Langton Herring Fossil Hunting

1860 – Langton Hive oysters described
Damon recorded the striking oyster accumulation. The oysters were initially identified under a different name; later work recognized the elongate form of Praeexogyra hebridica.

1940 – Rodden Hive’s age corrected
After examining in-situ material beneath the oyster beds, Arkell corrected earlier assignments of the underlying fossiliferous clay to younger Jurassic formations.

1948 – Variation within a brachiopod population
Aitken and McKerrow, and Blundell, studied the wide range of shell shapes in Herbury Goniorhynchia boueti. Their results showed why extreme forms should not automatically be separated into different species.

1957 – A second brachiopod marker distinguished
Sylvester-Bradley named the Digona Bed, separating the higher Herbury horizon from the basal Boueti Bed and improving comparisons with Bathonian successions elsewhere.

1968 – Fish ear stones investigated
Stinton and Torrens documented fish otoliths from the fossiliferous Rodden Hive succession, demonstrating the scientific value of very small fossils. This is a historical research result, not permission for bulk sampling.

2011 – Two oyster horizons distinguished
The BGS memoir used nearby borehole records to distinguish lower and upper oyster lumachelles and placed the Langton Hive exposure at the upper level. This refines the simpler correlation in older field accounts.

The Fleet-side succession contains several small, separated fossiliferous exposures rather than one continuous cliff section. The inventory keeps each named point distinct and records a significant modern revision to the oyster-bed correlation.

GREAT OOLITE GROUP

The local bedrock succession is Middle Jurassic, principally Bathonian. The geological inventory is not a walking-access licence: named shore exposures may require specific permission.

Age: Bathonian

Fuller’s Earth Formation

Poorly exposed grey clay beneath the fossiliferous Frome succession occurs near Rodden Hive. The GCR estimates about 15 m, rather than recording a continuously measured open face. White mudstone nodules occur toward the top.

Frome Clay Formation

Clay with fossiliferous intervals succeeds Fuller’s Earth. Modern mapping separates these formations, although older literature used Upper Fuller’s Earth Clay for the Frome beds.

Age: Late Bathonian

Wattonensis Beds — Rodden Hive

About 90 m east of Rodden Hive Point, roughly 1 m of grey clay below the lower oyster beds has yielded well-preserved bivalves, brachiopods, belemnites and microfossils. Correlation with the Wattonensis Beds is widely used, although House noted the absence of Wattonithyris. Do not substitute Watton Cliff’s thicker measured section.

Rodden Hive lower oyster lumachelle

Shell-rich rock dominated by the elongate form of Praeexogyra hebridica totals about 1.2 m in the GCR shore account. Historical names include Elongata Beds. The adjacent Wattonensis clay has yielded Myophorella, Rhynchonelloidella smithi and Rugitela powerstockensis.

Langton Hive oyster beds

The conspicuous oyster-rich exposure below the old coastguard station was described as 5–6 m thick in the GCR. Crucially, the 2011 BGS memoir correlates Langton Hive with the upper Hebridica lumachelle, whereas the GCR calls it basal Elongata Beds. Present this as a correlation revision, not as two separate beds both proven in one cliff.

Two oyster levels in local boreholes

Herbury and Seabarn boreholes establish a lower lumachelle immediately above the Wattonensis Beds and an upper one about 30 m higher. Their 1.1 m and 3.3 m thicknesses are borehole measurements, not dimensions of the shore exposures. This evidence underpins the BGS reinterpretation of Langton Hive.

Upper Frome Clay at Herbury

At the north-west corner of Herbury, approximately 7 m precedes the Forest Marble. About 5 m is grey shale; above it are three micritic limestone courses with fine bioclastic laminae and intervening sandy clay. Separate thicknesses for the three limestone courses are not established.

Forest Marble Formation

The Herbury exposures contain two distinct brachiopod-rich marker beds. They represent separate horizons.

Age: Late Bathonian

Boueti Bed — north-west Herbury

A rubbly, shell-rich limestone, 0.6–0.9 m thick, marks the base. Local brachiopods include Goniorhynchia boueti, Avonothyris langtonensis and Dictyothyris coarctata; encrusting bryozoans and serpulids preserve evidence of life on the shells. Herbury is the type locality of G. boueti.

Intervening Forest Marble beds

Green-brown clay, harder muddy laminae and flaggy ooidal shelly limestone occur above the Boueti Bed. House estimated the Digona Bed approximately 18 m higher, but a complete continuously exposed measured interval is not established here.

Basal Digona hardground

A hardened sea-floor surface bears Isastraea and Thamnasteria corals, later encrusted by oysters and bored by bivalves. It records a pause in deposition and ecological succession. No separate thickness is claimed.

Digona Bed — south-east Herbury

Approximately 1.5 m of pale limestone and marl contains Digonella digona, Avonothyris bradfordensis, Dictyothyris coarctata and Rhynchonelloidella curvivarians. A reported Clydoniceras hollandi specimen was loose below the outcrop; its provenance must remain qualified. The locality is the south-eastern corner, correcting the original south-west wording.

Cornbrash Formation — Gore Cove context

The original guide describes rubbly shelly limestone and large bivalves below the Moonfleet area. This is a separately identified extension whose exact outcrop awaits independent verification. Shipmoor’s numbered Cornbrash beds describe a different section, and the source unit of loose bivalves remains uncertain.

Age: Bathonian in original account; exact local range not independently checked

References

Bgs Dorset Memoir
Dgag Fleet
Fleet Rules
Gcr Fleet