Lee-on-the-Solent Fossil Hunting

1862 – Osmond Fisher described the Bracklesham strata at Lee-on-Solent
One of the earliest important scientific milestones at Lee-on-Solent was the work of Osmond Fisher, who described the Bracklesham beds here in 1862. His observations helped establish the site as an important Hampshire Eocene locality and provided the framework for later fossil work.

1976–1977 – Elasmodus kempi described from Lee-on-Solent
Lee-on-Solent produced the type specimen of Elasmodus kempi, one of the site’s most important named fossil discoveries. This chimaeroid helped confirm the exceptional importance of Lee for Middle Eocene fish faunas, especially cartilaginous fishes.

1979 – six species of fossil birds described from Lee-on-Solent material
The bird fossils from Lee-on-Solent were described by Harrison and Walker in 1979. These included six species, making the locality one of the very few British sites to yield a significant Middle Eocene avifauna and one of the most important bird localities of this age in Europe.

Late 1970s – vertebrate-bearing beds at Lee-on-Solent were documented in detail
Work in the late 1970s showed that several beds at Lee-on-Solent contained vertebrate remains, including sharks, rays, chimaeroids, bony fish, reptiles, birds and mammals. This established the site as one of the richest Middle Eocene vertebrate localities in southern England.

1980 – Lee-on-Solent recognised as an important mammal locality
By 1980, fossil mammals had also been recorded from Lee-on-Solent, including remains referred to Propalaeotherium, Palaeotherium and Lophiodon. Although much rarer than the fish material, these finds added further importance to the site.

1980s – Lee-on-Solent established as one of Britain’s richest Middle Eocene shark localities
Later work confirmed that Lee-on-Solent had yielded more than 30 species of shark, together with several chimaeroids and a rich otolith fauna. This made the site one of the key British localities for Middle Eocene marine vertebrates.

Modern understanding – Lee-on-Solent remains a key Bracklesham Group vertebrate site
Modern reviews continue to recognise Lee-on-Solent as an important Bracklesham Group locality for shark teeth, fish remains, otoliths, birds and other vertebrates. Even though parts of the historic exposure have been affected by sea-defence work, the site remains significant in the study of British Middle Eocene vertebrates.

Section Architecture

Lee-on-the-Solent is not a single continuous cliff log. The Selsey Sand Formation is best logged on the lower foreshore between Knight’s Bank, Monk’s Hill and the eastern seafront, whereas the Elmore Member is exposed farther south-east at Elmore; the actual Selsey–Elmore junction is hidden beneath a Pleistocene channel-fill, and modern sand, shingle, algae and engineering works commonly mask large parts of the outcrop.

BRACKLESHAM GROUP

Selsey Sand Formation

Selsey Sand Formation Note

The published labels L1–L11iii are Kemp’s Lee-on-the-Solent bed numbers and are retained here exactly. Older literature called these beds the upper Selsey Formation or Selsey Division; in current BGS usage they belong to the Selsey Sand Formation. The Lee Selsey section is a glauconitic, fully marine, strongly bioturbated shallow-shelf succession and is especially important for shark, ray and teleost remains, with rare middle Eocene bird bones recorded from several levels.

Bed L1–L3v — Campanile Bed Package (c. 4.59 m; lowest part partly augered)

L1–L3v comprise the basal Campanile Bed package of the Lee section, although the classic fossiliferous Campanile horizon is not cleanly exposed in the main foreshore and the lowest bed L1 was proved only by auger; the basal part is exposed separately at Croften Cliff to the west. Grey glauconitic sand, laminated silty clay and bioturbated silty sand dominate, with abundant molluscs near the base and increasingly sandy, burrowed facies through L3i–L3iv. The package records shallow fully marine sedimentation on a glauconitic inner shelf, with alternating quieter mud settling and more active burrow-reworked sand deposition.

Bed L3vi — Silt Bed (0.99 m)

Dark green-grey silty glauconitic sand with intense bioturbation at the upper contact and rare black pebbles throughout. Invertebrates, vertebrate debris and plant remains are all recorded from this bed, making it one of the lower fossil-yielding horizons in the Selsey succession at Lee. It represents a current-worked marine silt-sand floor with repeated burrowing and periodic terrestrial organic input.

Bed L4 — Shell-Bearing Glauconitic Sand (0.50 m)

Green to dark green clayey, silty glauconitic sand with many bivalves and burrows infilled with glauconite. This is a shelly, heavily bioturbated marine sand bed formed during a short interval of greater sand input and benthic activity than in the finer beds above and below.

Bed L5i–L5ii — Amusium corneum Bed (2.24 m)

Grey-green to blue-grey sandy clay with fine glauconite, becoming more sandy and glauconitic upward, with thin burrows filled by fine pyritic sand and occasional concretions. Molluscs and vertebrate remains are frequent, especially in L5i, and this interval lies within the main bird-bearing middle part of the Selsey section at Lee. The bed records quiet shallow-marine clay deposition interrupted by burrowing, pyritization and local concentration of shell and vertebrate debris.

Bed L6i–L6iii — Miocardia Bed (1.68 m)

Grey-blue to brown-grey silty to clayey glauconitic sands, with large calcareous concretions in L6i, some containing bored driftwood near the upper contact, and with rare bivalves, small gastropods and occasional Nummulites. This named bed represents shell-bearing shallow-marine sands with early concretion growth, woody drift input and a moderate benthic fauna on a glauconitic sea floor.

Bed L7i — Lower Pinna Bed Sand And Pebbly Base (0.57 m)

Dark green-grey glauconitic sandy clay to silty sand, intensely bioturbated at the base, with occasional rounded black pebbles and large molluscs above. This bed marks the incoming of the Pinna Bed facies and records a shell-bearing, mobile shallow-marine substrate.

Bed L7ii — Main Pinna Bed (1.80 m)

Grey-brown stiff sandy clay, slightly slickensided at the top, with fine glauconite and large flat oval concretions in the upper part, many surrounding colonies of Pinna and concentrated Nummulites variolarius. Small molluscs are common throughout, and rare vertebrates occur in green-sand pockets. This is one of the classic Lee shell-and-vertebrate beds and represents a colonized marine bottom with local shell concentration and patchy early cementation.

Bed L7iii–L8 — Upper Pinna Bed Clays (2.79 m)

Grey-green stiff sandy silty clays with well-preserved bivalves, passing up into grey stiff clays with brown patches. These upper Pinna Bed muds represent quieter marine conditions than L7ii, with continued benthic life but less obvious sand concentration and more uniform muddy sedimentation.

Bed L9 — Lower Brook Bed (0.76 m)

Green-grey sandy clay to silty sand with fine glauconite, thin burrows filled with pyritic sand and a more sandy middle part. A diverse invertebrate fauna and vertebrate remains are recorded from this bed, which is one of the more productive fossil horizons on the Selsey foreshore. It represents a burrowed shallow-marine silt-sand bed with repeated pyrite formation and shell/vertebrate accumulation.

Bed L10 — Upper Brook Bed (1.06 m)

Grey-green stiff slickensided clay in which molluscs and Nummulites are concentrated in small sandy lenses. Compared with L9, this bed is muddier and more condensed in appearance, suggesting quieter background sedimentation interrupted by localized shell and larger-foraminiferal concentrations.

Bed L11i–L11ii — Lower Nummulites variolarius Bed (0.55 m)

Green-grey sandy clay overlain by a very thin grey stiff clay, with abundant Nummulites and large molluscs. This is the lower part of the topmost nummulitic Selsey package and records a strongly shelly, larger-foraminiferal shallow-marine bottom.

Bed L11iii — Upper Nummulites variolarius Bed (0.51 m)

Grey glauconitic sandy clay weathering yellow-brown and packed with Nummulites variolarius, molluscs and lignitized driftwood. This is the distinctive top of the Selsey Sand Formation at Lee, comparable with the classic Variolarius Bed of the Isle of Wight, and it is best interpreted as a very shallow warm-marine shell-and-nummulite facies, probably associated with seagrass-rich conditions immediately below the Barton transgression.

Total Thickness Of The Logged Upper Selsey Sand Formation At Lee-on-the-Solent: Approximately 18.0 Metres, Although The Lowest Part Is Partly Augered And The Top Contact With The Elmore Member Is Concealed

BARTON GROUP

Barton Clay Formation

Elmore Member

Elmore Member Note

The numbered units 1–11 are the published Elmore succession of Kemp and co-workers and are retained exactly. Only the lower 9.05 m of the member is exposed at Elmore, and most beds are heavily decalcified; apart from the Coral Bed, fossils are usually preserved as pyritic moulds, phosphatic nodules or microfossil residues of diatoms and agglutinating foraminiferids. Regionally the Selsey–Barton boundary is an omission surface, but at Lee the actual junction is concealed by Pleistocene deposits.

Bed 1 — Basal Glauconitic Sandy Clayey Silt (0.98 m)

Mid-green glauconitic sandy clayey silt forming the basal exposed Elmore facies. Although the actual basal surface is hidden, this unit represents the incoming of fine muddy Barton facies above the nummulitic top-Selsey beds and records low-energy marine deposition with dispersed glauconite and abundant microfaunal and vertebrate debris.

Bed 2 — Pale Blue Stiff Clay, Increasingly Sandy Downward (1.54 m)

Pale blue stiff clay becoming sandier and more glauconitic downward, with slickensiding in the lower part. This is a quiet-water mud unit with strong compaction fabrics and is one of the more argillaceous, diatom-rich levels in the Elmore section.

Bed 3 — Green Silty Glauconitic Sand With Clay-Filled Burrows (0.32 m)

A thin green silty glauconitic sand penetrated by clay-filled burrows. This bed marks a brief renewal of sandier input and active bioturbation on an otherwise muddy sea floor.

Bed 4 — Mid-Green Finely Glauconitic Sandy Clay (0.60 m)

Finely glauconitic sandy clay with some medium-grained quartz and glauconite. The coarser admixture suggests slightly more energetic sediment influx than in the surrounding units, but the bed remains a marine mud-rich facies rather than a true sand body.

Bed 5 — Thick Lower Elmore Clay (2.15 m)

Pale blue-green stiff slightly sandy clay, slickensided at upper and lower contacts and glauconitic in the lower part. This is the thickest lower unnamed Elmore clay and another microfossil-rich argillaceous unit, representing prolonged low-energy muddy marine sedimentation before the incoming of the Coral Bed.

Bed 6 — Coral Bed (0.90 m)

Pale blue-green shelly sandy clay with interspersed siltstones. This is the only Elmore bed at Lee to retain obvious calcareous macrofossils in place and yields solitary corals including Paracyathus caryophyllus, bivalves such as Amusium corneum, Chlamys cf. trigintaradiata, Pitar sp. and Nucula sp., together with large serpulids such as Protula cf. extensa. It is the key marker horizon of the lower Elmore Member at Lee and records a shelly marine bottom with firmer substrate and a brief interval of better carbonate preservation.

Bed 7 — Rimella canalis Bed, Basal Nodular Unit (0.42 m)

Pale blue-green sandy clay with nodular claystones and siltstones throughout. This bed is probably the source of some of the Elmore vertebrate fauna, and phosphatic nodules at or close to this level yield rare pyritized casts of Ectinochilus planum – the gastropod historically used to define the Rimella canalis Bed – together with crustaceans and other vertebrate remains. It marks the base of the published Rimella canalis Bed package.

Bed 8 — Rimella canalis Bed, Lower Pyritic Clay (0.80 m)

Pale blue stiff pyritic clay, slickensided at the upper contact. This is a reduced, low-energy muddy sublayer within the Rimella canalis Bed package and one of the more argillaceous diatom-rich levels in the Elmore succession.

Bed 9 — Rimella canalis Bed, Laminated Middle Unit (0.35 m)

Pale blue-green laminated clay with very fine glauconitic sand and tabular siltstones at the upper contact. Fine lamination indicates quiet settling punctuated by thin silt influxes, and rare pyritized Nummulites have been noted here even though larger foraminifera are otherwise largely confined to the underlying top-Selsey bed and higher Barton boundary levels.

Bed 10 — Rimella canalis Bed, Upper Pyritic Clay (0.46 m)

Pale blue stiff pyritic clay. Macrofaunal evidence is sparse and the unit represents another quiet-water reducing clay phase within the upper part of the Rimella canalis Bed package.

Bed 11 — Rimella canalis Bed, Top Sandy Clay With Burrows And Lignite (0.52 m)

Pale blue-green pyritic glauconitic sandy clay with clay-filled burrows and mollusc-bored lignite. Crushed moulds of bivalves, scaphopods, naticids and the distinctive strombid Ectinochilus planum characterize the published Rimella canalis Bed at Lee, and the lignite and bored woody fragments show repeated organic input to the sea floor. This is the highest exposed Elmore bed at the locality, but the member continues upward regionally beyond the visible foreshore.

Total Thickness Of The Exposed Elmore Member At Elmore: 9.05 Metres, Representing Only The Lower Part Of A Regionally Thicker Member

Pleistocene And Recent Cover

At Elmore, a Pleistocene channel-fill masks the junction between the Nummulites variolarius Bed of the Selsey Sand Formation and the basal Elmore Member. Elsewhere along the shore the Eocene beds are blanketed or intermittently hidden by Pleistocene and Recent sands, gravels, shingle and mud, and modern coastal engineering has further reduced the continuity of exposure.

Exposure And Collecting Note

Lee-on-the-Solent is best treated as a foreshore collecting and correlation locality rather than a measured cliff section. Classical exposures were modified or locally buried by sea-defence and engineering works, especially in the late twentieth century, so productive ground is now patchier and strongly dependent on tide, storm cleaning and temporary stripping of beach cover.

Depositional Environment

The Lee-on-the-Solent middle Eocene succession is wholly marine. The upper Selsey Sand Formation records a glauconitic shallow-shelf to very shallow inner-marine system with bioturbated sands, shelly clays, drifting wood, local Pinna colonies, diverse mollusc beds and a topmost nummulitic facies comparable with a warm shallow seagrass-rich setting. The overlying Elmore Member records renewed muddy marine transgression above a regional omission surface, with decalcified glauconitic clays and silts, diatom- and agglutinated-foraminifera-rich microfacies, a discrete coral-shell horizon, phosphatic crustacean and vertebrate nodules, and a higher pyritic Rimella canalis Bed package.

Total Thickness Covered Here: Approximately 18 Metres Of Upper Selsey Sand Formation And 9.05 Metres Of Lower Elmore Member Are Documented At Lee-on-the-Solent, But They Are Exposed In Separate Low-Foreshore Sections Rather Than As A Single Continuous Face

References

Fisher, O. (1862). On the Bracklesham Beds of the Isle of Wight Basin.
Kemp, D.J., King, A.D., King, C. & Quayle, W.J. (1979). Stratigraphy and biota of the Elmore Formation (Huntingbridge division, Bracklesham Group) at Lee-on-the-Solent, Gosport, Hampshire.
Kemp, D.J. (1985). The Selsey Division (Bracklesham Group) at Lee-on-the-Solent, Gosport, (Hants).
Curry, D., King, A.D., King, C. & Stinton, F.C. (1977). The Bracklesham Beds (Eocene) of Bracklesham Bay and Selsey, Sussex.
Edwards, R.A. & Freshney, E.C. (1987). Lithostratigraphical classification of the Hampshire Basin Palaeogene deposits (Reading Formation to Headon Formation).
British Geological Survey Lexicon of Named Rock Units: Bracklesham Group, Selsey Sand Formation and Barton Clay Formation.
Dineley, D. & Metcalf, S.J. (1999). Fossil Fishes of Great Britain, Geological Conservation Review account for Lee-on-Solent.
Benton, M.J., Cook, E. & Hooker, J.J. (2005). Mesozoic and Tertiary Fossil Mammals and Birds of Great Britain, Geological Conservation Review account for Lee-on-the-Solent.
Kemp, D.J. (1999). Recent coastal protection and associated temporary exposures to the Middle Eocene coastal sections at Lee-on-the-Solent, Gosport, Hampshire.
Barnet, J. (2023). Geological evolution of the Hampshire Basin during a global climate transition from hothouse to coolhouse in the Palaeogene.