Notes on some Chalk sections in N.E. Surrey

2II

NOTES ON SOME CHALK SECTIONS IN SURREY.

N.E.

By A. G. DAVIS.

[Rea" J an. • • nd, 19. 6.J

MANY sect ions were cut in the Chalk in the neighbourhood of Coulsdon, Purley, and Kenley durin g th e year s 1922:I925, when road-making and house-bu ildin g work were in progress. As most of them were temporary , it was desirable th at some record should be made of th e hor izons exposed ; and the following notes have been prepared with that obj ect. In the present communication, however, only sections in or near th e Zone of H olaster planus will be dealt with, since the results of fossilcollecting in the area have modi fied our views of th e distribution of the Reussianum fauna. This fauna, usually regarded as restricted to the sub-zone of Hyphanioceras reussianum, has been found to be well represented in the band at the base of the Zone of Micraster cortestudinarium. Th e discovery of this fauna at an unusual horizon was due t o the search for orga nis ms inside th e shells of Micra sters. A si milar instance of th e preservation of a molluscan fauna inside the she lls of sea-urchi ns has been recorded from th e Chalk of Nor wich (I., p. 401). Syst ematic search for this fauna was m ad e a t the following localities, all of which are included in the area described by Mr. G. W . Young (II., p. 200). Those localities mentioned by Mr. Young are here referred t o by th e numbers that he emplo yed-new exposures are described by reference to th e six-in ch Ordnance Survey Maps (1914 E dition). DESCRIPTION OF SECTIONS. H yphantoceras reussianum, 1. Woodfield Hill. [Surrey, Sheet 19, S.E .] Road widening works ~ - mile south of Coulsdon, South Station. carried out in 1922- 4, by th e Surrey County Council in th e Brighton Road bet ween Woo dfield Hill and Hollyme Oa k Road. A conti nuous section , nearl y a thousand yard s long, with a maximum height of sixteen feet on the west ern side of the road was exposed . The Chalk was sligh tly folded, and dips could be measured of 2° N. at the southern end and 3° S. at the northern end of the cutting. The following beds could be recognized, extending from south to north: ft. ins. Cha lk with layers of nodular flints; a tabular layer at th e base 9 6 S UB-ZONE OF

212

A. G. DAVIS,

Gritty chalk, full of shell fragments with a line of cylindrical flints ft. ins, Micraster, Holaster planus, etc. 3 6 Seam of grey marl Chalk with hard nodules set in a softer matrix (Reussianum Band). Many fossils 5 0 Similar chalk with a line of iron-stained sponges and scattered flints, Micrasters scarce, passing downward into massive jointed chalk without fossils .. .. 13 6 This section gave one of the best exposures of the Reussianum Band, for it was accessible along the whole length of the cutting. During the work of collecting it was found that the Reussianum fauna occurred immediately below the seam of grey marl, which was a conspicuous feature of the section. A line of cylindrical flints was also conspicuous about three feet above the marl seam. The marl seam and the line of cylindrical flints were used as datum lines in the search for the Reussianum Sub-zone at further localities. They proved to be reliable guides and led to the finding of large numbers of Reussianum fossils. The marl seam* in the Planus Zone of this area was noticed by previous writers (Caleb Evans III., p. IS, and Jukes-Browne IV., p. 173), but it was not used for zonal work. The line of cylindrical flints was also recorded by Caleb Evans (III., p. IS), and by Murton Holmes (V., p. 694), who discovered Radiolaria in meal from these flints from Coulsdon. Holmes could not give the exact horizon of the flints as his material came from a spoil heap from the railway (" New Line," Southern Railway) then under construction. Flint meal from the cylindrical flints from Woodfield Hill yielded Radiolaria similar to forms described by Holmes, together with well preserved Foraminifera, etc.

2-'"

2.

Hooley Farm Pit. [G. W. Young. No. 93, Surrey, Sheet 20 S.W.] An overgrown roadside section three hundred yards east of (1) which, when cleared, showed the Reussianum Band overlain by the marl seam. As only two feet of chalk were visible above the marl seam, the peculiar flints were not to be expected. Baculites bohemicus Fritsch, was commoner here than in any of the other sections. 3. Southern Railway Cuttings (" Old and New Lines,") between Woodplace Lane and Star Lane. Collecting was not permissible, but the cuttings can be viewed from the bridges that cross the line and from positions on the Brighton Road. • The marl seam contained only a few Micrastcrs,:which in all cases were slickensided, and washed residues only contained a few ostracods.

NOTES ON SO:\lE CHALK S ECTiONS I N N.E . SU RRE Y.

213

a. The cutting at Woo d p I a c e Lan e forms the downw ard continuation of the Woodfield Hill section (1). It is well weathered and partially overgrown, bu t two marl seams weather out into open seams and can be easily t raced throughout the cuttings. These two marl -seams belong t o th e Zone of T erebratulina lata, in whi ch up t o forty-five feet of chalk are exp osed below the Woodfield Hill Cutting. b. S tar B rid g e. (South of a.) The marl seam in the Plan us Zone is shown here with , lower down, the upp er marl- seam of th e Terebratulina Zone. Th e Chalk a bove thi s cutting was well exposed in 1 9 2 2 when th e Brighton Road at this point was widened. c. F or g e B rid g e. The Planus Zone marl -seam can be traced for some dist ance south of Star Bridge, but when Forge Bridge is reached, vegetation prevents any accurate observation of it. Large spoil heaps still remain between band c, and, from these dumps, Holmes (VI., pp . 45-6) collected and recorded a suite of specimens. Man y of these are pr eserved in th e collections of the Croydon Natural History and Scientific Society and undoub tedly came from the Reussianum Band.

4. Hill Top Pit, Merstham. (G. W. Young. No. 165.] An old pit at the cres t of the escarpment (720 O.D.) almost overgrown, except at the nort hern end, where the following section was visible : ft. in. 3 0 Rubble and chalk Marl seam 0 6 14 6 H ard nodular chalk A few Reussianum fossils were obtained below the marl seam. Mr. T. H. Withers , some years ago, collect ed S caphites geinitzi, d 'Orb., and Solariella gemmata (Sby.), from here. 5.

Kenley. "Tea Gardens." (G. E . Dibl ey (VII., p. 82). G. W. Young , No. 33.J Reussianum fossils have been recorded from here by Dibley. The section is now obscured, but pieces of chalk lying beneath a hedge yielded a few fossils, corroborating Dibl ey 's records. 6. Kenley Station Pit. [G. W. Young. No. 34. Dibl ey VIII., p. 35.J A marl seam two inches thick rises from the floor of the quarry, opposite the entrance, with an inclination of 3° N. and shows about five feet of the Reussianum Sub-zone below it, at the southern extremity of the qu arry. PROC. GEOL. Assoc., VOL. XXXVII., P ART

2,

1926.

14

21

4

A. G. DAVIS,

A specimen of Scaphites was found six inches a bove th e marl seam. Th e cylindrical flint s are in th eir usual position and contain R adiol ari a. Kenley. Southern Railway Cuttings, Oxted Branch. Adjace nt to the R ose and Crown quarry and abo ut one hundred ya rds from the northern end of the Viaduct. Th e first record of the Reussianum Sub-zone in Surrey was mad e hu e by Dibl ey (IX., p . 374). bu t th ere is no clear section. Thi s portion of the cutting was not complete d when E vans (III., p. 16) studi d it.

7.

8. At about 300 yards N.W. of the Viaduct the cuttings are in a fair condition and the beds can be made out on the north side. This part has been described by Evans (III., p. IS) who mentions the presence of marly bands and makes a particular note of the cylindrical flints. In 1925, the Planus Zone marlseam could be seen from the lane which crosses the railway at this point. The beds dip rather strongly t o the north (a measurement could not be taken), and the Reussianum Subzone comes near to the surface at the bridge. Here examples of the cylindrical flints, together with a Micraster, indicative of the horizon, were collected. Dewey and Bromehead (X., p. 10), identified the horizon in this part of the cutting, but gave no records of fossils. Rose and Crown Quarry. [G. W. Young, No. II3. JukesBrow ne IV., p . 173.] A detailed section measured by Hill is qu ot ed by J ukesBro wne, the marl-seams being not ed. The upper seam is about thi rty feet from the top of th e section, and is inacce ssible. R eussianus« fossils have been found after heavy falls of chalk.

9.

10.

Whyteleafe Quarry. [G. W. Young. No. II9.] Shows a similar section to 9 ; but considerably weathered, as the qu arry is now disused. Th e Planus Zon e marl-s eam is accessible with a ladder at the eastern end and, from the chal k immediately below it, a good series of Reussianum fossils were collected . The peculiar flints were not observed in these la st two sections, the high, stee p faces to the quarries preventing an accurate observation. Chatwin and Withers in a footnote to Dibley (IX., p. 374), record Martesia, etc., from fallen chalk here, but were unable to locate the Reussianum Sub-z one. Holmes (VI., p. 46) records Pr ionocyclus neptuni and Nautilus sp . from here. It has already been mentioned that the Plan us Zone marlseam has been used as a guide in locating the R eussian um Sub-

NOTES ON SOME CHALK SECTIONS IN N.E. SURREY.

215

zoie in the district under consideration, an area of approximately sixteen square miles. The marl-seam is apparently not persistent east of the area; there is no trace of it at Keston [Dibley, VII., p. 81). Evidently there is a change between Whyteleafe and Kesten. The chalk above the Reussianum Band at Keston is massive and weathers out, forming a marked terrace (see also Dewey, XI., p. 27). No such chalk (nor is such a terrace to be seen) has been observed in the Coulsdon-Kenley district. A terrace has been noted by Young (I., p. 205) at Chipstead, but the flanks of the Chipstead Valley show very faint indications of terraces; such mere lines as are observable might possibly be the weathered out marl-seams of the Planus and Terebratulina Zones. FOSSILS FROM THE SUB-ZONE OF Hyphantoceras reussianum, A large fauna of upwards of one hundred species was gathered in the preceding sections. Hyphantoceras reussianunt (d'Orb.) is represented by a single broken specimen from Woodfield Hill, and this is the first record of the species in Surrey. The following list is selected, being mainly species unrecorded from this area : Prionocyclus neptuni (Gein.), Aptychus sp., Nautilus sublcevigatus d'Orb., Avellana sp. d. humbolti Muller, Aporrhais sp., Crepidula sp. d. Cooksoniee Seeley., C. sp. d. gaultina Buv., Lampusia ? sp., Solariella gemmata var. a., Woods., Trochus schluteri, Woods., Astarte d. plauensis Gein., Area sp., Carditasp., Cardium sp., Inoceramus costellatus Woods., Nucula sp., Pecten (lEquipecten) pexatus Woods., Pseudoptera d. ccerulescens (Nils.), :::>eptifer lineatus, Sow., Herpetopora anglica, Lang., Arcoscaipellum. angustatum (Gein.) Cretiscalpellum glabrum (Roem.) Many of the small forms were found in the interiors of Micrasters. An undescribed Ammonite was obtained from the Rose and Crown Quarry and has been deposited in the British Museum (Nat. Hist.). ZONE OF Micraster cortesiudinarium, Fairdene Road. Farthing or Fairdene Downs, Coulsdon. [Surrey, Sheet 20, S.W.] 100 yards N.W. of " Reservoir," and! mile N.E. of Woodfield Hill Section (I). During the extension and laying out of this road in 1922-24, a shallow cutting was made to accommodate the new road. Near the "Reservoir" a rubbly, hard, yellowish crystalline chalk was exposed varying in thickness from one to two feet. This bed changed into whiter, but still very hard chalk. Fossils were abundant and included many casts of sponges, N autiius ,

11.

N.E.

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NOTES ON SOME CH A L K SE CTI ON S I N N.E. SURREY.

217

Scaphites, and Pleurotomaria . The Micrasters, usually casts indicating the Zone of Micra ster cortestudinarium, were fairl y abundant and when bro ken up invariably cont ained casts of small gas teropods and other memb ers of the R eussianum fauna. Th is appears to be the first record of the fauna at this horizon. The generalized sect ion from north to south is as follows : White Chalk with lines of flint s both tabular and nodular, the lowest nodular course conta ining large flints set in soft cha lk with many specimens of Br yozoa and Echin ocorys 30 feet Hard, crystalline band .va ryi ng in colour from yellow to white; many fossils, usually casts .. .. 2 feet White chalk with courses of flint s, fossils r arer, including M icrasier, Bryozoa and Echinocorys A part of this bed may belong t o the Planus Zone 20 feet Considerable excavations were made for a drainage trench in this road, and in Red Down Road below it, and a deeper trench, made in the direction of Hooley House, exposed most of the beds from the t op of the T erebratulina Zone t o th at of the Micraster cortestudin ari um Zone. A carefully plotted section shows that this horizon, with the R eussianum fauna in the M i craster cortestudina rium Zone, is a t least sixty feet above the R eussianum Sub-zone pr oper, and probabl y is eighteen or tw enty feet above the base of the Cortestudi narium Zone (fig. 25 p. 2 16) . All available sections kn own to be in this zone were examined, and this little-kn own fauna was found in th e followin g sections . Numerous Micrasters were collecte d and broken up in th e search for enclosed fossils, wit h th e result that th e faun a was found t o occur sporadically about three feet below and about five feet ab ove the h ard rock band. The fossils are record ed in th e t abular list , pp. zI9 - 20.

12. Messrs. Halls' Lime & Cement Works. Marl Pit Lane, Coulsdon. [G. W. Young No. 95: Jukes-Browne, IV., p. 177·] Micr asters, abundant in the lower part of the main workings a nd in the older workin gs, yield no enclosed fossils. However , tw o sp ecimens were obtained in 1912 from a trial hole sunk in the floor of the quarry near the south face, at a depth of six feet. These, when broken up , contained Dentalium sp , S olariella gemmata (Sow.) and a Cyprin a. These forms, together with the Micrasters, can be matched with Fairdene Road (II) specimen s.

13. Marl Pit Lane, Coulsdon. A deep sewer-trench has been cut in 1925 from near th e last section towardsCoulsdon St reet, traversing the Zones of M icraster eortestudin ari um and coranguinum.

218

A. G. DAVIS,

Near Marl Pit Farm (Surrey, Sheet 20, S.W.) Micrasters were obtained which enclosed traces of this fauna.

14. PurleyJunction. [G. W. Young, No. 30.] The lower part of this section is obscured. Evidence of the fauna was obtained from Micrasters in fallen blocks at the central part of the cutting. The bed itself was not located. 15. Northumberland Avenue. Foxley Hill, Purley, 1 mile south of Purley Junction. [(14) Surrey, Sheet 20, N.W.] A new road and drainage works opened in 1924, showing a similar section as at Fairdene Road (II). Occasional greencoated nodules were noticed in the hard band, which was white in colour throughout. 16.

Greathill Shaw. [G. W. Young, No. 128.] A poor section in the lower part of the Cortestudinarium Zone. Material thrown out by rabbits for some distance north of this section yielded several Micrasters which enclosed fossils.

It will be seen that in this area there are two hard rock bands that might each be identified as Chalk Rock. Both contain fossils of the Reussianum fauna. In the case of the upper band the horizon is easily determined by reference to the Micrasters, but the peculiar fauna is to be found, with rare exceptions, only in the tests of these urchins. Hitherto, only two species of larger gasteropods have been recorded from the base of the Cortestudinarium Zone [Chatwin and Withers, XII., p. 106J, but these are not members of the Reussianum fauna (XIII., p. 23). In Berkshire and Oxfordshire the true Chalk Rock is more conspicuous in its lithology, containing numerous green-coated nodules and grains of glauconite, while the higher rock-band is there definitely recognized as the" Top Rock." In Kent (XIII, p. 24) the upper rock-band has been recognized, but it has yet to be determined whether the Reussianum fauna occurs at the higher level in districts outside the area now described. The writer has been assisted during the field work by Miss M. Herbert and Mr. E. Dedryvere, the former, residing at Coulsdon, was able to keep a constant watch on the excavations and report progress. To them is due much of the information given here. Mr. W. P. Robinson, County Surveyor to the Surrey County Council, and Mr. R. Chart, Surveyor to the Coulsdon Urban District Council, both gave every facility for the examination of the works during construction. Messrs. C. P. Chatwin, T. H. Withers, H. Dewey and A. G. Wrigley have readily assisted with help and information. To all, the writer would acknowledge his greatest thanks.

NO TES ON SOME CHAL K SE CTIONS IN N.E. SURREY.

2I9

LIST OF FOSSILS. Rock Band in th e Base of Zone of M icraster cortestudinarium.

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N aut ilus, sp . Scaphi tes geinitei d 'Orb . P rionocyclus ? . , Aporrhais sp . .. Crepidula sp . . . Dentaliu m cf. turoniense \ Vood s. "sp. . ... L ampusia ? sp. .. Pleurotomar i a (Leptomaria) perspectiva (Mant .) So lariella gemm ata (Sow.) Cerit hium sp . Noiicin a sp . T rochu s sp. Area (B arbatia ) d. geinitzi Reuss " d. galli ennei d 'Orb. Cyp rin a sp . Corbis ? morrisoni Woods. Cu spidaria pulchra (Sow .) Cardium (V eni lieardia) sp. D imyodon nilssoni (H a g.) I nocera mu s ineonstans W oods. labiatus var. lata Sow. lamarki P ark . L i m a ' (Plagiostoma) cretacea \ Vood s " sp. Martesia ? rotunda (Sow .) Nu cula sp . Nu culana sp . Ostrea canaliculatus (Sow .) sem i-plana Sow. " uesicularis L a mk. P ecten (Chlamys) cretosus Defr. Plicatula barroisi Peron . S pond yius lata (Sow .) .. spinosus (Sow ). " T rapeziu m trape zoidale (Rom .) A ncistocrani a parisiensis (Morris) Cran ia egnabergensis Retz . R hyn chonella limbata Schlot. plic atil is Sow. reedensis Eth . .. T erebratula " sem iglobosa Sow. Terebratuli na stri ata Dav. L agynopora cf. L. lagena Lang. S erpula ampullacea Sow. fiuctu ata S. W ood w . .. I

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220

NOTES ON SOME CHALK SECTIONS IN N.E. SURREY.

Serpula granulata Sow. gordialis,var. serpentina Goldf. macropa Sow. " plexus Sow. Spinopora sp. .. Cidaris clavigera Kcenig. spp. (radioles) " Phymosoma radiatum (Sorig.) Echinocorys scutaiu s Leske. Holaster placenta Ag ... Micraster -pracursor Rowe. Asteroidea (marginals) Bourgueiicrinus ellipticus Miller Parasmilia centralis (Mant.) Onchotrochus sp. Axogaster sp. .. Camerospongia sp. Cephalites spp. Coscinopora ijundibulijormis Goldf. " quincuncialis T. Sm. Heterostinia obliqua Benett .. Plocoscy-phia convoluta T. Sm. d. fiexuosa Mant. " labyrinthica Mant. Porosphcera globularis (PhiL) .. " patellijormis Hinde Cliona cretacea Portlock Ventriculites spp. Oxyrhina sp. Fish remains indet

I.

II. III. IV.

V. VI.

VII. VIII.

IX.

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REFERENCES. CHATWIN, C. P. Naturalist, 1922. Report on Papers read before Section C. British Association. YOUNG, G. W. Chalk Area of N.E. Surrey, Proc, Geol. Assoc., xix., 1905. EVANS, C. Sections of Chalk between Croydon andOxted. 1870. Lewes. JUKES-BROWNE, A. J. Cretaceous Rocks of Britain. Mem, Geol . SU'YV., vol. Iii., 1904. HOLMES, W. M. Radiolaria from the Upper Chalk at Coulsdon. Quart. [ourn, Geol. Soc., lvi., 1900. HOLMES, W.M. List of fossils collected (Coulsdon). Proc. Trans. Croydon Nat. Hist. Sc. Soc., 1903-4. DIBLEY, G. E. Chalk of theMedwayValley. Proc, Geol. Assoc., xxix., 1918. - - - - Purlev, etc. Proc, Geol. Assoc., xxxii., 1921. Note on the Chalk Rock in N. Kent. Ceol. Mag., Dec. 5, vol. ix., 1912. DEWEY, H., and BROMEHEAD, C. E. N. Explanation of Sheet 270. Mem. Geol. Suru., 1921. DEWEY, H. In Summary of Progress, 1913. Mem, Geol, Suru., 1914· CHATWIN, C. P., and \VITHERS, T. H. Proc, Geol. Assoc., xxvii .• 1916. Ex. Goring and Streatley. CHATWIN, C. P. In Explanation of Sheet 271. Memi Geolc Suru .• 19 24.