Totland Bay Fossil Hunting

1881 – Keeping and Tawney documented the stratigraphy of the Totland Bay and Headon Hill succession
One of the earliest important scientific milestones for Totland Bay came with the classic work of Keeping and Tawney, who documented the stratigraphy of this late Eocene section. Their work helped establish the importance of the Totland Bay–Headon Hill coast in the geological literature.

1889 – Reid and Strahan recorded plant fossils from the Totland Bay succession
Plant fossils from the Totland Bay and Headon Hill coast were recorded by Reid and Strahan in 1889. This marks one of the earliest major published milestones for the site’s palaeobotany and helped show that the succession preserved important late Eocene vegetation as well as shells and vertebrates.

1963–1964 – Marjorie Chandler described key plant fossils from the Totland Bay succession
Chandler’s work added important plant records from the Totland Bay and Headon Hill coast, including material from the lower Bembridge Limestone. This helped establish the area as one of Britain’s key late Eocene plant-bearing successions.

1974 – Bosma described rodent faunas from the Totland Bay Member
The Totland Bay Member proved to be important for vertebrate palaeontology as well as plants. Bosma described rodent faunas from horizons low in the member and from the grey-green marl beneath the How Ledge Limestone, helping establish Totland Bay as a significant mammal locality.

1974 – Daley and Edwards documented the molluscan assemblages of the Headon Hill succession
Work on the molluscan faunas helped clarify the changing freshwater, brackish and lagoonal environments represented in the Totland Bay and adjacent members. This was an important step in understanding the palaeoecology of the coast.

1977 – Feist-Castel described the charophyte succession through the Totland Bay and Headon Hill beds
Charophytes were described from several horizons through the Headon Hill Formation along this coast, including beds in the Totland Bay Member. This made the area especially important for late Eocene charophyte biostratigraphy.

1980 – Rage and Ford described reptiles from the productive marl below the How Ledge Limestone
The grey-green marl immediately below the How Ledge Limestone became recognised as a highly productive vertebrate horizon. Rage and Ford described reptiles from this level, including lizards and snakes, confirming the importance of Totland Bay for small vertebrate faunas.

1985 – Insole and Daley designated Headon Hill as the type section for the Headon Hill Formation
This was one of the most important modern milestones for the locality. Headon Hill was designated the type section for the Headon Hill Formation, and the Totland Bay Member became one of the formally recognised members within that succession. This gave Totland Bay a direct place in the modern stratigraphic framework of the Isle of Wight.

1993 – Headonophis described from beds just below the How Ledge Limestone
A new genus of snake, Headonophis, was described from lignitic clay immediately below the How Ledge Limestone. This is one of the more important named vertebrate discoveries from the Totland Bay Member succession.

1995 – Hooker and colleagues carried out a major multidisciplinary study of the Bembridge Limestone at Headon Hill
Important work on the Bembridge Limestone integrated plant remains, mammals, invertebrates, palynology, organic geochemistry and stable isotopes. This helped show how valuable the Totland Bay–Headon Hill coast is for reconstructing late Eocene environments and habitats.

Modern understanding – Totland Bay is recognised as one of Britain’s key late Eocene reference localities
Today Totland Bay is important for its plant-bearing beds, freshwater limestones, charophytes, molluscs, turtles, crocodilians including Diplocynodon, fishes, rodents and other mammals from the Totland Bay Member and adjacent beds. Its significance lies in combining rich fossils with one of the best exposed late Eocene successions in Britain.

Section Architecture

This is not a single simple cliff log. The locality is a composite of the western and north-facing cliffs of Headon Hill above Hatherwood Point, the north end of Totland Bay, and the north-eastern slope of Headon Hill where the thin remnant of Bembridge Limestone is exposed. The lower part of the succession is best seen at or below the western cliff face and around the Totland end of Headon Hill, whereas the uppermost Headon Hill Formation and Bembridge Limestone are more discontinuously exposed farther north-east.

Structural And Scope Note

The beds north of Alum Bay Chine dip only gently and lie in a broad shallow synclinal structure, in marked contrast to the steeply dipping Alum Bay succession immediately south-west of the reverse fault at Alum Bay Chine. This page covers the Totland Bay–Headon Hill outcrop up to Hatherwood Point and does not continue into the fuller Colwell Bay type section beyond the bay mouth, except where those named members are necessarily represented within the Headon Hill succession itself. The Barton Clay contact is faulted out at the western end, so the practical basal bedrock unit in this locality is the Becton Sand.

BARTON GROUP

Becton Sand Formation (Upper Eocene)

Bed TB1 — Becton Sand At The Base Of Headon Hill (c. 27 m)

The Becton Sand forms the basal sandy unit of the Totland Bay–Hatherwood Point section. At Headon Hill it is about 27 m thick and crops out above the foreshore north of Alum Bay Chine, where it passes beneath the lower Headon beds. Lithologically it is mainly pale fine-grained sand with silty interbeds and local clayey partings, representing the island expression of the upper sand-dominated Barton Group. The depositional setting was marginal-marine to inner-neritic, probably ranging from beach or upper shoreface to shallow sublittoral conditions. The junction with the older Barton Clay is faulted out in this locality, so the base of the sand cannot be logged here as a normal conformable transition.

SOLENT GROUP

Headon Hill Formation (Upper Eocene: Priabonian)

The Headon Hill Formation is the principal unit exposed between Totland Bay and Hatherwood Point and is the type section for the formation itself and for the Totland Bay, Hatherwood Limestone and Lacey’s Farm Limestone members. The succession records repeated shifts between freshwater lakes, marshes, low-salinity lagoons, estuarine waters, channel sands, palaeosols and calcrete-bearing limestones. Because different parts of the cliff and foreshore expose different members best, the bed-by-bed scheme below is a composite one tied to the published Headon Hill log and to the laterally variable outcrops on Headon Hill.

Totland Bay Member

Bed TB2 — Lower Totland Bay Green Clays, Sands And Basal Freshwater Limestones (lower c. 5.7 m of the resolved Headon Hill log)

The Totland Bay Member begins sharply above the Becton Sand and is composed of green clays, silts and fine sands with several thin freshwater limestones and lignitic partings. In the broader lower part of the member lie the classical lower Headon fossil horizons and their Isle of Wight equivalents, including the Cyrena cycladiformis Bed near the base and levels equivalent to the Mammal, Crocodile and Chara beds of the mainland sections. Six charophyte species have been recorded about 1 m above the base of the member, and a green silty clay with shell fragments about 2.5 m above the base has yielded a micromammal fauna. Freshwater turtles, fishes, the alligator Diplocynodon and early Headonian mammals occur in this lower part. Depositional environment: shallow freshwater to slightly brackish ponds, marshes and muddy channel-margin settings on a low-relief coastal plain, with intermittent emergence and palaeosol development. Mammal correlation: early Headonian stehlini–depereti interval.

Bed TB3 — Middle Totland Bay Limnaean Limestones And Warden Ledge Interval (c. 4.8 m)

This part of the member comprises pale freshwater limestones separated by green clays and pale sands. One of these middle limnaean limestone levels is represented north-eastwards by the Warden Ledge limestone, which crops out between Totland Bay and the Warden Point–Colwell sector and is only thinly represented at Hatherwood Point itself. Freshwater gastropods are characteristic, especially Galba, planorbids and Viviparus. These limestones are the first clear freshwater carbonate marker beds of the Headon Hill succession and record short-lived shallow lake expansions alternating with muddier marsh and sandy marginal-lake or crevasse-channel facies.

Bed TB4 — Upper Totland Bay Clays, Sands, Lignites And Shell-Bed Complex Below The How Ledge Limestone (c. 3.7 m)

The upper clastic package beneath the How Ledge Limestone consists of marls, green and grey clays, fine sands and thin lignitic horizons. It includes the Corbicula pulchra Bed and associated green carbonaceous clays, with a mixed low-salinity molluscan fauna in which Potamomya, Melanopsis, Theodoxus and Corbicula are characteristic; Theodoxus shells may preserve original pigmentation and colour patterns. Plant-bearing horizons in this upper part include the Limnocarpus band, with an exclusively aquatic flora of pondweeds (Limnocarpus), water-lilies (Sabrenia) and water-soldiers (Stratiotes), and in-situ conifer stumps with Glyptostroboxylon wood have been recorded from this tract. These beds represent fluctuating freshwater to brackish lake-margin and marsh deposits, with local stagnant-water organic accumulation and repeated salinity changes before the widespread How Ledge freshwater limestone developed.

Bed TB5 — How Ledge Limestone (c. 2.0–2.6 m)

The How Ledge Limestone is the key marker bed of the Totland Bay Member and forms one of the most prominent cream-coloured bands on Headon Hill. It is traceable for about 3.75 km from south-west Headon Hill through Totland Bay to Colwell Bay, and farther to Hordle Cliff on the mainland, where it becomes more marly. At Headon Hill it is a composite freshwater limestone horizon with two limestone units separated by clays; the micromammal-bearing bed TB33 in the studied south-west Headon section is a green silty clay about 0.35 m thick within this interval. Fossils include abundant pulmonate gastropods such as Lymnaea and Australorbis, other planorbids, occasional land snails, Viviparus, charophytes, ostracods, teleost fish, crocodilians, turtles, amphibians, lizards, snakes and micromammals. The freshwater ostracod and molluscan assemblage indicates a very shallow lake or lake-margin, commonly less than a metre deep and potentially emergent, with rooted water plants and algal mats. This bed is one of the most important lake-margin limestones in the British upper Eocene and belongs high in the Totland Bay Member, within the early Headonian vectensis–nanus interval.

Total Thickness Of The Totland Bay Member In The West Totland–Headon Tract: About 27 Metres, Although The Best-Resolved Hatherwood Composite Log Mainly Subdivides Its Upper Part

Colwell Bay Member

Bed TB6 — Basal Neritina Bed And Omission Surface (c. 3.0 m)

The Totland Bay–Colwell boundary is an interburrowed omission surface penetrated by Thalassinoides, marking a clear shift from mainly freshwater Totland Bay facies into more brackish and marine-influenced Colwell Bay conditions. At Headon Hill the fully marine Brockenhurst Bed is absent, and the basal Colwell succession is represented instead by marginal-marine beds comparable with the Neritina and Roydon interval, including dark brown clayey sand, sandy clay and shelly silt. Cerithiids, oysters and corbiculids dominate these low-diversity faunas. Depositional environment: estuarine to lagoonal transgressive mud and sand laid down in a paralic embayment where salinity increased but normal marine conditions were not fully developed.

Bed TB7 — Venus Bed (c. 4.4 m)

The main body of the Colwell Bay Member at Headon Hill consists of blue-green, grey and brown sandy clays and muddy sands representing the Venus Bed. The bivalve traditionally known as Venus incrassata, now Sinodia suborbicularis, is especially characteristic. Low-diversity assemblages with cerithiids such as Batillaria and Potamides, oysters such as Ostrea velata and corbiculids typify the member; the rarely exposed middle part is rather more marine in aspect, and foraminifera suggest that salinities may at times have approached normal marine values. This bed package represents the major transgressive event in the Headon Hill succession.

Bed TB8 — Upper Colwell Lymnaea Limestone And Batillaria Beds (c. 2.2 m)

The upper part of the member comprises a thin freshwater limestone, above which are greenish fine-grained sands and silty clays with shell seams, equivalent to the Batillaria Bed farther north. This upper interval records short-lived freshening within the general Colwell Bay transgression, followed by return to shallow brackish-water sedimentation. At Headon Hill the member is distinctly less marine than at Whitecliff Bay, and the whole Colwell package is a little over 9 m thick rather than the 30 m developed in the eastern Isle of Wight.

Linstone Chine Member

Bed TB9 — Linstone Chine Channel Sand And Microchoerus Bed (0–2 m At Headon Hill; Up To 4 m At The Type Section)

This localised channel-fill sand body is a fine- to medium-grained sand with plant debris, incised into the Colwell Bay Member. It is best developed at the Totland end of Headon Hill and can thin to nothing toward Hatherwood Point, so it must be treated as a laterally variable channel unit rather than as a persistent sheet bed. Its basal bed is the Microchoerus Bed, a buff clay-rich sand with wood debris and mammal remains, including the primate Microchoerus erinaceus. Depositional environment: marginal-marine to estuarine channel fill, cut into the upper Colwell Bay succession.

Hatherwood Limestone Member

Bed TB10 — Lower Hatherwood Limestone (c. 3.5 m)

The lower Hatherwood Limestone is composed of pale, soft to well-lithified fossiliferous freshwater limestones that are unique to Headon Hill and form a major back-scar on the seaward cliff above Hatherwood Point. Root tubes, hardpans and banded limestones or pedogenic crusts occur within the succession, showing repeated soil-forming overprint. The molluscan assemblages are mainly freshwater, especially Galba and planorbids, but hydrobiid-rich intervals and rare foraminifera indicate that saline influence occasionally penetrated the lake system. The member lies in a paralic setting rather than in a permanently isolated inland lake.

Bed TB11 — Hatherwood Lignite Bed (0.4–0.7 m)

The famous Hatherwood lignite is a discontinuous carbonaceous clay and lignitic shell marl resting in hollows on an irregular internal erosion or solution surface within the limestone, about 2 m above the base of the member and about 8 m above the Chara Bed lower in the section. This is the richest mammal horizon in the Headon Hill Formation, yielding the most extensive Headon Hill fauna from a single bed. Turtles, mammals and rodent remains occur in and around the lignite, including the primates originally referred to Adapis and Microchoerus, several species of Palaeotherium, the creodont Hyaenodon, and the pantolestid Dyspterna hopwoodi. The bed represents localized organic accumulation in hollows on a karstic or exposure-modified limestone surface, followed by renewed flooding and burial. Mammal correlation: Headonian pseudosiderolithicus–thaleri interval, broadly equivalent to MP18.

Bed TB12 — Upper Hatherwood Limestone And Palaeokarst Surface (c. 2.8 m)

The upper Hatherwood beds are pale fossiliferous limestones with irregular internal bedding surfaces, hardpans, root-related hollows and marked evidence of pedogenic alteration. At Hatherwood Point a destructive internal surface descends well below the centre of the member, and lignites fill hollows in its extremely irregular profile. Collapse breccias, pothole-like solution features and other palaeokarst structures have been described from the member as a whole, together with calcrete fabrics indicating alternation of wetter and drier conditions. Brackish-water forms become more common upward, and derived Upper Cretaceous microfossils show that nearby Chalk uplands were already being eroded. This is the classic Headon Hill freshwater limestone in which subaerial exposure, soil formation and renewed lacustrine flooding can be studied in unusual detail.

Total Thickness Of The Hatherwood Limestone Member At Hatherwood Point: About 7–8 Metres In The Best Exposed Cliff, Reaching About 9 Metres In The Type Section

Cliff End Member

Bed TB13 — Cliff End Muds, Shell Layers And Pedogenic Marl (c. 9.0 m)

Above the Hatherwood Limestone lie grey-green and brown muds and marls, shaly in part, with thin shell layers dominated by Potamomya and Viviparus, together with a few thin sands. A hard marl horizon less than 0.5 m thick occurs about halfway up the member at Hatherwood Point; it contains knobbly and cylindrical concretions, has a sharp irregular top, and passes downward into marls with vertical red streaks. These are pedogenic features and show that at least part of the member was exposed subaerially. The member as a whole records nonmarine coastal-plain sedimentation in mudflats, marshes and ponds after the more persistent carbonate-lake phase of the Hatherwood Limestone.

Lacey’s Farm Limestone Member

Bed TB14 — Lower Lacey’s Farm Marls And Concretionary Sandy Interval (c. 3.0 m)

The lower part of the Lacey’s Farm Limestone Member is a succession of pale-green marls passing upward into green sandy marl and sand with calcareous concretions. Mammal remains occur at least in the lower part of this unit, although preservation is generally poorer than in the Hatherwood lignite. Deposition took place in a nonmarine lacustrine to palustrine setting in which muddy carbonate sediment accumulated on a low-energy coastal plain and began to acquire strong pedogenic overprinting. Mammal correlation: still within the Headonian pseudosiderolithicus–thaleri interval.

Bed TB15 — Main Lacey’s Farm Rubbly Arenaceous Limestone (c. 3.7 m)

This upper limestone forms the highest major limestone scar above Hatherwood Point. It consists of hard to soft limestones and calcareous sandstones, often nodular or rubbly, with marked internal surfaces, banded crust-like horizons and a distinct top surface locally overlain by pebbles or limestone concretions. The member provides one of the clearest examples in the whole section of calcrete profile development. Northwards it grades laterally into marl and limestone and ultimately dies out. Depositional environment: shallow nonmarine carbonate accumulation repeatedly interrupted by emergence, soil formation and calcretization.

Fishbourne Member

Bed TB16 — Basal Sandstone, Grey-Green Shaly Muds And Local Leaf Bed (c. 4.7 m)

The Fishbourne Member is represented at Headon Hill by a basal brown sandstone with a thin pale-green marl at its base, overlain by grey-green shaly muds. Thin shell beds may occur, but the member is mainly muddy and relatively unobtrusive in the cliff. Reid and Strahan reported a Leaf Bed from the Fishbourne Member at this locality, although no detailed flora has been described from it. The member records marginal-marine to nonmarine sedimentation, probably in low-energy ponds, channels and mudflat waters on a coastal plain that still lay close to brackish embayments.

Osborne Member

Bed TB17 — Osborne Red-Green Mottled Fluviatile Muds (c. 6.8 m)

The Osborne Member is formed of red and green colour-mottled calcareous clay and silt, generally poorly exposed and commonly vegetation-covered. It is largely unfossiliferous and records a nonmarine fluviatile to floodplain environment with prolonged oxidation, waterlogging and soil mottling. In the Headon Hill composite it forms the highest part of the Headon Hill Formation beneath the thin Bembridge Limestone remnant on the north-eastern slope.

Total Thickness Of The Headon Hill Formation In The Hatherwood Point–Totland Bay Composite Section: About 63 Metres Above The Becton Sand, Although The Formation Reaches Greater Thicknesses Elsewhere In The Western Isle Of Wight

Bembridge Limestone Formation (Upper Eocene)

Bed TB18 — Lower Main Bembridge Limestone Succession (c. 5.0 m)

The Bembridge Limestone at Headon Hill is preserved as a thin remnant, best exposed on the north-eastern slope of the hill. Its lower part consists of many white to pale-brown limestone beds representing shallow nonmarine carbonate accumulation. Hooker and co-workers showed that these limestones yielded a complex freshwater and terrestrial signal: calcite casts of Celtis edwardsii, charophytes, fruits of Stratiotes and Caricoidea, leech cocoons, pellets of wood-feeding termites, land snails together with freshwater molluscs, and a diverse mammal fauna. The oldest fauna from the lower limestone indicates open wooded habitats around a freshwater lake or palustrine complex.

Bed TB19 — Middle Shelly Muds (c. 1.4 m)

Grey, blue or green shelly muds overlie the main limestone package and represent a quieter water, more muddy phase within the Bembridge Limestone succession. These beds still belong to a freshwater to marginal-lacustrine system but record a reduction in carbonate hardness and probably greater persistence of standing water than in the lower limestones. They also form part of the mammal-bearing upper sequence recognized in the Headon Hill multidisciplinary studies.

Bed TB20 — Upper Grey Marls And Brown-Black Shelly And Non-Shelly Muds (c. 1.0 m)

The topmost preserved Bembridge Limestone strata at Headon Hill are grey marls with intercalated brown to black shelly and non-shelly muds. Bosma’s original HH6–HH7 localities and later collecting by Hooker and co-workers showed that these beds contain numerous mammal horizons, including black muds with shell fragments that yielded the rodent Ectropomys exiguus. The higher Bembridge Limestone fauna indicates more closed wooded habitats than the lower limestone fauna and is correlated with the medium–curtum interval, commonly placed near European mammal reference level MP19. Local lignitic palaeochannel muds in the upper part are unique to this locality. No younger Bouldnor Formation is logged in this page, because the Bembridge Limestone is the highest bedrock unit actually exposed within the chosen Totland Bay–Hatherwood Point tract.

Total Thickness Of The Bembridge Limestone Formation At Headon Hill: Up To About 7.5 Metres

Depositional Environment

The Totland Bay–Hatherwood Point succession records the final infilling of a shallow marine basin and its passage into a low-relief paralic landscape of lakes, marshes, channels and calcareous flats during late Eocene time. The Becton Sand represents marginal-marine to shallow sublittoral sand deposition. The Totland Bay Member records freshwater to slightly brackish ponds, marshes and channel sands with several freshwater limestones, culminating in the widespread How Ledge lake-margin limestone. The Colwell Bay Member is the main transgressive interval, with brackish to near-marine estuarine and lagoonal faunas. The Linstone Chine Member records a local channel cut into the Colwell succession. The Hatherwood Limestone is a freshwater limestone complex uniquely developed on Headon Hill, repeatedly exposed, calcretized and locally karstified, with a vertebrate-rich lignite in an internal erosion surface. The Cliff End, Lacey’s Farm, Fishbourne and Osborne members record mainly nonmarine coastal-plain, lacustrine, palustrine and fluviatile deposition with strong pedogenic overprint. The Bembridge Limestone at the top represents renewed freshwater limestone and marl sedimentation in a lake–marsh system bordered by open woodland to denser forest.

Total Thickness Covered Here: Approximately 95–100 Metres Of Upper Eocene Stratigraphy From The Becton Sand Formation Through The Headon Hill Formation To The Top Of The Bembridge Limestone Formation Across The Composite Totland Bay–Headon Hill–Hatherwood Point Section

References

Hopson, P.M. & Farrant, A.R. (2015). Geology of the Isle of Wight, British Geological Survey sheet explanation.
Insole, A.N. & Daley, B. (1985). A revision of the lithostratigraphical classification of the late Eocene and early Oligocene strata of the Hampshire Basin, southern England.
Daley, B. & Balson, P. (1999). British Tertiary Stratigraphy, Geological Conservation Review Series 15, including the Headon Hill and Totland Bay and Headon Hill site accounts.
Cleal, C.J., Thomas, B.A., Batten, D.J. & Collinson, M.E. (2001). Mesozoic and Tertiary Palaeobotany of Great Britain, Geological Conservation Review Series 22, Headon Hill and Totland Bay account.
Hooker, J.J., Collinson, M.E. & Sille, N.P. (1995). Reconstruction of land and freshwater palaeoenvironments near the Eocene–Oligocene boundary using multi-proxy evidence from Headon Hill, Isle of Wight.
Hooker, J.J. (1987, 1992) and Hooker, J.J. et al. (2005) on the Headon Hill mammal succession, Headonian biozones and correlations.
Cray, P.E. (1973). The stratigraphy and mammalian palaeontology of Headon Hill.
Bosma, A.A. (1974). Micromammals and the stratigraphy of Headon Hill.
Murray, J.W. & Wright, C.A. (1974) on the foraminifera of the Headon Hill succession.
Keen, M.C. (1977). Ostracod assemblages and depositional environments of the Headon Hill and Bembridge successions.
Paul, C.R.C. (1989). Freshwater molluscs from the Hatherwood Limestone Member.
Vasileiadou, K., Hooker, J.J. & Collinson, M.E. (2022). Taphonomy of an Eocene micromammal assemblage in the How Ledge Limestone, Headon Hill.
Newell, A.J. & Evans, D.J. (2011). Timing of basin inversion on the Isle of Wight and evidence from the Headon Hill Formation.
Keeping, H. & Tawney, E.B. (1881). Classical early descriptions of the Headon Hill and How Ledge succession.