Fossils of Barton-on-Sea by Gordon Stone

Location: Barton-on-Sea is located on the South Coast of England, in the county of Hampshire, the nearest large town being Bournemouth. It is easily accessible using either the A337 through the New Forest or the A35 from Bournemouth.

The main fossiliferous location is between Highcliffe and Barton-on-Sea itself and is best accessed from either the car park for Highcliffe castle or the car park at Barton.

Background: Barton-on-Sea is the type-site for the Bartonian formation of the upper Eocene period and covers the period from about 44 to 37 mya. It was a marine environment, believed to be similar to that in southeast Asia today. In later stages it became more estuarine as the sea silted up leaving marshes and lagoons.

The Barton formation is divided into a number of beds, lettered from A to K. These are grouped into three phases, Lower, Middle and Upper which are much more useful in the field, as the individual beds are not easily distinguished. Lower Barton consists of beds A1, A2, A3 and B and is mainly glauconitic clays. Middle Barton consists of beds C, D, E and F and is mainly sandy clays. Upper Barton consists of G, H, I, J and K and is more sandy. It was during the Upper Barton stage that the environment became more estuarine.

Today the Barton formation consists of a slumped cliff face with 2 or 3 low, flat, plateaux. These are often heavily waterlogged and collecting on this area between October and March is not recommended. These slumped cliffs extend onto the foreshore and in places are being continually washed away giving fresh exposures. The Eocene strata are unconformably capped by Pleistocene gravel.

Fauna: The fauna at Barton-on-Sea is quite prolific, if somewhat limited in its scope, consisting mainly of bivalves and gastropods, although vertebrate remains in the form of sharks teeth are not uncommon. Over 600 species of mollusc have been collected from this formation and in a weekend a keen collector should be able to find at least 100 without undue difficulty. Most of the Barton fauna, although abundant, is quite small (below one inch) but a few gastropod species grow up to about 6 inches. A breakdown of the major faunal groups and their status, including some of the most common species found follows:

Foraminifera: 2 species of the genera Nummulites were previously fairly common in lower Barton beds but the relevant strata are now mostly covered by sea defences.

Anthozoa: 1 genus of small coral, Turbinolia, is regular throughout the marine strata, but at less than 1 inch in size needs searching for.

Bryozoa: 2 small bryozoans have been recorded, but I have never personally found any.

Annelida: The tubes from 3 species of worms are common in middle Barton strata, the largest at up to 3 inches being Protula extensa.

Mollusca: These are by far the most common elements of the fauna, there being at least 400 gastropod and 225 bivalve species, not to mention 4 scathopod species. A list of the 10 most common species, in alphabetical order follows:

Athleta lucator [Gastropod]
Bathytoma turbida [Gastropod]
Cardiocardita sulcata [Bivalve]
Denatlium bartonense [Scathopod]
Crassatella sulcata [Bivalve]
Glycymerita deleta [Bivalve]
Rimella rimosa [Gastropod]
Sycostoma pyrus [Gastropod]
Turricula rostrata [Gastropod]
Turritella imbricataria [Gastropod]

Echinodermata: These form a very minor part of the fauna with only the radioles from 'Cidaris' websteriana being anything other than rare.

Crustacea: These are again a minor part of the fauna with 3 main groups being recorded. Ostracods are the most common with about 20 species. Next are Decapods [crabs and allies] with parts, mainly claws, from 10 or so species and finally Cirripedes [Barnacles] with 1 species, Balanus unguiformis. Chondrichthyes: About 30 species of sharks and rays occur with teeth being the most common fossil although vertebrae are not unknown. The most common species found are:

Jaekelotodus trigonalis [Shark teeth]
Myliobatis striatus [Ray dental plate]
Striatolamia macrota [Shark teeth]

Osteichthyes: The most common bony fish remains are vertebrae and otoliths, of which over 100 different types have been recorded.

Reptilia: Except for portions of turtle carapace all other reptile remains are very rare at Barton, crocodile scutes and snake vertebrae being the only other recorded fossils.

Mammalia: Very rare. 2 genera of whale, Prozeuglodon and Basilosaurus, have been recorded.

Plantae: Lignite up to the size of large branches is quite common, showing that land was never far away, while recognisable cones, fruits or seeds are very rare.

Collecting: Collecting at Barton-on-Sea is very much seasonal, with the spring being by far the best time. Collecting in the winter period, October to March, is not normally effective as the only accessible strata is along the foreshore at low tide, the cliffs being too muddy and dangerous. In summer only exceptionally high tides reach the cliff face and the cliffs are largely overgrown with vegetation giving limited scope for collecting. Spring, March to June, is the optimum collecting period. The seas regularly wash the cliff face exposing new material, the tides are low enough to make sieving on the beach worthwhile and the cliffs are dry enough for safe access.

Spring collecting at Barton-on-Sea is simplicity itself, the only necessary tools being a trowel, a penknife or similar sharp digging instrument and plenty of collecting bags. The majority of fossils are lying on the surface having washed down from higher levels, while those that are in situ are normally easily excavated from the dry matrix using a penknife. Any collector with a specific interest in sharks teeth should be amply rewarded by sieving the gravel exposed on the beach at low tide.

Selected Bibliography: There are no books available giving a breakdown of all the fossil species found at Barton-on-Sea but the following give a good background to both the geology and the more common species:

British Caenozoic fossils published by HMSO, London. ISBN 0 11 310024 8.

British Regional Geology, The Hampshire Basin published by HMSO, London. ISBN 0 11 884203 X.

Illustrated Guide to Barton Fossils by John Cooper.

There are also occasional articles in the bulletins issued by the Geological Association, the Palaeontological Society and the Tertiary Research Group in England.