The Eocene Succession at LowerSwanwick Brickyard, Hampshire

by DENNIS CURRY and CHRISTOPHER KING

Received 24 April 1964; taken as read 1 January 1965

CONTENTS

1. 1NTROUUCTION2. TOPOGRAPHY OF THE BRICKYARD3. STRATIGRAPHICAL SEQUENCES IN TilE BRICKYARD4. CORRELATION OF SEQUENCES IN 1948, 1951 AND 1957 HOLES5. AGE OF BEDS SEES6. FAL'SA OF THE 1951 ASD 1957 HOLES7. COMPARISON WITH NEARBY SECTIONS .. '

REFERENCES

page 2929303233333435

ABSTRACT: The paper contains a brief account of the London Clay and associatedbeds exposed in Lower Swanwick brickyard, together with correlations with nearbysections in beds of a similar age.

1. INTRODUCfION

THE SUCCESSION at the extensive brickyard (SU501O) of the Sussex &Dorking United Brick Companies Ltd. (formerly the Bursledon Brick Co.)at Lower Swanwick, Hampshire, has displayed a thickness of some 146feet of Eocene beds, mostly or all of London Clay. Much of the sequence isfossiliferous and the fossils are for the most part very well preserved. Thelatest account of the exposures in this brickyard is by Wrigley (1949), whodescribed the sequence visible between 1927 and 1932, comprising sixty­seven feet only. As Wrigley notes, the brickyard was not worked during the1939-45 war but was reopened in 1947or thereabouts. Since that time fourlarge holes have been excavated in various parts of the yard, each showinga succession of about fifty feet of beds. The successions have been provedto overlap and to comprise the whole of the sequence described byWrigley with, in addition, further sequences beneath to the total of 146feet mentioned earlier.

Members of the Geologists' Association visited the brickyard on 1 July1962, and it is thought appropriate to commemorate that visit by this briefaccount of the beds then seen and their relations to other sections nearby.

2. TOPOGRAPHY OF THE BRICKYARD

The brickyard was originally worked by hand to an approximately flatfloor at about twenty feet 0.0., the excavation proceeding in a south-

29

30 DENNIS CURRY AND CHRISTOPHER KING

easterly direction from the kilns. The sequence described by Wrigley wasprobably in the region of 504098, where a steep, partially overgrown, faceof London Clay still exists, rising from the original floor of the yard.

After the war, a bucket digger was used to dig a large rectangular hole,about thirty-five feet deep, at the foot of the overgrown face just men­tioned. This hole will be referred to as the 1948 hole. In 1951 this hole wasabandoned and another, similar, one was dug to the east of the kilns atabout 503102, the 1951 hole. The 1951 hole in its turn was abandoned forthe 1955 hole, excavated in the hill alongside and above the pre-war face atabout 504097. Finally, in 1957, the hole now being excavated was startedoutside the original yard, at 510100.

3. STRATIGRAPIDCAL SEQUENCES IN THE BRICKYARD

The 1948 and 1955 holes are contiguous and the relative positions of thestrata they exhibit can readily be determined. The sequence is describedbelow in descending order.

(1955 hole, beds approximately horizontal.)

Pale brown sandy and glauconitic clay; at the base lenticles up to afoot thick contain abundant small rounded flint pebbles ... seen toLaminated blue-grey clays, more sandy above, weathering to palebrown. These beds are rich in vegetable matter, especially in alenticle at one point at the base. This lenticle yielded Scirpuslakensis Chandler (1962, 50). Other fossils found are Lingula sp.(fragments of shell) and Ostrea sp. and undetermined gastropods(pyritic moulds). Thickness very variable, but up to twenty feet.Rest in broad hollows in unstratified pale grey micaceous silt,which passes downward into blue-grey clay. Total thickness of thelaminated clay and silt series ...Rhabdopleura pebble bed. A layer of scattered large and well­rounded flints up to nine inches long, set in blue-greyclay; seen atbase of hole(Although Rhabdopleura has not been found recently, the late A. G.Davis on a visit to the pit with one of the present authors (D.C.)stated that this is the bed from which his specimens came.)

ft. in.

10 0

25 0

o 6

3 0

22 0

7. Greyish clay6. Rhabdopleura pebble bed. Layer of rounded flint pebbles, resting

on coarse yellow sand... ... up to5. Dark blue stiff clay, passing down into brownish grey sandy clay.

Rare small flint pebbles at six feet up, small septaria at three feetup. No fossils seen

The next lower beds visible are in an old working face about a hundredyards distant, the intervening ground being more or less grown over.

(Old working face and 1948 hole, beds approximately horizontal.)

ft. in.3 0

EOCENE SUCCESSION AT SWANWICK, HANTS 31

ft. in.4. Layer of large septaria, with rare pockets of large molluscs; Pinna,

Turritella, Ostrea 03. Grey sandy clays with molluscs scattered throughout the lowest

twenty-five feet or so ... ... about 30 02. Barnea bed. Grey fine sand, passing laterally into calcareous sand­

stone; it has yielded several rare species of molluscs includingBarnea cf. levesquei (Watelet) and two specimensof the brachiopodTerebratula hantonensis Muir-Wood... 2-3 0

I. Grey sandy clays with scattered molluscs ... ...seen to 8 0

(The lowest thirty feet of the above section is now (1964) under water.)The above will now be compared with the section in Wrigley (1949,

p. 14). It is difficult to reconcile Wrigley's account of the beds above theRhabdopleura pebble bed with what is now seen. However, below theRhabdopleura pebble bed, Wrigley records:

B. Grey, sandy clay with four lines of septariaLarge septaria, six feet down, have abundant Turritella, Cyprinaand Pholadomya spp.

A. Grey, sandy clay with numerous fossils ...Panopea and Pitaria are common at the top. Above a line oftabular septaria, eight and a half feet down, the clay is crowdedwith very large Pinna, Ostrea, and Ficus smithii (J. de C. Sby.),with a varied molluscanfauna. A rich assemblageof Polyzoawasfound upon the large Ostrea.Bedof black flint pebbles in sandy clay: no fossils seen ...

n. in.13 0

15 0

4 0

A comparison of this part of Wrigley's section with that of the oldworking face and 1948 hole indicates that his bed B should equate with theupper part of bed 5, and that A corresponds to parts of 3, 4 and 5, bed 4presumably being Wrigley's line of tabular septaria. If this comparison iscorrectly made, it follows that Wrigley described a section in whichseptarian nodules and fossils occurred at a higher level than that at whichthey are now to be found in the old working face. In addition, his descrip­tion did not include the lower part of bed 3, or any of 1 or 2.

The accuracy of the comparison is confirmed in two ways: (a) Wrigleyrecords from his bed B, but not from bed A, the following molluscs whichhave not been found by the present writers at Lower Swanwick: Murexsubcristatus d'Orb., and Surculites bifaciatus (J. Sby.); (b) the followingfound more or less commonly in beds 1 and/or 2 are not recorded byWrigley: Ostrea multicostata Desh., Turritella cf. dixon; Desh., Voluto­corbis elevata (J. de C. Sby.) and the worm, Ditrupa plana (J. Sby.).

The 1951 hole lies about 600 yards to the north of the 1955 hole. It isnow filled with water.

(1951 hole, dip not noted accurately, but perhaps 2° in a southerlydirection.)

32 DENNIS CURRY AND CHRISTOPHER KING

ft. in.Brown clays, decalcified ... up to 15 0Grey fine sand, passing locally into calcareous sandstone. No fossilsseen. This is believed to be the Barnea bed ... 2-3 0Grey sandy clay with scattered molluscs II 0Shell band, concreted locally into septaria. Turritella cf. dixoniabundant 0 6Grey sandy clay with scattered molluscs, Turritella, Bonellitia,Pollia, Tibia, turrids, Dentalium. Venericor planicosta and Voluto-corbis elevata not uncommon. Thin seams of clayey sand near thebase 5 0Grey clay with fewfossils. Aporrhais sowerbii (fleming) and Arcticasp. frequent in the lowest beds exposed ...seen to 20 0

The 1957 hole, which is still (1964) in work, is on a hill-side about 1000yards due east of the kilns.

(1957 hole, beds approximately horizontal.)

Brown soil, passing down into clay ...Fine grey sand, with doggers of calcareous sandstoneGrey sandy clayLine of scattered septariaGrey sandy clay with Ditrupa and many molluscs, Dentalium, Tibia,BoneJlitia, Volutocorbis elevata, turrids, many Turritella . Venericorfrequent at baseLine of scattered septaria , with seam of Turritella . ..Grey clay with few molluscs, Pseudoneptunea curta (J. Sby.) com­monLine of scattered septar ia. Pinna and Aporrhais sowerbii commonhereaboutsGrey clay with few molluscs. Arctica and Turritella common attwelve feet down ; Pinna common near base seen to

ft. in.4 02 02 0o 6

12 0o 6

12 0

o 6

29 0

4. CORRELATION OF SEQUENCES IN 1948, 1951AND 1957 HOLES

Venericor occurs at only one horizon in the 1951 hole and is associatedwith Volutocorbis elevata which also occurs only at and just above thishorizon . About ten to twenty feet below the Venericor horizon, Aporrhaissowerbii is common. Elsewhere it is rare. The same sequence is to beobserved in the 1957 hole and it seems that these sequences must beequated. About fifteen feet above the Venericor horizon in the 1951 and1957 holes is a two to three feet bed of grey sand which , though un­fossiliferous, closely resembles the Barnea bed of the 1948 hole . Voluto­corbis elevata, Turritella cf. dixoni and Ditrupa plana have been found in the1948 hole, but only in the lowest levels. It thus seems that the lowest tenfeet or so of the 1948 hole are represented at the top of the fossiliferoussequence in the 1951 hole.

On the basis of the above correlations a generalised succession would be

EOCENE SUCCESSION AT SWANWICK, HANTS 33

as follows. The approximate positions occupied by the sequences in theindividual holes are indicated alongside the description of the succession.

-E {GlaUconitic sandy clay, with pebbles at base ...;; Laminated clays, resting on silts . .. ...;E Rhabdopleura pebble bed .. . .. . ...

Grey sandy clays, characterised by Pecten comeus andStreptolathyrus cymatodis in the upper part aboutBarnea bed. Grey sand and sandstoneGrey sandy clays with abundant Turritella cf. dixoniand characterised by Volutocorbis elevata and Veneri­cor plantcosta . .. aboutGrey clays with few fossils; Aporrhais sowerbii andArctica sp. frequent at ten to twenty feet down. Pinnacommon near base . .. seen to

Total, say,

ft. in.10 025 01 0

50 03 0

16 0

41 0

146 0

5. AGE OF BEDS SEEN

Fauna and lithology indicate that the beds below the Rhabdopleurapebble bed should be assigned to the London Clay. However, Chandler(1962, 51) suggested that the laminated clays are of Lower Bagshot age.Wrigley, on the other hand, included these in the London Clay and placedonly the glauconitic sandy clay (ten feet) in the Lower Bagshot Beds. Thisdifference of interpretation may not be important. There is some evidencethat the beds to which the term Lower Bagshots has been applied in theeastern part of the Hampshire area belong to the same sedimentary se­quence as the London Clay and are no more than a sandy continuation ofit. No attempt will be made here to decide whether the nomenclature ofChandler or of Wrigley is more appropriate as applied to the laminatedsilts. It should be borne in mind, however, that the top ten feet of thesection may in fact be the base of the succeeding Bracklesham Beds.

6. FAUNA OF THE 1951 AND 1957 HOLES

The beds exposed in these holes are wholly below those described byWrigley and therefore it seems worth while to list their fauna, so far as ithas been identified:

Vermes. Ditrupa plana (J. Sby.). Polyzoa. Mucronella angustooecium Gregory,Membranipora buski Gregory. LameUibranchia. Nucula curvata S. V. Wood,Nuculana amygdaloides (J. de C. Sby.), Fossularca tumescens (S. V. Wood), Pinnaaffinis J. Sby., Pecten duplicatus J. de C. Sby., Ostrea multicostata Desh., Anomiascabrosa S. V. Wood, Modiolus cr. simplex (J. de C. Sby.), Venericor planicosta(Lk.), Arctica planata (J. de C. Sby.), Nemocardium nitens (J. Sby.), N. hornesi(Desh.), Pitar sulcatarius (Desh.), Panopea intermedia (J. Sby.), Corbula globosaJ. Sby., Pholadomya margaritacea (J. Sby.), Gastropoda. Architectonica pulchra

PROC. GEOL. ASSOC.• VOL. 76, PART I, 1965 3

34 DENNIS CURRY AND CHRISTOPHER KING

(J . de C. Sby .), Turritella cr. dixoni Desh., T. cr. terebellata Lk., Calyptraea cr.aperta (SoL), Euspira glaucinoides (J . Sby.), Globularia adurni Wrig., Sigaticahantoniensis (Pilk.), Tibia sublucida (Edw .), Aporrhais sowerbii (Fleming), Ficuslondini Wrig., Murex subcoronatus d'Orb., Pollia morrisii (Edw.), Pseudoneptuneacurta (J . Sby.), Streptolathyrus cymatodis (Edw.), Ptychatractus cr. interruptus(Pilk.), Euthriofusus transversarius Wrig. , E. crebrilineus Wrig., Volutocorbiselevata (J . de C. Sby.), Bonellitia /aeviuscula (J. Sby.), B. subevulsa (d'Orb.),Turricula gyrata (Edw.), T. teretrium (Edw.), T. stena (Edw.), Eop/eurotomasimi/lima (Edw.), E. prestwichii (Ed w.), E. flexuosa (Edw.), Drillia tereticosta(Edw.), Bathytoma granata (Edw.). Scaphopoda, Antalis annulata (Newton &Harris) . Cephalopoda. Cimonia imperialis (J. Sby.).

There are present also about fifty species in all of Foraminifera andOstracoda.

7. COMPARISON WITH NEARBY SECTIONS

The most important are (a) in the railway-cuttings between Fareham andBursledon, described by Elwes (1888, 1890), (b) in the excavations for anew dock at Portsmouth, described by Meyer (1871).

(a) Railway-Cuttings, Fareham to BursIedon

Wrigley compared the list of fossils he found at Lower Swanwick withthose recorded from the railway-cuttings by Elwes and observed 'differ­ences between the two faunas which become significant by the proximityof the sections'. He noted the absence in his section of Ostrea multi­costata, Turrite/!a cf. dixoni, Ditrupa, Terebratu/a and Denta/ium . One mayadd , from Elwes's lists, Volutocorbis elevata and Venericor (Carditabrongniarti).

These species, which occurred in beds 3 and 2 of the revised section byWhite (1913) of Elwes's account, have since been proved to occur in thelower part of the succession at Swanwick, which of course Wrigley didnot see.

It is now possible to equate with some confidence beds 4, 3 and 2 of thecuttings with the lower part of the Swanwick sequence; bed 1 of the cut­ting, reported as poorly fossiliferous, presumably representing Wrigley'sbeds A and B. The London Clay of Fareham station, lower stratigraphic­ally than those of the cuttings, has faunal links, as Elwes noted, with theBognor Rock. It appears to be older than anything yet seen at Swanwick.

(b) Portsmouth Dock

No detailed analysis is attempted here but it seems probable thatMeyer's clays with Cyprina, containing Pecten corneus, are about equi­valent to Wrigley's beds A and B; his sands with Lingula are at about thesame horizon as the Barnea bed, and the sands with Dentalium equateapproximately with a bed similarly rich in Denta/ium about fifteen feet

EOCENE SUCCESSION AT SWANWICK, HANTS 35

below the Barnea bed at Swanwick. The clays with Ostrea at Portsmouthmight then equate with the poorly fossiliferous clays at the base of thebrickyard section.

REFERENCES

CHANDLER, M. E. J. 1962. The Lower Tertiary Floras of Southern England. 2: Flora ofthe Pipe-Clay Series of Dorset (Lower Bagshot}, London.

ELWES, J. W. 1888. Sections opened on the New Railway from Fareham to Netley.Pap. Proc. Hampshire Field Club, 2, 31-9.

---. 1890. Additional Notes on Fossils at Fareham and Southampton. Pap.Proc, Hampshire Field Club, 4, 80--3.

MEYER, C. J. A. 1871. On the Lower Tertiary Deposits Recently Exposed at Ports­mouth. Quart. J. geol. Soc. Lond., 27, 74-89.

THOMAS, H. D. & A. G. DAVIS. 1949. The Pterobranch Rhabdopleura in the EnglishEocene. Bull. Brit. Mus. (nat. Hist.v Geol., 1, 1-24, pis. 1-3.

WHITE, H. J. O. 1913. The Geology of the Country near Fareham and Havant. Mem.geol. Surv. U.K.

WRIGLEY, A. G. 1949. The London Clay at Lower Swan wick, Hampshire. In Thomas &Davis, supra, 13-19.

D. CurryEastbury GrangeWatford RoadNorthwoodMiddlesex

C. KingDepartment of Geology and GeographyKingston College of TechnologyKingston upon ThamesSurrey