White Nothe Fossil Hunting

1876 – Barrois published one of the first major accounts of the Upper Cretaceous at White Nothe
Charles Barrois included White Nothe in his classic work on the Upper Cretaceous of England and Ireland. This early study helped establish the importance of the White Nothe cliffs for understanding the Chalk succession of Dorset and its relationship to other parts of southern England.

1901 – A. W. Rowe produced the classic zonal account of the Dorset White Chalk, including White Nothe
Arthur Wade Rowe’s work on the zones of the White Chalk of the English coast made White Nothe one of the important Dorset sections for Chalk biostratigraphy. His study helped place the exposed succession into the wider framework of Upper Cretaceous fossil zones used around the English coast.

1904 – Jukes-Browne and Hill included White Nothe in the classic Geological Survey account of the Cretaceous rocks of Britain
The great Geological Survey memoir on the Upper Chalk of England helped cement White Nothe as one of the standard Dorset coastal sections. This work contributed to the long scientific tradition of using White Nothe as a reference point in the Chalk succession.

1967 – Drummond clarified the Cenomanian palaeogeography of Dorset and the importance of White Nothe
P. V. O. Drummond’s work on Cenomanian palaeogeography showed that White Nothe is especially important for understanding condensed Chalk successions on the margin of the basin. His research helped explain the rapid overstep of the Chalk and the erosion beneath it in this part of Dorset.

1970 – the Mid-Dorset Swell concept highlighted White Nothe as part of an important tectonic and sedimentary transition zone
Drummond’s later work on the Mid-Dorset Swell reinforced the importance of White Nothe in showing how Albian and Cenomanian earth movements affected sedimentation. This made the locality significant not only for fossils, but also for reconstructing the tectonic history of the Dorset Chalk margin.

1979 – Mortimore’s work on erosional surfaces helped explain major sedimentary breaks seen at White Nothe
Research on the stratigraphy of the Chalk in southern England showed that White Nothe preserves evidence of important erosional and mineralised surfaces within the Chalk succession. These surfaces became central to understanding condensation, omission and erosion on the margins of the Chalk basin.

1996 – Gale used White Nothe in Turonian correlation and sequence stratigraphy of the Chalk
Later sequence-stratigraphic work showed that White Nothe is an important transitional section for correlating the Dorset Chalk with other successions in southern England. This helped reinforce the value of the site for tracing key marker beds, marl seams and fossil events through the Chalk.

1997 – Bristow, Mortimore and Wood formalised the Chalk lithostratigraphy used to map the White Nothe succession
Modern lithostratigraphic work provided the framework used for mapping the Chalk formations exposed at White Nothe, including the Zig Zag Chalk, Lewes Nodular Chalk, Seaford Chalk, Newhaven Chalk and Culver Chalk. This gave White Nothe an important place in the modern geological mapping of the Dorset coast.

Modern understanding – White Nothe is recognised as a key section for Chalk overstep, condensation and faunal change
Modern reviews recognise White Nothe as one of the most important Dorset sections for showing how Upper Cretaceous sediments and fossil assemblages change towards the margin of the basin. The site is particularly important for the condensed Cenomanian succession, the sub-Chalk erosion surface, and the way fossil abundances differ from the main basin farther east, with Holaster especially common in the Upper Cenomanian and regular echinoids more common in the Upper Turonian.

Bed WN1 — Jurassic Substrate And White Nothe Unconformity (context interval)

White Nothe must be treated as a composite structural locality, not as a single uninterrupted measured face. West of the headland and around Holworth House, Gault and Upper Greensand rest with marked unconformity on steeply dipping Portland Stone and Portland Sand, Purbeck lagoonal and peritidal strata, and locally the highest Kimmeridge Clay marine mudstone; the relationship is further complicated by the Holworth House Fault and by widespread landslip, so the Jurassic rocks are best regarded here as the faulted substrate beneath the Cretaceous overstep rather than as a continuous bed-by-bed foreshore log. On this page, the WN numbers used outside the White Nothe Member are site-use identifiers for major local lithological intervals; only Beds 1–18 below are formal published bed numbers.

SELBORNE GROUP

Gault Formation

Bed WN2 — Gault Formation (c. 12.5 m in the classic White Nothe measurement)

Strahan measured about 12.5 m of sandy clays and clayey sands at the base of the Cretaceous succession here. Lithologically the Gault is a pale- to dark-grey and locally blue-grey sandy mudstone/clay unit, glauconitic in part and originally containing phosphatic and pyritic nodules, but it is now usually poorly exposed because montmorillonite-rich beds fail easily and generate the undercliff. Its significance at White Nothe is stratigraphic rather than scenic: it records the marine flooding across an eroded Jurassic surface, and regional ammonite evidence from the local Gault–transition interval indicates late Albian ages including the spathi, intermedius and nitidus ammonite subzones, although in situ collecting is limited by poor exposure and slumping.

Upper Greensand Formation

Foxmould Member

Bed WN3 — Lower To Middle Foxmould Sandstones (most of the c. 30 m Foxmould succession)

The lower part of the Upper Greensand in the Isle of Purbeck is the Foxmould, a succession of fine-grained glauconitic sandstones with tabular calcareous beds and ovoid cementstones. At White Nothe the bulk of its c. 30 m thickness is concealed by landslip, but the member originally comprised weakly calcareously cemented green sands that coarsen upward from the Gault and become increasingly bioturbated and shelly higher in the section. The wider Foxmould fauna indicates late Albian ages from the orbignyi and binum ammonite subzones upward into the choffati–early auritus transitional interval, and White Nothe is one of the key Dorset localities showing how this sandy shelf succession was thinned and condensed on the Mid-Dorset Swell. Indigenous crushed Callihoplites have been recorded about 2 m below the Exogyra Rock, showing that fossiliferous late Albian beds persist high in the Foxmould even where exposure is poor.

Bed WN4 — Exogyra Rock (upper Foxmould interval; c. 2.95–3.15 m)

The uppermost Foxmould at White Nothe is the classic Exogyra Rock. The lowest c. 0.9 m is a glauconitic sandstone with patchy dense calcareous cement and traces of cross-bedding; above this lies c. 1.6–1.8 m of highly bioturbated green sandstone with calcareously cemented Thalassinoides, oysters and serpulids, commonly concentrated at the base on an irregular surface; the upper c. 0.45 m is a bioturbated calcareous glauconitic sandy limestone/sandstone with nodular texture and abundant Amphidonte obliquata (the old Exogyra conica of older literature), Rhynchostreon columba, Neithea fragments and serpulids. This is one of the most fossiliferous and collector-relevant Albian horizons at White Nothe and represents a shallow marine oyster-rich firmground immediately below the far more condensed White Nothe Member.

White Nothe Member

Published Bed Numbering Used Below

Beds 1–18 below are the published bed numbers of the White Nothe composite section used by Gallois & Owen for the highest Upper Greensand; they are not a website renumbering. The member, formerly included in the local ‘Chert Beds’, consists of laterally variable calcareous sandstones, sandy calcarenites and highly glauconitic sandstones separated by up to eight erosional hardgrounds, some locally sheared out. In the modern log all sandstones are fine-grained and glauconitic unless otherwise stated, and fresh colours range from dark green in the most argillaceous beds to faintly green-tinged off-white in the hardest calcarenites. Fossils are less diverse than in the Foxmould but include exogyrine oysters, pectinids, serpulids such as Rotularia concava, brachiopods, echinoids and the famous phosphatised ammonite assemblage of Bed 5.

Bed 1 — Basal Dark-Green Glauconitic Sandstone On Hardground (c. 0.6 m)

Dark green, fine-grained, highly glauconitic sandstone resting on a hardground surface. It is bioturbated and locally shows wavy to streaked bedding, common shell chips, serpulids and a few exogyrid oysters, with sheared off-white calcareous sandstone lenses in its upper part. This bed records renewed sandy sedimentation after a firmground interval, and the mixture of shells, glauconite and disrupted bedding suggests low sediment accumulation on a shallow marine shelf repeatedly affected by winnowing and burrowing.

Bed 2 — Pale Cemented Sandstone And Sandy Calcarenite With Mineralised Top (c. 0.5 m)

Very pale grey sandstone and sandy calcarenite, densely cemented, passing down into Bed 1 but capped by a mineralised hardground. Its resistant lithology makes it a useful marker, and the early cementation shows that deposition paused long enough for firmground development and mineralisation before the next glauconitic sand pulse.

Bed 3 — Burrowed Calcareous Glauconitic Sandstone (c. 0.7–0.9 m)

Fine-grained calcareous and argillaceous glauconitic sandstone cut by ramifying off-white weathering silicified tubular and thalassinoid burrows. The strong contrast between dark green sandstone and pale burrow-fill reflects both intense bioturbation and selective silicification. Fragmentary ammonites have been reported from low in the White Nothe Member around this level, so Bed 3 is important both as a marker bed and as part of the lower fossil-bearing condensed interval.

Bed 4 — Nodular Calcarenite And Cemented Sandstone (c. 0.3–0.5 m)

Calcarenite and densely cemented calcareous sandstone with a nodular fabric produced by bioturbation, cementation and downward sand-filled burrows from the bed above. The irregular transition from Bed 3 shows that lithological boundaries here commonly coincide with burrow overprinting rather than simple primary bedding. It represents another strongly condensed, early-cemented shallow marine bed.

Bed 5 — Ammonite Bed (c. 0.55 m)

Dark to very dark green argillaceous sandstone, highly bioturbated and complexly bedded, with abundant whole and fragmentary calcitic shells, brown phosphatised bivalves and ammonites, scattered black phosphorite clasts, marcasite concretions and reworked sandstone clasts in the lower part. This is Arkell’s classic Ammonite Bed and one of the most important fossil horizons at White Nothe. The ammonite assemblage, including forms such as Callihoplites, Pleurohoplites, Discohoplites, Stoliczkaia, Durnovarites, Lepthoplites and numerous heteromorphs, indicates condensation around the perinflata and early briacensis subzones, with gentle winnowing and repeated reworking on an omission surface.

Bed 6 — Laminated Glauconitic Sandstone Above Hardground (c. 0.1–0.3 m)

Mid-green, argillaceous, highly glauconitic sandstone with distinctive planar and wavy lamination and only limited chert development. Because burrowing is less destructive here than in many adjacent beds, primary lamination survives more clearly and shows deposition as a very thin sand drape above another hardground. Small chert clasts and concretions disturb the laminae locally.

Bed 7 — Nodular Calcarenites With Cherts And Siliceous Concretions (c. 0.5–0.6 m)

Complexly bioturbated nodular calcarenites and densely cemented calcareous sandstones with small to large cherts and siliceous concretions. This is one of the most laterally variable beds in the member, changing noticeably over short distances as cemented patches, chert bodies and burrow systems expand or pinch out. It is best interpreted as a hardground-prone condensed carbonate-sand interval developed on a shallow, intermittently starved sea floor.

Bed 8 — Thin Argillaceous Glauconitic Sandstone On Hardground (c. 0.1–0.2 m)

Fine-grained argillaceous glauconite-rich sandstone with wavy lamination and siliceous burrow-fills, resting directly on a hardground. Its thinness and sharp boundaries suggest deposition during a short-lived renewal of sand supply between longer phases of non-sequence and early cementation. The bed is useful in correlation because it separates two more massive cemented units.

Bed 9 — Interbedded Cemented Sandstones And Lenticular Cherts (c. 0.35–0.45 m)

Irregularly interbedded calcareously cemented glauconitic sandstones and lenticular cherts, including chertified burrow infillings. The irregular geometry of the chert bodies, together with the burrow-controlled silicification, makes this one of the most distinctive siliceous intervals in the White Nothe Member. It records strong early diagenetic redistribution of silica in a heavily bioturbated substrate.

Bed 10 — Burrowed Calcareous Glauconitic Sandstone (c. 0.45 m)

Fine-grained calcareous glauconitic sandstone cut by ramifying off-white weathering silicified tubular and thalassinoid burrows, with a locally very glauconite-rich basal seam. The sharp burrowed contact above a hardground shows rapid recolonisation of the sea floor after another break in deposition. Lithologically it is a classic White Nothe bed: green glauconitic sand below, pale silicified burrow networks above, and a strongly condensed shelf signature throughout.

Bed 11 — Thin Glauconite-Rich Sandstone (c. 0.2–0.25 m)

A thin glauconite-rich sandstone sheet separating more strongly cemented units. Although simple compared with the beds above and below, it is important because it represents background sand deposition between two phases of carbonate cementation and omission. In the field it helps to pick out the upper part of the member where individual beds are closely stacked and easy to confuse.

Bed 12 — Pale Sandy Calcarenite With Poikilitic Cement (c. 0.05–0.2 m)

Very fine sandy calcarenite with poikilitic cement, pale off-white to faintly green-tinged, densely cemented and tabular, with gently undulating upper and lower surfaces. This is a hard, carbonate-rich marker bed and one of the clearest signs that calcareous cementation periodically dominated over clastic input in the upper part of the member. Its pale colour contrasts strongly with the darker glauconitic sands immediately adjacent.

Bed 13 — Thin Glauconitic Sandstone Sand Parting (c. 0.05–0.1 m)

A very thin, fine-grained glauconite-rich sandstone with a sharp, gently undulating base. It acts as a sand parting between harder calcarenitic beds and probably represents a brief return to clastic sedimentation after cementation of Bed 12. Its very small thickness is itself evidence of extreme condensation.

Bed 14 — Silicified-Burrow Glauconitic Sandstone (c. 0.2–0.3 m)

Fine-grained calcareous glauconitic sandstone cut by off-white silicified tubular and thalassinoid burrows, becoming more glauconitic downward. The burrow systems are conspicuous and locally make the bed appear mottled or tubular in section. Like Beds 3 and 10, it records repeated infaunal reworking of a firm but not fully lithified sea floor.

Bed 15 — Densely Cemented Glauconitic Sandstone (c. 0.3–0.35 m)

Fine-grained glauconitic sandstone, densely calcareously cemented and penetrated by glauconitic sand-filled burrows descending from above. The bed combines strong cementation with clear evidence of downward burrow infill, showing that younger sand was introduced into older firm sediment. It forms another resistant nodular band high in the White Nothe Member.

Bed 16 — Shell-Grit Lag On Hardground (c. 0.05–0.15 m)

A very thin, fine-grained, glauconite-rich weakly calcareous sandstone with comminuted shell grit lying on an irregular hardground. Broken shells and the lag-like texture indicate abrasion and winnowing on the sea floor. This is a classic omission-surface bed and marks another brief episode of shell concentration before thicker sand accumulation resumed.

Bed 17 — Thick Upper Calcareous Glauconitic Sandstone (c. 1.3–1.5 m)

Fine-grained calcareous glauconitic sandstone, only sparsely nodular, but much thicker than most of the beds below and becoming more glauconitic downward. Because it is 1.3–1.5 m thick, it records one of the rare intervals in the member when sediment accumulated more continuously between hardgrounds. Even so, its base and top remain part of the same condensed, omission-rich shallow marine regime.

Bed 18 — Upper Sandy Calcarenites Beneath The Chalk Basement Bed (c. 0.7–0.9 m)

Sandy calcarenites and calcareous sandstone, densely cemented and coarsely nodular, with a network of glauconitic sandstone burrow-fills descending from the bed above. This forms the resistant top of the White Nothe Member immediately beneath the Chalk Basement Bed. It represents the final Upper Greensand deposition at White Nothe before the abrupt change into basal chalk sedimentation and is therefore one of the most important marker beds in the whole locality.

Total Thickness Of White Nothe Member In The Published Composite Section

The published White Nothe composite section totals approximately 7.0–8.8 m, the variation reflecting rapid lateral thickness changes between the western in situ cliffs, the sea cliff below White Nothe and detached landslip blocks. Older memoirs measured about 6.1 m for the former ‘Chert Beds’, but the modern member definition and detailed bed tracing show that the succession is both more complex and more laterally variable than that historical figure implies.

CHALK GROUP

Zig Zag Chalk Formation

Bed WN5 — Chalk Basement Bed (c. 0.5 m)

Immediately above the White Nothe Member lies a c. 0.5 m fine-grained calcareous glauconitic sandstone containing small brown and black phosphatic clasts, hoplitid ammonites, Holaster, Mantelliceras, Schloenbachia and bivalves. Locally it passes laterally into glauconitic sandy chalk, with scour hollows and cobbles of dense calcareous sandstone reworked from the hardground below. This bed marks a major Albian–Cenomanian sedimentary break and is best treated at White Nothe as the local Chalk Basement Bed, the basal glauconitic chalk bed of a strongly diachronous overstep surface, rather than as a simple uniform marl.

Bed WN6 — Condensed Cenomanian Basement Beds And Sandy Basal Zig Zag Chalk

Above the Chalk Basement Bed, White Nothe contains an unusually condensed Cenomanian succession. Older descriptions recognised a thin package of cherty beds, nodular sandstones, nodular limestones and Cenomanian Basement Beds beneath pale chalk, but part of that older terminology straddles the modern Upper Greensand–basal Chalk boundary. The important geological point is that White Nothe preserves an extreme overstep interval rather than a simple thick lower Chalk marl sequence. Derived phosphatised fossils such as Holaster subglobosus, Concinnithyris subundata, Acanthoceras, Calycoceras, Schloenbachia and Scaphites equalis show repeated erosion and reworking around the lower Middle Cenomanian to basal Zig Zag interval.

Bed WN7 — Main Zig Zag Chalk Formation At White Nothe (remaining Cenomanian chalk interval)

The rest of the local Zig Zag Chalk Formation is a pale grey to off-white chalk with a sandy lower part and a distinctly marginal-basin aspect unlike the fuller Grey Chalk sections farther east. White Nothe provides the most westerly coastal exposure of the higher Middle and Upper Cenomanian Zig Zag Chalk before the formation condenses still more strongly farther west. Historical measurements of the whole Cenomanian package at White Nothe range from about 15 m to 24 m, probably because of tectonic disturbance, uneven condensation and the difficulty of measuring sections in landslip terrain. The lower part is notable for porcellaneous, spiky burrow-replacement flints, a rare feature so low in the Chalk of southern England, while the fauna is generally sparse but includes Holaster subglobosus, Concinnithyris subundata, Orbirhynchia wiesti and Terebratulina protostriatula.

Holywell Nodular Chalk Formation

Bed WN8 — Plenus Marls, Melbourn Rock And Meads Marls At The Cenomanian–Turonian Transition

The basal Turonian transition is present at White Nothe but has not been fully logged bed by bed in modern publications. Plenus Marls-type marls, the Melbourn Rock and the Meads Marls are represented, and fossils include a belemnite characteristic of the Plenus Marls and Inoceramus pictus. This interval marks the shift from the marlier Grey Chalk regime into the hard, nodular White Chalk of the Turonian open shelf.

Bed WN9 — Main Holywell Nodular Chalk (c. 23 m)

About 23 m of Holywell Nodular Chalk are present in the White Nothe area. The formation consists of hard, nodular, locally pyritic chalk with thin flaser marls and spectacular shell-debris beds in which Mytiloides fragments can be abundant to almost rock-forming. A flint band at the top of Rowe’s Rhynchonella cuvieri zone probably equates with the Glyndebourne Flints at the base of the New Pit Chalk, making this part of the White Nothe cliff a key Turonian datum section for Dorset.

New Pit Chalk Formation

Bed WN10 — Spurious Chalk Rock And Strongly Reduced New Pit Chalk Interval (c. 1.5 m)

Near the base of Rowe’s Terebratulina lata zone, White Nothe shows a c. 1.5 m band of yellow-green nodules traditionally called the ‘spurious Chalk Rock’. This hardground-rich interval suggests that much or all of the New Pit Chalk is heavily reduced and perhaps largely absent, so that the Lewes Nodular Chalk may rest almost directly on the Holywell Nodular Chalk. Its importance lies not in thickness but in the evidence it provides for a major Turonian erosional or non-depositional event on the Mid-Dorset Swell margin.

Lewes Nodular Chalk Formation

Bed WN11 — Lower Lewes Chalk With Lower Lewes Tubular Flints, Lewes Marl And White Nothe Flint

Below and west of the old coastguard lookout the Lewes Nodular Chalk forms impressive near-vertical faces and is one of the most spectacular parts of the White Nothe section. The chalk is gritty and nodular, with the Lower Lewes Tubular Flints and Lewes Marl clearly developed, while the White Nothe Flint — the type locality for this distinctive horizon — lies between the Lewes Marl and the Navigation Marls. Fossils include abundant echinoids, especially Micraster leskei in and below the Lewes Marl and Micraster normanniae around the Navigation Hardgrounds, together with Chalk Rock brachiopods such as Cretirhynchia minor in the Kingston Nodular Beds equivalents.

Bed WN12 — Upper Lewes Chalk And Light Point Hardground Equivalents

The upper Lewes interval becomes increasingly hardgrounded and locally contains two red, iron-stained, mineralised surfaces developed in erosional channels at about the Light Point Hardgrounds level. Inoceramid shell debris becomes abundant, and toward the top of the formation large Cremnoceramus crassus crassus occurs in association with cross-cutting hardgrounds. This is a textbook example of Coniacian chalk condensation, with repeated pauses in sedimentation and local erosion carved into an otherwise pelagic chalk seabed.

Seaford Chalk Formation

Bed WN13 — Lower Seaford Chalk With Belle Tout Marls And Seven Sisters Flint Band

At the base of the Seaford Chalk, Belle Tout-style marls and the Seven Sisters Flint Band can be recognised at White Nothe, and the basal beds yield abundant thick-shelled inoceramids such as Platyceramus and Volviceramus. In places the inoceramid debris is so abundant that it becomes almost rock-forming. This interval marks the transition from hardground-rich Lewes Chalk into the cleaner, more flinty Seaford Chalk of the middle Coniacian.

Bed WN14 — Upper Seaford Chalk Across The Coniacian–Santonian Boundary

Higher in the Seaford Chalk, large flints near the Coniacian–Santonian boundary include Bedwell’s Columnar Flint Band. Cliffs near the old coastguard lookout yield basal Santonian fossils such as Cladoceramus undulatoplicatus, Gibbithyris ellipsoidalis and Micraster gibbus. Although much of this interval is difficult to examine continuously because of cliff height and landslip, it is an important part of the White Nothe composite succession linking Dorset Santonian chalk with the better-known reference sections farther east.

Newhaven Chalk Formation

Bed WN15 — Marl-Seamed Newhaven Chalk At And East Of Bats Head

At and just east of the White Nothe section, especially around Bats Head, the Newhaven Chalk is readily recognised in the high cliff by closely spaced marl seams weathering out as distinct grooves. The formation is softer and more evenly bedded than the Seaford Chalk below, but still flinty, and regionally is characterised by marl seams and Zoophycos-associated flints. Upper Santonian fossils recorded in the White Nothe succession include Uintacrinus socialis, Marsupites testudinarius, Bourgueticrinus papilliformis and Terebratulina rowei, making this one of the key Dorset sections for the crinoid-rich upper Santonian chalk.

Culver Chalk Formation

Bed WN16 — Lower Campanian Culver Chalk With Offaster pilula And Gonioteuthis quadrata Horizons

Lower Campanian chalk beneath Middle Bottom and farther east includes the lower part of the Culver Chalk Formation. This is a comparatively soft, white, relatively marl-poor chalk with large flints, and it carries classic Dorset records of the Offaster pilula interval; farther east a c. 5 m bed yielded numerous specimens of Actinocamax quadratus in older usage, now referred to Gonioteuthis quadrata. The section here is structurally disturbed and cannot be treated as a simple flat log, but it is biostratigraphically important because Brydone used the White Nothe–Middle Bottom area to recognise subdivisions of the lower Campanian succession.

Portsdown Chalk Formation

Bed WN17 — Highest Chalk Preserved In The Composite White Nothe Section

The highest chalk represented in the White Nothe composite area probably extends up into the Portsdown Chalk Formation, but exposures are discontinuous and accessible mainly by boat, rope or fallen blocks, and no single complete published measured section exists. Regionally the formation is a white chalk with marl seams and flint bands, less uniformly flinty than the underlying Culver Chalk. It is therefore best included here as the highest probable formation in the local composite succession rather than as a confidently logged bed-by-bed cliff section.

Depositional Environment

White Nothe records a long shift from a faulted Jurassic substrate into Albian marine muds and glauconitic sands, then into the most condensed, hardground-rich upper Upper Greensand in Dorset, and finally into open-marine chalk deposition from the Cenomanian to Campanian. The Gault represents relatively quiet offshore mud accumulation during transgression; the Foxmould and White Nothe Member represent shallow marine shelf sand deposition with repeated omission, firmground formation, burrowing, phosphatisation, chert development and local erosion on the Mid-Dorset Swell margin; and the Chalk records progressively more pelagic carbonate sedimentation interrupted by major hardgrounds, flint development and further episodes of condensation.

Structural Style And Stratigraphic Use

White Nothe is one of those classic English coast sections that cannot be understood by reading the cliff as a single neat vertical log. The western part is a broad landslip with rotated blocks below a great wall of Turonian–Coniacian Chalk, while the eastern part around West Bottom and Middle Bottom is tectonically disturbed and locally faulted. The published White Nothe Member log is therefore a composite section, and the higher Chalk succession must be assembled from in situ cliffs, detached blocks, older measured sections and biostratigraphic marker horizons. That complexity is exactly why the locality is so important: it demonstrates Cretaceous overstep, synsedimentary erosion, omission surfaces and basin-margin condensation better than almost anywhere else in Dorset.

Total Thickness Covered Here

The lower Cretaceous part of the locality includes about 12.5 m of Gault, about 30 m of Foxmould and approximately 7–9 m of White Nothe Member in the published modern composite section. Above that lies a strongly condensed Cenomanian package measured historically at about 15–24 m, followed by a much thicker Turonian to Campanian Chalk succession that is demonstrably present but not continuously measurable in one modern face because of landslip, faulting, cliff height and composite exposure. At White Nothe, lithological marker beds and fossil horizons are more reliable than any pretence of a single uninterrupted total thickness.

References

Strahan, A. (1898). The Geology of the Isle of Purbeck and Weymouth.
Arkell, W.J. (1947). Geology of the Country around Weymouth, Swanage, Corfe and Lulworth.
Rowe, A.W. (1901). The Zones of the White Chalk of the English Coast, II: Dorset.
Brydone, R.M. (1914). The Zone of Offaster pilula in the South English Chalk.
Drummond, P.V.O. (1967, unpublished thesis on the Albian–Cenomanian of south Dorset; 1970). The Mid-Dorset Swell: Evidence of Albian–Cenomanian movements in Wessex.
Gallois, R.W. & Owen, H.G. (2017). The stratigraphy of the Upper Greensand Formation (Albian, Cretaceous) of the Isle of Purbeck, Dorset, UK.
Gallois, R.W. & Owen, H.G. (2019). The stratigraphy of the Gault and Upper Greensand Formations (Albian Stage, Cretaceous) of the Dorset and East Devon Coast World Heritage Site, UK.
British Geological Survey Lexicon entries for Gault Formation, Upper Greensand Formation, Zig Zag Chalk Formation, Holywell Nodular Chalk Formation, Lewes Nodular Chalk Formation, Seaford Chalk Formation, Newhaven Chalk Formation, Culver Chalk Formation, Portland Sand Formation, Portland Stone Formation, Purbeck Group and Kimmeridge Clay Formation.
JNCC Geological Conservation Review site account: White Nothe.