale.
KP8, approximately 1.70 m. The plotted sample is from a limestone or concretionary interval with body- and trace-fossil symbols.
KP9, approximately 2.00 m. The plotted sample is from limestone.
KP10, approximately 2.25 m. The plotted sample is from shale.
KP11, approximately 2.55 m. The plotted sample is from limestone.
KP12, approximately 2.80 m. The plotted sample is from limestone.
KP13, approximately 3.05 m. The plotted sample is from shale.
KP14, approximately 3.13 m. The plotted sample is from limestone.
KP15, approximately 3.40 m. The plotted sample is from shale.
KP16, approximately 3.60 m. Table 1 records a sample from sediment matrix associated with the pebble bed.
KP17, approximately 3.68 m. The plotted sample is from limestone.
KP18, approximately 4.38 m. The plotted sample is from a concretion.
KP19, approximately 4.53 m. The plotted sample is from shale.
KP20, approximately 4.78 m. The plotted sample is from limestone.
Specimen-scale transect through mound 1. A polished slab from the limestone at mound 1’s crater or apex was sampled separately from the coastal section. Table 1 and Figure 7 use millimetres above a datum within that specimen. They do not describe fifteen coastal beds or extend the approximately 5 m or 15.6 m research logs.
In sample-number order, the positions are KL3b/1 at 74 mm, /2 at 67 mm, /3 at 60 mm, /4 at 54 mm, /5 at 56 mm, /6 at 50 mm, /7 at 45 mm, /8 at 41 mm, /9 at 35 mm, /10 at 30 mm, /11 at 23 mm, /12 at 18 mm, /13 at 13 mm, /14 at 5 mm and /15 at 0 mm. Sample 1 is brown mud above the crust; samples 2 and 5 are straw-brown spar within it; samples 3, 4, 6, 7 and 8 are dark-brown sediment or cement in the crust. Samples 9–15 are grey sediment below the crust, with sample 13 specifically from dyke or septarian material. Sample numbers therefore need not progress monotonically in height.
A separate set from other concretionary material comprises pebble samples KL2/1–3 and matrix samples KL2/4–5. No heights are assigned to these five samples in the published table.
Recent seep geochemistry. Wu and colleagues’ 2026 study examined Kilve and Ravenscar samples separately using iron speciation, trace metals and carbon/sulphur isotopes. Their results support predominantly iron-bearing anoxic conditions within the seep systems and microbial sulphate-driven methane oxidation, in part under sulphate limitation. These are inferences about seep and pore-water environments, not proof that the entire Bristol Channel water column was uniformly anoxic.
Faults, folds and repeated strata. East of Kilve, beds commonly dip south or south-south-west and are cut by faults trending approximately 100°. One fault has negligible displacement near ST 1481 4451 but increases to a reported 73 m throw at ST 1444 4457, placing Bucklandi against Planorbis beds. Another has at least 60 m throw near ST 1526 4467 and dies westwards within Liasicus strata near ST 1452 4467. These structural measurements explain juxtaposition; they are not bed thicknesses.
Studies of normal, reverse and strike-slip faults and mineral veins describe an early extensional history followed by contraction or inversion. Vein bridges, fault linkage and relay geometries can be compared, with an exact eastern Kilve vein example at ST 1481 4458. Not every structure described between Blue Ben and Kilve lies on the immediate east-of-Pill route.
Separate west-of-Pill and outer-foreshore observations. Massive Bed 204 is described in the cliff immediately west of Kilve Pill at ST 1422 4437. The west-side coast towards Quantock’s Head exposes additional parts of Beds 97–204. Planorbis-age rocks occur in faulted outer intertidal exposures, including north and east of the syncline near ST 1386 4437; these require their own tidal access and are not a single convenient outcrop beside the car park.
Eastward geographical variation. Upper Planorbis beds with Caloceras are recorded at ST 1538 4517 on the low-tide foreshore and ST 1571 4510 in cliffs farther towards Lilstock. Liasicus exposures include ST 1490 4470 and ST 1545 4506, with another farther east at ST 1667 4557. Angulata rocks are noted at ST 1510 4490 on the foreshore and ST 1540 4490 in cliffs, and low-dipping reefs occur farther towards Lilstock at ST 1615 4560. Bucklandi patches at ST 1495 4461, ST 1555 4525, ST 1588 4538 and ST 1656 4574 occupy progressively different eastern positions. These are separate geological stations, not a guarantee that every one can be reached during one tide.
Nearby older rocks and inland superficial deposits. Faulted Penarth and Blue Anchor slivers northwest or west of Kilve occur near ST 1376 4446, ST 1384 4465 and ST 1355 4448; they do not establish a full older-rock succession on the main eastern route. Inland in the Kilve valley, Head deposits contain Devonian sandstone clasts in sandy loam: up to 2.44 m near Chantry and 1.22 m over Lias in the stream bank at ST 1452 4422. Those are inland superficial observations and are not added to the coastal bedrock log.
Regional correlations and limits. East Quantoxhead and its Sinemurian boundary stratotype lie west of Kilve. The boundary positioned 0.9 m above the base of Bed 145 is measured at that separate site. Likewise, the Park Farm/west-Lilstock table for Beds 69–157, the Quantock’s Head section and the Hinkley Point higher beds remain comparative sections with their own thicknesses. The separately described KI1 research section at Kilve Pill uses its own lettered units, described next.
KI1 short section at Kilve Pill. Afşar’s textual description records limestone beds 12–16 cm thick, alternating with marl or shale interbeds 8–42 cm thick. Its unit C contains nodules; shaly unit D grades locally into semi-nodular unit E. These measurements and letters belong to that short research section, with a separate local framework. They are not individual thicknesses for the Survey-numbered beds, and the precise correlation between the two schemes is unresolved.
References.
Whittaker and Green (1983), Weston-super-Mare Geological Survey memoir, local sections and Figures 14–16.
Simms and colleagues (2004), Blue Anchor–Lilstock GCR, revised zonation.
Allison, Hesselbo and Brett (2008), methane seeps and sampled micro-section.
Xu and colleagues (2017), black shale and orbital pacing.
Wu and colleagues (2026), seep-system geochemistry.
Bowyer and Kelly (1995), Kilve faults and veins.
SAFETY
Kilve has a large tidal range, and incoming water can cut off stretches against the cliffs. Check the day’s local tide times, weather and swell, begin with a falling tide and turn back well before the return route becomes restricted. Do not rely on a phone signal to solve a tidal trap.
Stay well away from the cliff foot and fresh falls. Limestone blocks and shale faces can fail without warning, including in apparently calm weather. Do not climb the cliffs, hammer them or search directly beneath unstable rock.
Wet shale, seaweed, pools and tilted limestone ledges are slippery. Wear grippy footwear, supervise children closely and avoid wave-washed reefs. Paths and tracks can be muddy, and accessible facilities near the car park do not make the whole foreshore an accessible route.
EQUIPMENT
Bring current tide information, sturdy footwear, a charged phone, a camera, hand lens, notebook and small scale. Photography is the best way to record embedded pavement ammonites and the seep mounds.
If a few loose specimens may be removed under the applicable conditions, use soft wrapping and a rigid container. Support shale slabs flat and separate them from heavy limestone. Do not bring excavation equipment for the cliffs or protected mounds.
CLEANING AND TREATING
Record the exact locality and whether the piece was loose or in place before cleaning any authorised specimen. Shale ammonites can peel, crack or lose detail when scrubbed or soaked, so start with gentle dry removal of loose grit and support the whole slab.
Limestone matrix and calcitic fossils can be damaged together by acid, forceful splitting or uncontrolled power tools. Avoid household acids, bleach and varnish. Leave possible vertebrate remains, delicate fossils and unusual associations unprepared for specialist assessment; retain any counterpart and attached matrix.
IDENTIFY YOUR FINDS
Need help identifying a fossil? Share clear photos, where you found it and its size with the community.
FURTHER READING
Deposits: Fossils of the West Somerset coast (regional guide)
BGS Weston-super-Mare memoir: Kilve sections and structures
Geological Conservation Review: Blue Anchor to Lilstock Coast
Allison and colleagues: Early Jurassic methane seeps at Kilve
Xu and colleagues: Kilve black shale, carbon cycle and seepage
Wu and colleagues: chemical conditions in Early Jurassic methane seeps
Bowyer and Kelly: Kilve faults and veins
Quantock Hills: geology, fossils and collecting code
Quantock Hills: Kilve and East Quantoxhead walk
Natural England: Blue Anchor to Lilstock Coast SSSI citation
ACCESS RIGHTS
Kilve forms part of the Blue Anchor to Lilstock Coast SSSI. Its scientific designation protects a coast containing several distinct geological localities; it is neither a general collecting licence nor evidence that every loose fossil is subject to the same blanket prohibition.
Follow the Quantock Hills collecting code, current signs and landowner conditions. The published code allows only a few representative specimens from loose material or fallen blocks, prohibits hammering cliffs and calls for private-land permission, careful recording and reporting unusual finds. Leave large fossils and embedded pavements for others to see, preserve the seep mounds and do not collect beneath unstable cliffs. Reptile remains are not an automatic exception to these conditions.
It is important to follow our ‘Code of Conduct’ when collecting fossils or visiting any site. Please also read our ‘Terms and Conditions‘
LINKS
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♦ Fossil Articles
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♦ UK Fossils Network
