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PALAEONTOGRAPH ICAL SOCIETY M ONOGRAPHS THE AMMONOIDEA OF THE PLENUS MARLS AND THE MIDDLE CHALK C. W. WRIGHT & W. J. KENNEDY 148 Pages; 32 Plates © THE PALAEONTO GRAPHICAL SOCIETY • LONDON October 1981 The Palaeontographical Society issues an annual volume of serially numbered publications; these may either be a single complete monograph or a part of a continuing monograph. Publication No. 560, issued as part of Volume 134 for 1980 Recommended reference to this publication: W right, C. W. & K ennedy, W. J. 1981. The Ammonoidea of the Plenus Marls and the Middle Chalk. Monogr. Palaeont. Soc. London: 148 pp., 32 pis (Publ. No. 560, part of Vol. 134 for 1980). ABSTRACT The ammonite fauna of the Plenus Marls and Middle Chalk (Upper Cenomanian and Turonian) is described; it comprises 49 spccies and subspccics (8 new), referred to 27 genera. These provide a basis for revision of the ammonite zonation of the Upper Cenomanian and Turonian of Great Britain and correlation with the sequences in the Paris Basin and the stratotype areas in Sarthe and Touraine. It is demonstrated that the Ccnomanian-Turonian boundary is best taken between the Neocardioceras juddii Zone below and the Watinoccras coloradoense Zone above. RliSL'Mli La faune d’Ammonites des Plenus Marls et de Middle Chalk (Cenomanien Superieur et Turonien) est decrite, elle comprend 49 especes et sous-especes (dont 8 nouvelles) rapportees a 27 genres. L’ctudc de cctte faune permet une revision de la zonation basee sur les Ammonites dans lc Cenomanien Superieur et le Turonien de Grande-Bretagne; cllc scrt aussi de support k l’etablissemcnt d’unc correlation avec les successions connues dans le Bassin de Paris et les stratotypes de la Sarthe et dc la Touraine. On demontre qu’il est preferable de placcr la limite Ccnomanien-Turonien entre la Zone a Neocardio- cerus juddii el la Zone a Walinoceras coloradoense sus-jacente. KURZFASSUXG Die Ammonitenfauna der Plenus-Mergel und der Mittleren Kreide (Oberes Ceno- man und Turon) wird beschrieben; sie umfaBt 49 Arten und Unterarten (8 neu), die zu 27 Gattungen gestelll werden. Diese bilden eine Grundlage fur die Revision der Ammoniten-Zonengliederung des Oberen Cenomans und Turons in GroBbritannien sowie fur die Parallclisicrung mit den Schichtenfolgen im Pariser Becken und den Typus- Gcbietcn in Sarthe und der Touraine. Es wird gezeigt, daC die Cenoman/Turon-Grenze am bestcn zwischen der Zone des Neocardioceras juddii untcn und der des Watinoceras colorado ense oben gezogen wird. PE3K)M£ Onncana aMMonmoEaji ijiayna iu ILieuyc ilapaa u Mito-'i Io.ik (sepxmiii cenoMan n TvpoH), BKJlKmKnna.H 49 muon n nn.imiôn (8 uoeijx), onieeeiiHbix k 27 po;;a.M. 3to âeT ochobv jtJUi pcuiinnu auMOHHTOBOll ôniuiijiHjoni ropxn^rn cenoMaiia ii Tvpona Be.îuKoopiiTaHUU ll Koppcnimini e piupcija.Mii IlapnvKUKorci fiaeceiiiia ;i cTpaTOTiinniRCKiix ri.io;na,Ti,cn Copxu ii Tvpeaa. B itanecTEe nauoajiee y,io6jioro ypOEHa eenoMaHCK.o-TypoHCKoii rpannnLi npeuiaraeic;! aouajiwiwli py5cm Neocardioceras juddii/Watinoceras coloradoense.. Aiade and printed in Great Britain Adlard & Son Ltd., Bartholomew Press, Dorking THE AMMONOIDEA OF THE PLENUS MARLS AND THE MIDDLE CHALK CONTENTS Page Introduction. . . . . . . . . . . . . . 3 Stratigraphical introduction . . . . . . . . . . . 3 Ammonite occurrencc and preservation . . . . . . . . . 9 Locality details . . . . . . . . . . . . . 10 Conventions and techniques . . . . . . . . . . . 15 Acknowledgements . . . . . . . . . . . . 16 Systematic descriptions . . . . . . . . . . . . 16 Order Ammonoidea . . . . . . . . . . . . 16 Suborder Ammonitina . . . . . . . . . . . 16 Superfamily Desmocerataceae Zittel . . . . . . . . 16 Family Desmoceratidae Zittel . . . . . . . . . 16 Subfamily Puzosiinae Spath . . . . . . . . 16 Puzosia Bayle . . . . . . . . . . 17 Puzosia (Puzosia) Bayle . . . . . . . . . 17 Puzosia (Anapuzosia) Matsumoto . . . . . . . 19 Parapuzosia Nowak . . . . . . . . . 20 Parapuzosia (Austiniceras) Spath . . . . . . . 20 Family Pachydiscidae Spath . . . . . . . . . 29 Leivesiceras Spath . . . . . . . . . . 29 Superfamily Acanthocerataceae de Grossouvre. . . . . . . 32 Family Acanthoceratidae de Grossouvre . . . . . . . 32 Subfamily Mantelliceratinae Hyatt . . . . . . . 33 Calycoceras Hyatt . . . . . . . . . . 33 Pseudocalycoceras Thomel . . . . . . . . . 36 Tarrantoceras Stephenson . . . . . . . . 38 Tarrantoceras (Sumitomoceras) Matsumoto . . . . . . 38 Thomelites Wright & Kennedy . . . . . . . 39 Neocardioceras Spath . . . . . . . . . 49 Watinoceras Warren . . . . . . . . . 51 Subfamily Euomphaloceratinae Cooper . . . . . . 54 Euomphaloceras Spath . . . . . . . . . 54 Kamerunoceras Reyment . . . . . . . . . 56 Romaniceras Spath . . . . . . . . . . 58 Romaniceras (Tubariceras) Matsumoto, Saito & Fukada . . . 60 Subfamily Mammitinae Hyatt . . . . . . . . 62 Metoicoceras Hyatt . . . . . . . . . . 62 Spathites Kummel & Decker . . . . . . . . 73 Spathites (Jeanrogericeras) Wiedmann . . . . . . . 74 Mammites Laube & Bruder . . . . . . . . 75 Pseudaspidoceras Hyatt . . . . . . . . . 8 1 Metasigaloceras Hyatt . . . . . . . . . 83 Family Vascoceratidae H. Douville . . . . . . . . 84 Subfamily Vascoceratinae H. Douville . . . . . . . 85 Nigericeras Schneegans . . . . . . . . . 85 Vascoceras Choffat . . . . . . . . . . 86 1 2 THE AMMONOIDEA OF THE PLENUS MARLS &c Fagesia Pervinquiere . . . . 87 Subfamily Pseudotissotiinae Hyatt . . . . 98 Thomasites Pervinquiere . . . . . . 98 Family Collignoniceratidae Wright & Wright . . . . 101 Subfamily Collignoniceratinae . . . . . . 101 Collignoniceras Breistroffer . . . . . . 102 Lecointriceras Kennedy, Wright & Hancock . . . 108 Subprionocyclus Shimizu . . . . . . 109 Suborder Ancyloceratina Wiedmann . . . . . 110 Superfamily Turrilitaceae Gill . . . 110 Family Hamitidae Gill . . . 110 Hamites Parkinson . . . 110 Family Anisoceratidae Hyatt . . 110 Allocrioceras Spath . . . . 110 Family Baculitidae Gill . . . . 112 Sciponoceras Hyatt . . , . . . 112 Family Turrilitidae Meek . . . . . . 116 Subfamily Nostoceratinae Hyatt . . . . 116 Didymoceras Hyatt . . . . . . 116 Superfamily Scaphitaceae Gill . . . . 116 Family Scaphitidae Gill . . . . . . 116 Subfamily Scaphitinae Gill . . . . . 116 Scaphiles Parkinson . . . 118 Incertae sedis . . . . . . . . . 1 1 8 Stratigrapliic results and conclusions . . . . . 1 1 8 Appendix . . . . . . . . 127 References . . . . . . . . 128 Index . . . . . . . 140 STRATIGRAPHICAL INTRODUCTION 3 INTRODUCTION The present monograph is the first of an intended series describing the Upper Cretaceous ammonite faunas that were within die scope of Daniel Sharpe’s Description of the fossil remains of Mollusca found in the Chalk of England (1853-7). Sharpe provided competent descriptions and beautifully clear and only occasionally misleading illustrations of a wide range of Chalk ammonites which, with d’Orbigny’s classic volume on the Cretaceous ammonites of France, again beautifully but more misleadingly illustrated, served as the main foundation for later knowledge of the taxonomy and biostratigraphy of Upper Cretaceous ammonites, on which many authors have built. Under the policy, decided at the Palaeontographical Society’s Centenary, of increasing the usefulness of the earlier monographs, Wright & Weight (1951) published a synoptic supplement to Sharpe’s monograph, “primarily a nomenclatorial revision” of that work. They sought to integrate all taxonomic attributions and new records published since Sharpe’s day, particularly the important contributions by L. F. Spath, together with unpublished work, but this filled the gap only for a few years. A vast corpus of published work from all over the world, new ideas on taxonomy and massive new collections have made monographic revision not only possible but essential. The present monograph has been undertaken first because of the importance of the pioneer English species and the more or less accurately dated English faunal succession to the continuing work of the International Geologic Correlation Programme project “Mid Cretaceous Events”. The urgency of publishing the much larger Lower Chalk faunas is mitigated by Kennedy’s (1971) paper ‘Cenomanian Ammonites from Southern England’. The scope of the present monograph is, in accordance with the Society’s recent practice as regards works on Cretaceous ammonites, based on the English formations and not on international stages. It covers with the Middle Chalk the latest Cenomanian Plenus Marls fauna, the latter commonly excluded from the Lower Chalk. It excludes the Upper Turonian Chalk Rock fauna, from the base of the Upper Chalk, which has recently been described by Wright (1979). STRATIGRAPHICAL INTRODUCTION Subdivision of the Chalk At the turn of the eighteenth century, when William Smith began to record the sequence of rocks in the neighbourhood of Batii, he divided the Chalk into two parts only, a lower part without flints and an upper part in which flints were present. A decadc later Townsend (1813), describing the chalk in Wiltshire around his parish in the Vale of Pewsey, recognized three divisions: “1. Immediately on the sea coast at Chichester, as above mentioned, and along the most elevated parts of Hants and Wilts, particularly at Tidworth, to the South of Everly, it is milk-white, fine in its grain and smooth when cut, writes readily on wood, and is fit for the cooper, for whiting, for lime, and for manure. It is Creta Scriptoria of Linnaeus. 2. In descending the hills from Everly to the vale of Pewsey, a second bed appears, hard, rubbly, and tinctured with green, improper for the uses to which the former is applied, and fit only for the highways. 3. Under this we find what is, with us, called a malmy chalk,* unctuous to the touch, of a grey or greenish white, unfit for any of the fore-mentioned purposes. The separation between each of these beds and the succeeding is not abrupt, but gradual: for, commonly, when contiguous strata, apparently formed by subsidence, occur, they mix and run into each other. Agreeably to this observation we find, under these beds, a rubbly bed of chalk with silicious sand, united by a calcareous cement. *Marga Gretacea, Lin." His middle division is readily identifiable with the Chalk Rock, whilst the lowest probably includes what is now regarded as the Lower Chalk. Five years later Mantell and Phillips gave more precise divisions of the Chalk. Mantell (1818) 4 THE AMMONOIDEA OF THE PLENUS MARLS &c divided the chalk into ‘Blue Mari’, ‘Chalk Mari’, ‘Lower or Hard Chalk’ and ‘Upper or Flinty Chalk’. What is essentially the same subdivision is repeated in his better-known ‘Fossils of the South Downs' (1822). His ‘Blue Marl’ corresponds to what is now known as Gault, his ‘Lower Chalk’ corresponds to parts of what is now known as the Lower and Middle Chalk. This usage is im portant to note, as many of the Middle Chalk ammonites in old collections are labelled ‘Lower Chalk’. Phillips’ divisions, although presented in a paper read to the Geological Socicty in 1818, were not published until 1821; he rccognized six divisions of the chalk near Dover (Kent) classified in four groups. For nearly 50 years after this most workers on the English Chalk adopted a three-fold division into Chalk Marl, Lower Chalk without flints and Upper Chalk with flints. Other divisions were used by Woodward (1833), who divided the Norfolk Chalk into ‘Upper Chalk with many flints’, ‘Medial Chalk with few flints’, ‘Lower Chalk without flints’ and ‘Chalk Mari’. Sharpe (1853), in the Introduction to his Monograph divided the Chalk into: “1. Upper Chalk; my specimens of which are principally from Norfolk, or from Gravesend and Northfleet: this division is rich in Organic Remains. 2. Middle Chalk, which contains but few fossils: those examined are mostly from Kent, Sussex and the Isle of Wight. 3. Lower or Grey Chalk, containing numerous fossils, especially Ammonites and Turrilites: the neighbourhood or Dover, and of Lewes, and the Isle of Wight furnish large supplies; many specimens have also been procured from numerous chalk pits along the foot of the North Downs, and others have been obligingly sent from Devizes . . . 4. The “Chloritic Marl” of the Isle of Wight, a bed some six or eight feet thick at the base of the Chalk, is very rich in Organic Remains . . . The “Chalk with Siliceous Grains” of Somersetshire, is probably on the same parallel as the “Chloritic Marl” and also contains an abundance of shells . . .” Some idea of the range of his Formations is given by the ammonites recorded from them; his Upper Chalk records include forms now referred to the genera Parapuzosia, Lewesiceras, Pachydiscus and Menuites-, Middle Chalk: Lewesiceras and Collignoniceras; Lower Chalk: Acantkoceras, Protacan- thoceras, Mantelliceras, Calycoceras, Euomphaloceras, Romaniceras, Metasigaloceras, Sharpeiceras, Paracaly- coceras, Hyphoplites, Schloenbachia, Forbesiceras, Scaphites, Hypoturrilites, TurriliUs, Marietta and Ostling- oceras. The earliest satisfactory division into zones is that of Evans (1870), who recognized the follow ing divisions of the Chalk around Croydon and Oxted: “ 1. Zone with Micraster coranguinum = Purley Beds. 2. Zone with Micraster coranguinum = Upper Kenley Beds. 3. Zone with Micraster corbovis and Holaster Planus = Lower Kenley Beds. 4. Zone with Inoccramus Brongniarti and Galerites subrotundus = Whiteleaf Beds. 5. Zone of Ammonites pcrarnplus and Inoceramus mytiloides= Upper Marden Park Beds. 6. Zone of Ammonites varians and Belemnitella plena = Lower Marden Park Beds.” In France during this same period a rather more sophisticated division of the Chalk (and of the Cretaceous generally) evolved. During the early part of the nineteenth century a lithological division into craie blanche, craie tuffeau and craie chloritee was used (e.g. Brongniart 1822, d’Archiac 1839) until d’Orbigny (1843) divided the Chalk into stages, at first recognizing only two, the Senonian and Turonian; he subsequently (1847) confined the name Turonian to the upper part of that stage as originally conceived and named the lower part Cenomanian. The earliest attempt at correlation of the stages of d’Orbigny with the divisions of English geology was that of Barrois (e.g. 1876) who showed that the whole of the Upper Cretaceous in England could be divided into the same zones as he recognized in France: f Zone a Belemnitelles „ . J Zone a Marsupites enonian 2one ^ Micraster coranguinum (_Zone k Micraster cortestudinarium STRATIGRAPHICAL INTRODUCTION 5 f Zone a Holaster planus Turonian ■< Zone a Terebratulina gracilis l^Zone a Inoceramus labiatus "Zone a Belemnites plenus Zone a Holaster subglobosus Cenomanian -< Chloritic marl Zone a Pecten Asper Zone a Ammonites inflatus Subsequently, amongst others, Jukes-Browne (1887) and Jukes-Browne & Hill (1887) extended Barrois’ observations; in 1896 they provided a detailed correlation of the Lower Chalk and the arenaceous Cenomanian in south-west England already studied by Meyer (1874). At the beginning of this century (1900-1904) Jukes-Browne & Hill’s great work the ‘Cretaceous Rocks of Britain’ was published. This still provides the best overall account of the English Upper Cretaceous. In this work the Belemnite Marl was regarded as a unit at the top of the Lower Chalk and referred to the Holaster subglobosus Zone. After a full review of the work of previous decades, the Middle Chalk was regarded as consisting of two zones, Rhynckomlla cuvieri below and Terebratulina, previously Terebratulina gracilis, above. The base of the formation was marked by the Melboum Rock, a hard nodular sequence first named by Jukes-Browne in 1880. The upper limit of the Middle Chalk was defined as a line “at the base of the Chalk Rock or of the beds which correspond with it.” This usage was followed and applied with great precision by Rowe in a series of papers (1900- 1908) in which almost all the coastal sections in England and a large number of inland exposures were fully described. The same scheme is in general use today, with Orbirhynchia as the correct genus for R. cuvieri, Inoceramus (or Mytiloides) labiatus as an alternative index for the lower zone and Terebratulina lata as the correct name for Terebratulina gracilis. The zonation is easy to apply in the field and, with the general rarity of ammonites in the Middle Chalk, has not been replaced by an ammonite zonation comparable with that now coming to be accepted for the Lower Chalk. The detailed inoceramid sequence outlined by Kauffman (1978) offers promise of a generally applicable finer system of zones. If the divisions and limits of the Middle Chalk have remained stable for three quarters of a century, the same cannot be said of the Belemnite Marl (Jukes-Browne & Hill 1886), Plenus Marls (White 1909) or Actinocamax plenus Zone (Jukes-Browne & Hill 1903). This has been variously assigned to the Lower and to the Middle Chalk and attached as a subzone to the subglobosus and to the cuvieri or labiatus zones. Since the time of Barrois (1876) it has been known to occur through the Anglo-Parisian Basin. Jefferies (1962, 1963) has shown that it can be divided throughout this region into eight units (Text-fig. 1). The Melbourn Rock is recognized as a complex of incipient hardgrounds, nodular chalks, conglomerates and true hardgrounds which has gradational contacts below and above. It varies widely in thickness and its limits are diachronous. Above this horizon no named lithostratigraphic units are in widespread use in the Middle Chalk except for the “Spurious Chalk Rock” (Rowe 1908), a horizon of yellow and green-coated nodules near the top of the T. lata Zone in parts of southern England. However stratigraphic position may often be recognizable from the detailed accounts by Rowe. The facies in Devon is rather different from that elsewhere in England. The lower levels are highly condensed and contain abundant ammonites. The division of the Devon Cenomanian by Jukes-Browne & Hill (1903) into Beds A, B and C in ascending order is in general use. Smith (1961) renamed Bed C the “Orbirhynchia Band” (after O. wiesti) because he thought that “Bed C of the Cenomanian Limestone” was an inappropriate name as it was Turonian. It is in fact Cenomanian and there is no good reason to change the well established nomenclature. At several points on the Devon coast Bed C is overlain by a nodular, pebbly unit called the 6 THE AMMONOIDEA OF THE PLENUS MARLS &c MIDDLE CHALK: INOCERAMUS LABIATUS ZONE. Melboum Rock, a hard, nodular chalk with rhythmically bedded incipient hardgrounds. Calcarenitic, with abundant Inoceramus debris. Local floods of Sciponoceras boheinicum anterius at the base indicate the Neocardioceras juddii Zone, PLENUS MARLS. Divided into 8 Beds. A rhythmic alternation of more and less argillaceous chalks, with important erosion surfaces (ES) as marked. Oyster casts of Metoicoceras geslinianum Zone ammonites in bed 1 at Steyning, Sussex and ammonites from Bed 2b upwards, with Calycoceras naviculare, Austiniceras austeni and Scapkites cf» equalis in Bed 2-3 and Euomphaloceras septemseriatum and Pseudocalycoceras dentonense in beds 5 and 7-8 respectively. Actinocamax plenus is restricted to beds 4-6. The erosion surface at the boundary of Beds 3-4 corresponds to the Rotalipora cushmanij Praeglobotruncana stephani Zone (below) and Praegiobotruncarw. spp. Zone (above) boundary. The base of the Plenus Marls is an erosion surface of regional extent, but it grades up into the succeeding Middle Chalk. Top of LOWER CHALK. Argillaceous chalk with Inoceramus and thin-shelled J/okistfer the commonest fossils. Ammonites and other iiragonitic fossils generally rare, but the top 10 m have yielded C. (C.) naviculare, Eucalycoceras pentagonum, Protacanthoceras bunburianum and Tkomelites at localities such as Eastbourne (Sussex) and White Nothe (Dorset). Text-fig. 1. The standard sequence in the Plenus Marls of south-east England* based on the exposures at Merstham. Surrey, showing the divisions mentioned in the text and some of the more important ammonite occurrences (after Jefferies 1962, 1963). Neocardioceras Pebble Bed, a term first used by Smith & Drummond (1962). Above this the lithology differs in detail from that of the Middle Chalk of the rest of southern England but the standard zones of cuvieri (or labiatus) and lata are in current use. The formational terms Lower, Middle and Upper Chalk have throughout the study of the English Chalk been combined with a system of zones based on assemblages of fossils of various STRATIGRAPHICAL INTRODUCTION 7 phyla. Stage names gradually came into use from the beginning of the present century but a system of stage names and ammonite zones never displaced the traditional system, although the significance of the occurrence in the Middle Chalk of large ammonites (mainly Lewesiceras peram- plum (Mantell) below and rare Collignoniceras woollgari (Mantell) above) had long been recognized. Ammonite zonation In the 1920s, however, Spath proposed various sets of zones for the Plenus Marls and Middle Chalk. In 1923 (p. 144) he divided the Cenomanian as follows: Upper Cenomanian } Metoicoceras pontieri (Acanthoceratan) Acanthoceras cenomanense [subglobosus-zone of authors] Calycoceras bay lei Lower Cenomanian Euomphaloceras euomphalum (Schloenbachian) > Hyphoplites falcatiis J \varians-zone of authors] Mantelliceras martimpreyi The Metoicoceras pontieri zone was the equivalent of the Plenus Marls. Three years later (1926, p. 425) the following scheme appeared as part of a table of Ceno manian zones: Sub-Voiles Old £ones Turonian (Mammitan) whitei plenus pontieri vicinale subglobosus Upper Cenomanian subfiexuosum rhotomagense upper varians (Acan tho c eratan) diadema (= euomphalus) vectense In the same year (1926a, table facing p. 80) the following appeared in a table of the subdivisions of the White Chalk: Approximate Ammonite horizons zonal equivalent ^ Pseudojaco b ites farmeryi Hoi. planus (Chalk Rock) Hyphantoceras reussianum Prionocyclus neptuni Angoumian Prionotropidan ■< Coilopoceras requinianum [sic] Romaniceras deverianum Romaniceras ornalissimum T. lata Prionotropis carolinus Vascoceras sp. Mammites nodosoides Pseudaspidoceras footeanum Rh. cuvieri Ligerian Mammitan Fagesia superstes Metoicoceras whitei Rhotomagian Metoicoceras pontieri A. plena As with Spath’s division of the Cenomanian (reviewed by Kennedy 1969, 1971), this is a combination of intuition and guesswork and bears little relationship to any faunal successions demonstrable in the field. Several of the ammonites listed as successive are in fact contemporaries and several do not occur in England. Spath’s divisions, although occasionally mentioned in passing or included in tables in text-books, never came into general use. 8 THE AMMONOIDEA OF THE PLENUS MARLS &c Thirty years later Wright (1957, p. LI 28) gave the following as “standard” zones for the Turonian of the “Classic Areas of Western Europe” (descending order): Subprionocyclus neptuni Collignoniceras woollgari Mammites nodosoides Metoicoceras whitei Subsequently Wright (1960) gave the Devon sequence as follows (descending order): Bed with Watinoceras Bed with Neocardioceras Bed with Plesiovascoceras catinum, Metoicoceras gourdoni, M. geslinianum, Kanabiceras septemseriatum. Hancock (in Basse 1960) equated the two lower horizons with the Plenus Marls. In 1962 and 1963 Jefferies published a full description of the English Plenus Marls. He divided the beds into two ammonite zones of Metoicoceras geslinianum below and M. gourdoni above. Wright and Jefferies both followed Spath in referring the Plenus Marls to the Turonian. In 1973 Kennedy & Juignet and Juignet, Kennedy & Wright pointed out that Metoicoceras geslinianum and M. gourdoni occurred in the type Cenomanian and that, contrary to the views of Tablr 1. Zones and lithological divisions of the Plenus Marls, Middle Chalk and their corielatives AMMONITE TRADITIONAL LITHOSTRATIGRAPHIC UNITS TRADITIONAL STAGE ZONE ZONE DEVON ELSEWHERE FORMATIONS Holaster UPPER CHALK Chalk Rock UPPER CHALK Subprionocyclus planus (part of) (in some area6) (part of) neptuni u in r L n n Terebratulina Collignoniceras tale woollgari TURONIAN MIDDLE MIDDLE CHALK CHALK Orbirhynchia cuvieri Mammites or Melbourn nodosoides Inoceramus Rock labiatus Watinoceras coloradoense Neocardioceras Neocardioceras juddii Pebble bed Metoicoceras Aclinocamax Plenus marls PLENUS MARLS geslinianum plenus CENOMANIAN Beds A - B LOWER CHALK and remanit Grey chalk (part of) faunas