PROPOSED LECTURE AT THE BRITISH GEOLOGICAL SURVEY
NOTTINGHAM. MARCH 16th 1991 at 2pm
The stratigraphy of the Ferriby, Welton, Burnham and Flamborough Formations.
[by Felix Whitham]
Firstly may I introduce myself as an unknown geriatric, serious amateur fossil collector, with a great love of geology, particularly chalk stratigraphy, who senses he is about to be recorded on one of his own stratigraphical sequences, as a species extinction horizon.
Over the past 40 years or so I have worked the Yorkshire Wolds pits, and the coastal region collecting fossils from the chalk, logging exposures, and recording horizons of some of the main macrofaunas. Since retiring 7 years ago I have been able to complete this work with the help of members of the Hull Geological Society, particularly Mike Home and Lynden Emery who have given much assistance in measuring some of the more difficult bits where access in some instances has been precarious.
Two papers have been submitted to the editor of the Y.G.S. Proceedings. The first is confined to the Stratigraphy of the Ferriby, Welton, and Burnham Formations, which is made up of 10 exposures located North of the Humber and fills in some of the gaps in the composite section north and south of the Humber established by Wood & Smith(1978), (the key Willerby section was not fully exposed at that time). This later succession provides a firm framework for the first detailed account of all the main macrofaunas. More precise fossil ranges are established, enabling clearer definition of biozones, and an informal subdivision of the H. rostrata Z. introduced. (Succession = 215 metres.)
The second paper provides the first detailed account of the succession of the Flamborough Formation mainly along the coast plus several inland sections (Succession = 215 m). I am now faced with the difficult task of presenting a stratigraphic succession of over 400 metres in about 30 minutes. Time permits only a brief description of the faunas and stratigraphy.
Chalk north of the Humber accumulated on the northern part of the East Midlands shelf and adjacent southern margin of the Cleveland Basin. The basinal sequence is limited to the north eastern corner of the Wolds, where Albian to Turonian chalks are considerably thicker than on the shelf. The white chalk shelf facies are fairly uniform over north and south Humberside. It thickens towards the coast.
HUNSTANTON FORMATION (Red Chalk)
The basal Hunstantion Formation Red Chalk is of Middle and Upper Albian age. Wood & Smith (1978) included this in the Ferriby Formation. Here the author follows Jeans, Kent and Rawson (same paper) in regarding it as a separate formation. The base of the Ferriby Formation is thus taken from the top of the bored upper surface of the Red Chalk (Hunstanton Formation).
The Red Chalk sequence is very fossiliferous, mainly terebratulids and belemnites. Rare ammonites include Leymeriella sp., Dimorphoplites hilli, Anahoplites sp. and Mortoniceras (M) sp.. Among the inoceramids present are Birostrina concentricus and B. sulcatus, and Inoceramus anglicus; Inoceramus salomoni occurs in the base.
THE CENOMANIAN FERRIBY FORMATION (Flintless)
The Ferriby Formation is 22 metres thick at Melton Bottoms expanding to 35-38 metres at Speeton on the edge of the north eastern basinal deposits. The lower beds of the Northern Cenomanian with their extremely rare ammonite faunas and absence of glauconitic marl cannot be compared with those of Southern England and I.O.W., where ammonites and other fossils occur abundantly in the Glauconitic Marls. In the lower beds at Melton Inoceramus crippsi is common along with I. reachensis. Other fossils include Holaster subglobosus, Hemiaster griegenkerli, Schloenbachia varians, Hypoturrilites sp., Aucelina coquandiana and brachiopods.
Other main marker beds include the Totternhoe Stone, a tough grey gritty bed, and the source of many fossils including, bivalves, brachiopods, and the belemnites Actinocamax primus and Belemnocamax boweri, also Holaster subglobosus. The ammonites Austiniceras austeni and Hypoturrilites occur in the upper part. The overlying Pink Band contains Acanthoceras rhotomagense and Echinocorys sphaerica.
Other marker bands are the Nettleton Stone a thin bed of hard grey gritty chalk with a band of Pcnodonte vesicularis. The top of the Nettleton Stone Bed marks the base of the Holaster trecensis Zone. The top of the Ferriby Formation occurs at a burrowed erosion surface below the Black Band (Plenus Marls ). This thick black and khaki marly deposit represents a oxic/anoxic event traceable on a near global scale. The top of the Cenomanian is taken about 1 metre above. Actinocamax is rare in the conglomerate bed. Oxbirhynchia multicostata and Ornatothyris sp also occur.
THE WELTON FORMATION (TURONIAN) Mytiloides labiatus and Terebratulina lata Zones
The succeeding Welton Formation is about 53 metres thick. The basal 5m are flintless and include the Scigococeras gracile Zone at the base and approximately 4m of thinly bedded Myiloides labiatus chalk. The upper boundary is drawn just below the first line of flints. M. labiatus is abundant at specific horizons. Large inflated Parapuzosia (Austiniceras) austeni occur along with rare Mammites nodosoides. Both labiatus and Mammites have a worldwide distribution at this level. Echinoids include Conulus castanea and C. subrotundus. Terebratulids (Gibbithyris) and Orb. cuvieri are common.
The Terebratulina lata Zone is about 48 m thick, commencing 30 cm below the first main flint. The main bulk of the succession consists of massive bedded chalk with courses of nodular and burrow fill flints, becoming more thinly bedded towards the top where the boundary with the overlying Burnham Formation occurs. The main marker marls are those proposed by Wood & Smith (1978). These can be traced at a number of exposures North of the Humber including the much thicker sequences in Thornwick Bay and North Landing on the northern edge of the province.
Fossils are not common except in specific bands. Conulus subrotundus occurs on bedding planes along with thick shelled Gibbithyris semiglobosa in beds just above the first flint. Most of the massive chalk sequence is poorly fossiliferous (Barren zone of some earlier workers). Among the few species occurring are inoceramids of the brongniarti, cuvieri, lamarcki groups, found at specific horizons, particularly within the Barton Marls Group. The zonal index species Terebratulina lata, although not common, does occur as a ferruginous pseudomorph at a number of levels, with well preserved examples in higher beds. The occurrence of Inoceramus lamarcki geinitzi below the Deepdale Lower Marl marks a change in faunas, with the incoming of new species at the Welton/Burnham Formation boundary which occurs 0.8 metres below the Ravendale Flint.
THE BURNHAM FORMATION (Sternotaxis plana Zone Upper Turonian), (Micraster cortestudinarium and Lower Hagenowia rostrata Zones Coniacian)
Wood & Smith's description of the Burnham Formation from both sides of the Humber was incomplete due to the lack of suitable exposures in the Micraster cortest. and the upper part of the Lower Hagenowia rostrata Zones. The Micraster Zone was later, fully exposed at Willerby Quarry. The higher part of the Lower rostrata Zone is still not fully exposed above the Middleton Marl but the lower gaps have now been filled in.
The succession is erected from eight exposures, in ascending order above Welton Newbald Wold as follows, Newbald Wood, Kilnwick Percy, Enthorpe Rail Cutting, Willerby, Little Weighton, Eppleworth, Middleton-on-the-Wolds, and Selwicks Bay. (Including B/hole information 138-140m thick).
The base of the Burnham Formation below the Ravendale Flint coincides with the incoming of new faunas (well seen at Newbald). The first Sternotaxis plana appear 0.5m below the flint along with Micraster michelini, primitive Echinocorys, the earliest specimens of Infulaster excentricus (recorded by me) and Stereocidaris serrifera. Later species of inoceramids include Inoceramus inaequivalvis and I.lamarcki stumckeiji (both species identifying with the basal Upper Turonian sequence of the Salzgitter-Salder Quarry (Lower Saxony, Northwest Germany). It is proposed that the base of the Sternotaxis plana Zone is drawn here on the evidence of these new faunas, and also supported by the change from nodular to predominately tabular and semi-tabular flints.
The Triple Tabular Flints above the Ravendale Flint link the top of the Newbald section with the base of Kilnwick Percy (Warrendale Farm) which takes the succession up to the Ulceby Marl and Oyster Bed. Principle markers in this section include the North Ormsby Marl (identified with the Bridgewick Marls of Southern England and the ME 35cm Marl at Salzgitter Salder in N.W. Germany), the Ludborough Flint (3O-35cm), the Thornton Curtis Marl, with the ammonite Hyphantoceras occurring 1 m above (this also occurs at Salder in Germany). Above this level the twin Wootton Marls occur followed by the Ulceby marl and Oyster Bed which are also well seen at Enthorpe and North Landing.
The correlating coastal sections in Great Thornwick Bay and North Landing are approximately 20 % thicker than the inland sequences, due to basinal effects.
At the western end of Enthorpe Cutting the Ulceby Marl was proved after digging into the embankment, with the Ulceby Oyster Bed occurring about 3 metres above, linking with the top of Kilnwick. The sequence in the cutting exposes the upper 16 metres of the Sternotaxis plana Zone overlain by about 15 metres of beds in the lower part of the Micraster cortestudinarium [zone]. The beds between the Ulceby Marl and the next marker horizon (the Enthorpe Marls, a group of 4 over 3.5 m) are interspaced with a series of carious tabular and semi-tabular flints, yielding small Echinocoryrs, Micraster semiglobosa and crushed S. Plana.
Between the lowest two marls the first Sternotaxis placenta occurs and S. plana is absent in beds above this level. Infulaster excentricus and terebratulids also occur along with Pycnodonte vesicularis in the Enthorpe Oyster Bed.
About 4m above the Enthorpe Marls a further group of marls appear (the 3 Kiplingcotes marls spread over 2.8 m.). The Middle marl forms an important correlating horizon with the Salzgitter Salder Quarry sequence in N.W. Germany Immediately below the Kiplingcotes middle Marl a small bivalve Didymotis with a very limited range occurs and is correlated with Didymotis Upper Entry Event 2 in Germany and N W Spain. This level is also marked by the entry of the small inoceramid Cremnoceramus waltersdorfensis. Didymotis has been found only at Arras Road pit near Kiplingcotes by the author below the middle marl but C. waltersdorfensis is present at both localities. Above this horizon several new inoceramids appear along with an increase in echinoids. It also marks the extinction level of Sternotaxis placenta. The base of the Coniacian Stage is taken here tying in with the proposed International Standard Section.
This easily identified horizon marks a change in lithology from harder and some nodular chalks, to softer chalks (particularly at Enthorpe) coinciding with the appearance of numerous closely spaced tabular and semi-tabular flints, associated with a large influx of Echinocoryrs and Micraster and the inoceramids Cremnoceramus inconstans, C. schloenbachia, C. deformis, and I. lamarcki a little higher in the section. On the basis of this faunal evidence, the middle Kiplingcotes Marls is the proposed basal marker for the M. cortestudinarium Zone.
At Enthorpe the main markers for the M. ct Zone include the upper two Kiplingcotes Marls and the triple Kiplingcotes Flints. The latter spans 2 metres occurring in Kiplingcotes Station Pit and elsewhere. Above these flints there is a rapid change to more thinly bedded chalks with numerous closely aligned tabular flints. Early forms of Cremnoceramus inconstans occur associated with an increase in the numbers of Micraster and Echinocorys which reaches a peak in the Lower Echinoid Bed, 3 metres above the upper Kiplingcotes Flint. The highest recorded specimens of Infulaster occur 4 metres above this flint and may prove to be a new species.
Willerby Quarry (Burnham Formation) (Coniacian) Micraster Cortestudinarium zone.
At Willerby Quarry in 1977/78 the depth was increased to over 30 metres exposing a t « complete section of the Micraster cortest. Zone, from the Kiplingcotes Marls up to the Little Weighton Marls marking the upper boundary of the zone, and proving to be the key section linking Enthorpe, Kiplingcotes and Little Weighton for the first time.
The important correlating features are the basal Kiplingcotes Marls, and the Little Weighton Marls at the top of the section which correlate with the Little Weighton sequence.
A thin marl (the Kirkella Marl) occurs at about 15m and is overlain by a bed of large inoceramids of the I. lamarcki group (an horizon associated with N.W.Germany). The bed 1 m above marks the upper limit of Cremnoceramus inconstans and schloenbachi.
The lower Echinoid Bed occurs at a similar correlating level with Enthorpe, with an Upper Echinoid Bed some 14 metres above the base of the zone. Micraster bucailli and other forms occur, along with thick tested Echinocorys including elongated low forms. Several lesser horizons of echinoids are present in the higher beds. The highest Micrasters display a rugged angular test form and Echinocorys exhibits a flat top tendency. Apart from common inoceramids and echinoids, other fossils occur sparingly and include Gibbithyris semiglobosa, Orbirhynchia, and asteroid ossicles.
LITTLE WEIGHTON The succession continues at Little Weighton Quarry with the eastern exposure near Rowley Road exhibiting about 9 m of Upper M. cortest. beds overlain by about 20 m of Lower Hagenowia rostrata Chalk. The Upper Micraster Zone faunal and marl horizons correlate with the Willerby section. The base of the upper marl forming the boundary of the succeeding newly named Lower Hagenowia rostrata Zone.
The poorly fossiliferous basal beds comprise of massive hard flinty chalk with some thin shelly beds of fragmented involute inoceramids, seperated by a series of thin marls. The lowest bed above the L.W. Marl contains the inoceramid I. klieni. Higher beds yield Volviceramus koenini and involutus. Two dominant flints, the lower Eppleworth Flint (36.cm) and the higher, carious ferruginous De-la-Pole Flint, 5.5 m above, are exposed in the upper beds. Two bands of V. involutus spans the Epp. Flint.
The EPPLEWORTH QUARRY (type locality of Wood & Smith 1978) has a slightly higher section which is tentatively correlated with Middleton. The fauna and flints correlating with Little Weighton.
MIDDLETON-OB-THE-WOLDS (BURNHAM FORMATION)(CONIACIAN)(Lower H. rostrata ZONE)
At Middleton Quarry about 30 metres of Lower H. rostrata chalk is exposed with the lower face obscured by over 10 m of talus. During the course of this work a section about 1 m wide was cleared with the help of members of the Hull Geol. Soc. to enable correlation with the top of Eppleworth, extending the zone up by a further 24m. The sequence comprises of successive, massive bedded hard white chalks, divided by tabular, lenticular and nodular flints, with a conspicuous line of rounded and ball flints, occurring below the main marker (5cm Middleton Marl). Several other marls occur spread over 5 m above and below this horizon. Thinner paler palate flints occur near the top of the section. About 10 m of chalk overlies the Middleton Marl.
According to borehole evidence at Killingholme, Lincs, the flinty chalk extends to 40 m above the Middleton Marl, about 11m of this is seen on the south side of Selwicks Bay leaving a gap of about 19 m. By utilizing Lamplugh's (1896) High Stacks/Common Hole section of about 21.5m, the gap is reduced to about 9 metres.
Fossils include a band of Inoceramus digitatus just below the Middleton marl with Flamborough type sponges 2 to 4 m lower down. Volviceramus involutus was recorded from this pit, presumably from the basal beds which probably correlate with the involutus beds at Eppleworth and Little Weighton. Micraster coranguinum and brachiopods also occur.
LABGTOFT, BAINTON AND FLAMBOROUGH HEAD. (Burnham Fm.) (CONIACIAN) (Upper rostrata Z.)
The highest true flint in the Northern Province is visible at High Stacks and on the north side of Selwicks Bay, Flamborough Head, marking the top of the Burnham Formation and coinciding with the upper boundary of the Lower H. rostrata Zone.
Inland the boundary can be seen at Langtoft Quarry southwest of Langtoft. About 8.5 m of flinty chalk is overlain by 8 m of chalk without flints. A thin band of white pseudo flints occur in the base of Bainton (Bracken Quarry) but it is not known how high this level is above the true flints seen in Hornhill Top Quarry lying about 1 km to the south west.
The Coniacian/Santonian Stage boundary has yet to be defined in the Northern Province. In southern England and elsewhere in Europe the boundary is marked by the entry of I. Cladoceramus undulatoplicatus. This species has yet to be discovered in the Northern Chalk and most probably occurs in the unexposed chalk beds above Middleton Top. The overall thickness for the Ferriby, Welton, and Burnham Formations including the upper gap = 215 metres.
THE FLAMBOROUGH FORMATION
The stratigraphy is fully described for the first time in conjunction with a detailed account of the succession of the main macrofaunas. The massive thickness of the formation on land about equals the three lower formations. Three new members are introduced, South Landing, Danes Dyke and Sewerby, along with a sub-division of the Hagenowia rostrata Zone. Dates Suggested by nannofloral evidence are given for the upper part of the succession.
The formation comprises of approximately 215 metres of flintless chalk including some higher pits now filled in. The main part of the succession (165 m) occurs along the coastal sequence from High Stacks Flamborough Head to Sewerby Steps for 6.5 km, with higher parts exposed at inland pits and quarries.
THE SOUTH LANDING MEMBER, commencing at High Stacks and extending to South Landing, is 26 m thick, consisting of extremely hard, massive white chalk, thinning near to the Landing.
THE DANES DYKE MEMBER, occurs between South Landing and Danes Dyke and is approx 66 m thick, with thinner bedded hard and softer chalks and numerous closely spaced marls, gradually changing back to more thickly bedded chalks with some stylolitic horizons in the upper part where thicker marl bands provide useful markers.
THE SEWERBY MEMBER, commences from the west side of Danes Dyke up to Sewerby Cliff Steps and includes the inland sections (exposed part 123 a thick). The member is characterized by more massive bedded chalk, softer than in the previous members, interspaced with some thinly bedded sequences, and many more stylolitic horizons. More numerous thicker marls also occur.
Biozones along the coastal succession are the newly introduced Upper Hagenowia rostrata Zone commencing at High Stacks Flint, followed by, Uintacrinus socialis, Marsugites testudinarius, Inoceramus lingua, and the Discoscaphites binodosus subzone, the latter occurring above the Sewerby Steps and at higher inland exposures. The presence of numerous marl bands in the Flamborough Formation (239 in 195 m of chalk) is in marked contrast to numbers in the three lower formations (83 in 215 m of chalk).
A total of 32 of the thicker more persistent marls are selected as markers.
South Landing Member (Santonian).
The base of the Formation commences at the High Stacks Flint Flambro Head, this also coincides with the base of the South Landing Member and the Upper Hagenowia rostrata Zone, which extends along the coast westwards for about 3 km to South Landing exposing about 26 metres of Upper rostrata chalk. The upper boundary of the member is taken at the top of the East Nook Marl which is present on both sides of the Landing and underlain by a burrowed horizon about 1 m below. Thinner bedding occurs in the cliff at the east side of the Landing. The middle part of the sequence shows little dip lying almost horizontal for over 2 km. The average frequency of marl occurrence within the member (about 20 in 26 m of chalk) is 1.3 m. Fossils are scarce except in bands, the main ones being Gonioteuthis granulata, Actinocamax verus, a band of Hagenowia blackkmorei anterior, common Porosghaera globularis, Orbirhynchia pisiformis, occasional Echinocorys sp., fragmented inoceramids and a few sponges, other exposures inland are Langtoft and possibly the base of Bainton (Bracken pit).
Danes Dyke South Landing West. (Upper rostrat.) (Uintacrinus) (lower M. cortest.)
The basal bed of the Danes Dyke Member commences at the top of the East Nook Marl on the West Side of South Landing dipping down to shore level within a short distance from the ravine. The member extends due west for about (1.5 km) and is [66 m) thick. The upper boundary is taken at the top of the k cm Danes Dyke Upper Marl occurring close to Danes Dyke.
Biozones within the member comprise of 22.5 m of the upper H. rostrata Zone, 29m of the Uintacrinus socialis Zone, and 14.5 m of the lower half of the Marsupites testudinarius Zone. Lithological changes from massive bedding to thinner sequences previously described are apparent. Some thicker marls in parts of the succession provide useful markers, two of the most important are the Lower and Upper Beacon Hill Farm Marls about 4.5 « apart and 20 to 25 m above the base of the member, they span the Uintacrinus basal boundary which occurs about 2 m above the Lower 8 cm marl, by far the thickest within the member.
The higher part of the rostrata chalk within the member is divided by about 45 marls and is approx 22.5m thick giving an average occurrence every 0.5 m compared with 1.3 m in the lower part of the zone in the South Landing Member. Several bands of Hagenowia blackmorei occur in the lowest 2 to 3 m of the Danes Dyke member. Its relative abundance is generally confined to a fairly narrow range on both sides of the Landing. However this species is said to occur in the cliff 100m from Sewerby Steps in the lingua Zone and is recorded at East Leys much higher in the sequence. The remainder of the fauna is restricted to Echinocorys sp., Gonioteuthis granulate, rare brachiopods, fragmented inoceramids and Flambro type sponges.
UiNTACRINUS Socialis ZONE (DANES DYKE MEMBER) SANTONIAN.
The base of the Uintacrinus Zone occurs 2 m above the Lower Beacon Hill Marl about 500 m from South Landing and is about 29 m thick, being thinner bedded in the lower part. 31 marls occur within the zone and 7 of the thicker more persistant are named as successive markers.- Upper Beacon Hill Farm Marl, (4 cm). Hartendale Marl (2 cm reaches beach level on west side of Hartendale Gutter), Maidland Lower Marls (2-3cm), Maidland Upper Marls (2 cm).
Isolated plates are abundant at specific horizons with very rare occurrences of complete cups of the zonal index species. The plates gradually diminish towards the top of the zone, and disappear about 3 m below the upper boundary. This species is comparatively rare inland. Other fossils include Sphenoceramus pinniformis, flat topped Echinocorys var. tectiformis and a straight sided test species appearing to E. planodoma, Gonioteuthis granulata, Pycnodonte boucheroni, O.gisiformi and Flamborough type sponges.
Inland at Beverley a suggested correlation is made with the coastal sequence, at a 5 cm marl horizon which may correlate with the Upper Maidland Marl 'B' on the coast, as a single smooth plated calyx of Marsupites (the lowest recorded inland) has been found just above this marl at Queensgate Quarry.
MARSUPITES testudinarius ZONE (LOWER PART) (DANES DYKE MEMBER) SANTONIAN.
The thickness of the Marsupites Zone on the coast is about 26 m. The lowest 15 m forms the top of the, top of the Danes Dyke Member. The base of the zone is taken at the top of Upper Maidland Marl 'B’, coinciding with the first appearance of fairly rare and isolated Marsupites plates in the overlying bed. Softer more massive chalks are present and, several, more prominent marl band groups, form useful markers which are named, The Danes Dyke Lower, Middle, and Upper groups. Calyx plates of the Zonal fossil are rare in the Danes Dyke Member both on the coast and inland. Other fossils are not common, being restricted to Gonioteuthis granulata, crushed examples of Echinocorys ? var. tectiformis and sponges.
By comparison, the inland sequence at Beverley is more fossiliferous and exhibits many stylolitic bands. Echinocorys var. elevatus and Ech. var. tectiformis occur in a band about 2 m above the base of the zone. Gonioteuthis is common 6 m above the base and the large ammonite Parapuzosia also occurs.
SEWERBY MEMBER (MARSUPITES test. ZONE (UPPER PART) SANTONIAN.
The top of the Danes Dyke Upper Marl forms the base of the Sewerby Member which extends along the coast from Danes Dyke West to just beyond Sewerby Steps, terminating at the well known Sewerby Buried Cliff section of Lamplugh (1888). Higher beds in the member occur inland.
The sequence dips south west exposing the remaining upper 11 m of the Marsupites Zone and 60 m of Inoceramus lingua Zone beds, of which, the upper 3m is assigned to the Discoscaphites binodosus subzone. The base of the member is marked by the appearance of thinly bedded chalks, more massive chalks appear in the lingua Zone, interspaced with some softer thinner bedded sequences which occur more frequently in the Sponge Beds.
In the upper part of the Marsupites test. Zone, isolated calyx plates are common on the beach scars close to the west side of Danes Dyke, and occur abundantly, together with occasional complete calyces about 100 m further west. This flood of the zonal fossil is spread over about 5 m of chalk with the greatest concentration in the middle part, before dying out close to the zonal upper boundary. Other species occurring within this part of the zone include occasional specimens of Echinocorys var. tectiformis, large examples of Gonioteuthis granulata/quadrata with a deeper alveolus, Orbirhynchia pisiformis, radiating sponges, Sphenoceramus pinniformis asteroid ossicles and echinoid spines.
Inland at Queensgate Beverley, the upper 8.5 m of Marsupites chalk is tentatively assigned to the Sewerby Member, having a similar lithology to the coastal section. About 3 m from the top, early examples of Inoceramus lingua appear and are associated with Sphenoceramus pinniformis (the presence of lingua is indicative of the upper part of the Marsupites Zone). Radiating varieties of Ventriculites in the form of oxide films and other sponges along with large distorted Echinocorys var.tectiformis also occur. Belemnites and calyx plates are absent from these beds, but are common about 8 to 10 m below, where complete calyces occur and large belemnites are present. Acutostrea boucheroni common in bands. If Inoceramus lingua indicates the top of the zone inland, the thickness would be 21.5m compared with 26 m on the coast, showing a similar percentage reduction (20%) to that of the Turonian Chalk.
INOCERAMUS lingua ZONE (SEWERBY MEMBE)(LOWER CAMPANIAN (LOWER PART)
The remaining 60m of chalk in the coastal region and higher beds inland (possibly 45 to 50 m) belong to the I. lingua Zone. Wright & Wright (1942) proposed a subzone of Discoscaphites binodosus for the upper part of the zone above Sewerby Cliff. Macrofaunal evidence indicates a Lower Campanian age for these beds, although recent nannofossil determinations from marl samples suggest the highest beds exposed may be of Upper Campanian age. This is discussed later.
The base of the I. Lingua Zone occurs at a bedding plane 2 m above the last appearance of Marsupites and is marked by a profusion of fragmented shells of I. lingua in the overlying chalk bed. This horizon also marks the junction of the Santonian/Campanian Stages, occurring about 200 m west of Danes Dyke. About 50 marls occur in the 60 m of coastal lingua chalk, with an average frequency of 1.2 m. They include an increased number of thicker marls up to 9 cm. The lowest and thickest 9 cm Daneswood Marl occurs about k m above the basal boundary and is succeeded by the Daneswood Middle (4cm), and Upper 5 cm Marls. The 3 cm Longwood 6cm occurs high in the Sponge Beds. The Marton Hall 4 cm, Sewerby Hall 4 cm, and Sewerby Steps 6cm Marls follow in sequence, the latter occurring halfway up the steps, marking the boundary of the Discoscaphites binodosus Subzone.
Fossils are more common, with I. lingua the dominant bivalve and rarer examples of Sphenoceramus pinniformis and patootensis, the latter occurring higher in the succession. Sponges reach their finest development and are common in the famous Flamborough Sponge Beds which extend to over 10m in thickness. The base lies 15.5 m above the zonal lower boundary and 122 m above the base of the Formation. Due to a shallower dip where the Sponge beds reach shore level, the beds continue to be exposed on the beach scars for a considerable distance, commencing about 350 m from Danes Dyke. The main exposure lying nearer to the Dyke than to Sewerby. A large number of species are identified. Large domed thick tested Echinocorys sp (up to 80 cm long) occur in thin bedded sequences in the Sponge Bed becoming less common in higher beds on the coast. The top of the Sponge beds is marked by 3 thinly bedded horizons with intervening bands of Acutostrea boucheroni spread over about 1.5 metres.
Belemnites of the Gonioteuthis granulata/quadrata lineage are fairly common becoming rarer higher up. The development of this cephalopod group can be traced from the base of the Formation at High Stacks up to the highest inland exposures, a thickness of over 200 m. From work carried out on a very restricted number of individuals, (as their occurrence is not common in some parts of the succession) it has been possible to record the increase in the depth of the alveolus on successive specimens collected stratigraphically. The details can be seen on a later slide.
Other fossils include very rare Offaster pilula (not seen by me), Cardiotaxis sp, Hypoxytoma tenuicostata, Salenia sp. and rare ammonites Haurericeras, and Scaphites sp.; Hagenowia is reported 100 m from Sewerby Steps.
The Sewerby Steps Marl (occurs at the upper part of the steps close to the top of the Sewerby Cliffs sequence), the Sewerby Hall Marl (4 m below) and the Lower Daneswood Marl (9 cm base of I. lingua Zone) were analysed by Dr Jackie Burnett of University College London to determine their calcareous nannofossil content for biostratigraphical comparisons with problematic inland sequences.
The following age determinations are given in ascending order,
Sample 1. (9 cm Daneswood Marl base of coastal lingua Zone) Probably late Santonian to early Campanian.
Sample 2. (4 cm Sewerby Hall Marl) Early Campanian.
Sample 3. (6 cm Sewerby Steps Marl) Apparently Late Campanian.
The 3 marls yielded 45 species excluding co-occurring types. Sample (3) gives the most contrversial dating as it occurs 4 m above sample (2) which is of Lower Campanian age.
RUSTON PASVA (LOWER CAMPANIAN) LOWER/MID I. lingua ZONE.
One other important inland exposure in the lower/mid lingua Zone is at Ruston Parva where 30 m of chalk is exposed. 3 marl samples from the lower, middle and upper beds were examined for their nannofossil content including the lowest 6 cm marl, an upper 3 cm marl and a 2 cm intermediate marl. 58 species were recovered excluding co-occurring types. Unfortunately the age could only be determined as Campanian . Whilst this correlation was not conclusive with the coastal section, the massive beds with a number of thick marls seen at Ruston Parva, closely resemble the higher part of the coastal sequence. The Sponge Bed sequence is absent, and there is no indication of the thick Inoceramus lingua shell beds seen on the coast. The rather sparse fauna compares with that above the coastal Sponge Beds. Further correlative evidence is provided by the marl horizons, the 6 cm Ruston Parva basal marl is provisionally correlated with the 6 cm Longwood Marl high in the Sponge Beds on the coast, placing the Ruston Parva sequence in the higher part of the succession below the Sewerby Steps Marl.
SUNZONE OF DlSCOSCAPHITES binodosus (LOWER CAMPANIAN UPPER PART) I. Lingua Zone
Chalk above the Sewerby Steps Marl (dated Late Campanian) marks the base of the Discoscaphites binodosus Subzone as the zonal fossil occurs above this level. This horizon is also taken to mark the upper part of the Lower Campanian Stage, a proposal partly based on nannofloral changes, and by the incoming of species of Echinocorys and Micraster, species which appear to relate to those recorded in the upper part of the Lower Campanian Stage in N.W. Germany. The Sewerby Steps Marl provides a suitable horizon at which to draw the boundary.
At present only two inland exposures of any significance remain where higher chalk of the Discoscaphites Zone can be observed. These are at the large Nafferton Grange Quarry 17 km south west of Sewerby, and at Bessingby Pit on the S.W. outskirts of Bridlington. A more recent exposure during the building of the new Bridlington Hospital exposed similar beds to those of Bessingby Pit, and containing numerous inoceramids, scaphitid ammonites and some sponges. Higher chalk was previously exposed at White Hill and East Leys Farm to the north of Bridlington, but these pits are now filled in and there are no stratigraphical records.
The limited exposures in the D. binodosus Subzone make it difficult to erect a sequence for the inland succession. The gap between the top of Sewerby and the base of Nafferton is not known. Although the Sewerby Steps Marl is not present at Nafferton, the chalk facies is little changed from that of the highest coastal beds, in addition belemnites recovered from the base of the quarry with an alveolus depth of about 18 mm are deeper by about 2 mm in comparison with those from the coastal Lower Campanian.
This line of evidence suggests that the gap may be small, deeper quarrying in the future may link, these two sections.
NAFFERTON GRANGE (DISCOSCAPHITES binodosus S/ZONE) LOWER CAMPANIAN (UPPER PART)
At Nafferton the exposed 25 m of chalk is divided by a rhythmic series of 22 marls of which, 9 are over 2 cm thick. Although no longer worked, there are 3 working levels, each with a group of marker marls. Lower (Group of 3, 2 cm A-B-C in 4 m of chalk), Middle (5 cm Marl 'D'), and Upper (Group of 3, 3-4-5 cm E-F-G), Part of the Upper group correlate with Bessingby marl 'G' proving to be of the same age as the Bessingby Marl with the co-occurrence of Echinocorys var.subconicula, providing further evidence.
Samples from 3 selected marls (Lower 'A’, Middle 'D', and Upper 'G’) were examined by Dr Burnett to determine their calcareous nannofossil content. A total of 65 species excluding co-occurring forms were recovered
Sample 1. (Lowest 2 cm Marl 'A') Fauna suggests a probable Middle/Late Campanian age.
Sample 2. (Middle 5 cm Marl 'D') Fauna indicative of Middle Campanian age.
Sample 3. (Upper 5 cm Marl 'G') Fauna suggests Late Campanian age.
This nannofloral evidence provides further support for a later age dating of the Campanian chalk above Sewerby Steps Marl, up to Upper Marl 'G' at Nafferton. However beds above Nafferton Grange Upper Marl 'E' contain species of Echinocorys Var. subconicula and Echinocorys var. subglobosa which are usually associated with the Upper Part of the Lower Campanian chalk of N.W. Germany. The former species occupies a similar position in the chalk of Southern England.
At the present time there are no known in situ macrofaunas to confirm the presence of Upper Campanian chalk in the Northern Province although belemnites recovered from the drift indicates chalk of this age floors the North Sea.
Other fossils include Echinocorys ? var gyramidata, Micraster schroederi, Micraster glyphus n. sp. [sic] , Inoceramus lingua, Cataceramus balticus, Sphenoceramus gatootensis and a radially ribbed species ? Sphenoceramus steenstrugi. Flamborough type sponges also occur, along with small brachiopods and other fossils.
BESSINGBY PIT (DISCOSCAPHITES binodosus S/ZONE) LOWER CAMPANIAN (UPPER PART)
The Bessingby Pit and the New Hospital site yield similar faunas with echinoids correlative with the top of Nafferton. Bessingby has also produced a fine specimen of Gonioteuthis quadrata with an alveolus depth of 22 mm.
This slide shows the relative suggested positions for the inland sections compared with the upper part of the Sewerby Cliff section.
The gradual deepening of the alveolus from 4 mm at the base of the Formation to 22 mm in the highest part, reflects the evolutionary development in Gonioteuthis.
Based on an estimated time scale in Rawson et al. 1978 and Ernst & Schmid (1979) of approximately 4.5 million years for the Mid/Upper Santonian to Lower Campanian Stages, the deepening of the alveolus in the Gonioteuthis/granulata/guadrata lineage approximates to about 1 mm per 250,000 years, and equal to 1 mm in 10. 83m of Northern Province Chalk. In this table, belemnites from drift deposits and other sources are used for comparison purposes in the Upper Campanian Chalk.
Sincere thanks are due to Dr Peter Rawson, University College London, for his help and most constructive criticism of the original manuscripts, and to Professor John Neale who read an earlier manuscript. Grateful thanks are also due to Dr Jackie Burnett University College London for her invaluable analysis of the nannoflora, and to those members of the Hull Geological Society who have helped in various ways with this project, particularly Mike Home and Lynden Emery.
To conclude: A cautionary tale. A friend posed the question: Did I know what caused the extinction of the Dinosaurs? After confessing to my ignorance on the subject, I was reliably informed they died of boredom looking at the chalk.
[scanned & edited MH August 2010]
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