Upper Cretaceous Chalk Stratigraphy with some Faunal Horizons
North of the Humber North Eastern England
SUMMARY: In the past various estimates have been made about the total thickness of the Yorkshire Chalk succession and more recently measured lithostratigraphical sections of the lower and middle Ferriby, Welton, and Burnham Formations, plus a suggested 300 metres for the overlying Flamborough Formation, gave a total figure of about 500 metres. Over a period of 30 years the author has measured, and recorded numerous exposures. Unfortunately some of the most important sites have now been filled in.
This paper is intended to give a bed by bed description of chalk types, flint horizons, marl bands, and in situ faunas for most of the exposed, accessible Yorkshire succession covering over 400 metres, and is erected from a number of inland exposures for the three underlying formations, with sections from High Stacks to Sewerby, on the coast, along with several inland sequences completing the higher Flamborough Formation.
The huge thickness of the Flamborough Chalk exposed on land almost equals the combined totals of the three lower formations and the main lithological changes within the formation are best seen along the coast - (High Stacks to Sewerby) and occur near two naturally situated ravines. It is therefore proposed to introduce three new members within the Flamborough Formation namely, South Landing, Danes Dyke, and Sewerby. A new zonal division is introduced at the flinty/flintless chalk horizon, and the boundaries and key markers are described for both these proposals.
Nannofossils recovered from marl bands in the highest exposed inland chalk suggest a Middle and Upper Campanian age for this part of the succession, formerly thought to be of Lower Campanian dating. Particular importance is placed on the biostratigraphical succession of some key fossil groups.
One of the earliest recorded measured sections of the chalk North of the River Humber appears to be one made by W. Hill in 1888 when he described about 70 feet of Cenomanian Chalk in South Cave Railway Cutting. Other contributors to the Yorkshire Chalk succession include Jukes Brown and Hill (1903) Rowe A.W. (1903) Wright and Wright (1942) Jeans C.V. (1973) Wood C.J. and Smith E.G. (1978) Rawson P.F. et al. (1978) Wood C.J. (1980).
Although Wright C.W. and Wright E.V. (1942) zoned most of the inland pits cut in the chalk, making an outstanding contribution to our knowledge of the Northern Chalk Province, no detailed measured sections were published. Jeans C.V. (1973) measured Cenomanian exposures at Speeton, and Wood and Smith (1978) did publish a detailed account of the lithostratigraphical succession of the lower half of the Northern Chalk. They erected a stratigraphical group consisting of four formations in ascending order (Ferriby, Welton, Burnham, and Flamborough), as they considered the standard tripartite classification of the Northern Province Chalk into Lower, Middle, and Upper divisions (Derived from the Southern succession) could no longer be justified on either lithological or palaeontological grounds. Their proposed formations encompassed and tied in with the former biostratigraphical sequences almost exactly with a few exceptions. The Ferriby and Welton succession was continuous from the basal Albian Red Chalk, embracing the Cenomanian sequence, and the Turonian up to the highest beds of the Terebratulina lata Zone. In the overlying Burnham Formation the lower part is occupied by the remainder of the Turonian Stage with beds forming the whole of the Sternotaxis planus Zone. Due to the lack of inland exposures at that time, Wood and Smith were unable to complete the upper part of the Burnham Formation, and did not describe any stratigraphical details of the overlying Flamborough Formation. Although their work and the publication of a generalized section of the Chalk Group in Northern England is based on a number of overlapping sections in Lincolnshire and Yorkshire, it is well founded and can be followed in succession to the higher parts of the Burnham Formation in exposures located entirely North of the River Humber.
1. THE STRATIGRAPHICAL SEQUENCE
In the present paper the aim is to depict a lithostratigraphical column of the Northern Province Chalk succession from the basal Ferriby Red Chalk, up to the highest known beds occurring on land in the Flamborough Formation. (Figures 3 & 16). The exposures which make up the stratigraphy are individually described, and illustrated giving details of bedding sequences, lithology, fossil occurrences, and major flint and marl marker horizons. The named positions in the Ferriby, Welton, and Burnham Formations, are those established by Wood and Smith (1978) with minor exceptions, where new beds have been introduced. The Flamborough Formation is fully described in detail for the first time, with a number of newly named marker beds for this higher part of the chalk.
The basal Albian Red Chalk and Cenomanian Stage (Ferriby Formation) described in this account is from the exposures at Melton Bottoms which apart from some thinning, particularly in the Red Chalk (South Ferriby 3m thick, Melton 1.5m.) is in most respects similar to that at South Ferriby and a number of other localities in N. Lincolnshire, where the thickness of the Cenomanian varies between 22 and 24 metres and the boundary between the two stages is well defined, whereas at Speeton in the North of the area the definition is not clear as the red colour continues up into the lower part of the Cenomanian Chalk. Different authors in the past have given varying figures for the thickness of the Albian Chalk ranging between 13 and 15 metres, and for the Cenomanian from 35 to 38 metres. These very much thickened deposits appear to be associated with the Cleveland Basin and a satisfactory stratigraphic relationship with the more southerly exposures in Humberside and N. Lincolnshire has yet to be formerly established. For this reason the Speeton succession is excluded from the stratigraphical sequence.
The deepened depositional area observed at Speeton extends South Eastwards to the section seen at both Little, and Great Thornwick Bays and North Landing, where Turonian Chalk in the Terebratulina lata and Sternotaxis planus Zones, exhibits a much thickened successive series of chalk beds including the same correlating flints and marls as those seen at exposures further South in N. Humberside (Fig.7). The difference in thickness between the North and South facies is about 9.7 metres, when measured from the lowest of the Barton Marls up to the Ulceby Oyster Bed. This much thicker sequence of Turonian Chalk appears to be confined to the North Eastern part of the County, and is in sharp contrast to the more uniform, constant deposition South of Market Weighton, extending across the Humber and into Lincoln shire. This thicker sequence is also excluded from the lithological succession, (Fig. 3).
The Ferriby Formation previously well exposed at Melton Bottoms (Fig. 4) includes the basal bed of the underlying Red Chalk where it rests on the Carstone. The upper boundary is taken at the erosion surface below the Plenus Marls (Black Band) (Wood and Smith 1978). The overlying Welton Formation chalk is still worked at Welton Wood (Fig.5), this location was nominated the stratotype of the previous authors and the facies now exposed, extends the chalk up to the basal marker beds of the succeeding Burnham Formation.
In North Humberside the Burnham Chalk succession is erected from a number of exposures in continuous upward sequence commencing with Newbald Wood Pit, (Fig.6) Kilnwick Percy (Fig.6), and Enthorpe Rail Cutting (Fig. 8), embracing the whole of the Sternotaxis planus Zone, and the lower part of the Micraster cortest. Zone. Willerby Railside Pit (Fig. 9) is fully described in the relevant text for the first time following quarrying operations which took place in the late nineteen seventies, exposing a complete sequence of the Micraster cortest. Zone, and some chalk horizons not previously seen inland in the Northern Chalk Province, proving to be a key section, and making it possible to complete the gap up to the Eppleworth Flint at Little Weighton Quarry (Fig. 10).
Excavation work carried out by members of the Hull Geological Society in digging out the thick talus at the base of Middleton Quarry (Fig. 13) enabled correlation to be made with the top beds in Eppleworth Quarry (Fig. 11) thus proving continuous succession from the basal Ferriby Red Chalk up to the Burnham Chalk, Middleton Marl, at the same time filling in the previous gaps and extending the flinty chalk of the Lower Hagenowia rostrata Zone in upward unbroken sequence for over 40 metres (Fig.3). The rest of the chalk succession in the flinty part of the Zone up to the highest true flint is poorly known in the Northern Province due to lack of exposures inland and the inaccessibility of the coastal section. Recent borehole evidence from North Lincolnshire extends the flint bearing chalk approximately 40 metres above the Middleton Marl, this thickness is taken into consideration in the gap near the top of the Burnham Formation (Fig. 3) the boundary being marked by the highest true flint level. This flint horizon is well seen at beach level near High Stacks, and the North side of Selwicks Bay at Flamborough Head. At the latter locality about 11 metres of chalk with flints is present in the cliffs on the South side of the bay and a complex fault zone occurs between the North and South points.
Lamplugh (1895) described beds in the cliff section from High Stacks to Common Hole and gave details of over 70 feet (21.5 metres) of flinty chalk up to and including the top flint (Fig. 3). Parts of this sequence are only accessible from the sea and are not confirmed by the author. The only other known exposures where the boundary between flinty and flintless chalk occurs, are well exposed at Bainton Balk Pit (Fig. 14a) which shows a band of thin flints just above the present base, and the section at Langtoft (Fig. 14b) exhibiting about 8.5 metres of flinty chalk overlain by up to 8 metres of chalk void of flint.
The overall thickness of the chalk with flints taken from the basal first main flint at Melton (Fig. 5) up to the top flint at High Stacks (Fig. 3) is about 185 metres, with approximate figures for the Burnham Formation of 138 to 140 metres and for the flinty lower chalk of the Hagenowia rostrata Zone 73 to 75 metres. The deep cored borehole at Reckitt and Coleman, Hull (Wright & Wright 1942) showed 525 feet (160 metres) of chalk with flint beds overlain by 56 feet (17 metres) of alluvium and drift. Although it is not certain the uppermost flint seen on the coast, occurs at a constant horizon (Wood 1980), in the present authors opinion it would appear reasonable to accept it probably does so within certain confines. It is therefore proposed to divide the present Hagenowia rostrata Zone by using the term "Lower" to define the flinty chalk and "Upper" for the overlying flintless chalk. This lithological division can also be supported by changes in the zonal echinoid H. rostrata which is comparatively rare in the exposed flinty chalk and does not extend up into the flintless chalk characterised by an abundance of H. blackmorei anterior (Wood 1980).
It is not possible to define the Coniacian / Santonian boundary in the Northern Chalk at the present time, which in Southern England is defined by the entry of the inoceramid Cladoceramus undulatoplicatus (Roemer) and the horizon marked by the Michel Dean Flint of Mortimore (1986).
Although this species has not been observed in the North by the present author it may well occur in the unexposed part of the upper flinty chalk succession this same observation could also relate to the apparent scarcity of the zonal species of Micraster, as very little is known about the 30/40 metres of this higher part of the flinty chalk sequence. It is therefore suggested a provisional and easily identified provisional boundary be taken at the highest flint coinciding with the top of the Burnham Formation, pending the development of suitable exposures sometime in the future.
The basal beds of the stratotype for the succeeding Flamborough Formation occur at High Stacks on the South Side of the Headland and overlie the top flint exposed at beach level. (Wood and Smith 1978). Their account gave only brief details of the land based sequence, which as a result of this present work has a known thickness of about 156 metres along the coastal strip from High Stacks to a short distance beyond Sewerby Steps (Fig. 16). This part of the succession includes the flintless Upper H. rostrata Zone (Figs. 18 & 19), the Uintacrinus socialis, and Marsupites test. Zones (Figs. 19 & 20), and the lower two thirds of the Inoceramus lingua Zone (Figs. 22 & 23) (The local equivalent of the 0. pilula Zone).
Deep ravines dissect the chalk cliff at South Landing approximately two miles (3.2km) from High Stacks, and at Danes Dyke about one mile (1.2km) further West. The boundaries of two of the proposed new members occur in close proximity to the named naturally occurring land features along this sequence and are appropriately nominated South Landing and Danes Dyke, the Sewerby member taking its title from the nearby village of Sewerby. (Fig. 16).
The Chalk of the Flamborough Formation is marked by a complete absence of flint and is extremely hard in the basal part of the Upper H. rostrata Zone, becoming less so in the succeeding zones. Many marl bands are present, being more frequent at some horizons than others leading to thinly bedded and massive beds of chalk. Stylolitic bedding planes are most common in the Marsupites Zone. Fossils occur in some abundance at specific horizons particularly inoceramids, sponges, certain species of echinoids, with many scaphites ammonites in the highest beds of the formation, although in the lower part there are bedding sequences where the chalk is almost barren. The stratigraphy with fossil horizons for the coastal section is depicted in Figures 18-19-20-22-23, and are fully described in the relevant text's.
There are few good inland exposures in the formation, the only ones of any note are best seen at the following localities, Bainton Balk (Fig. 14a), Langtoft (14b), Queensgate (Fig. 21) and Ruston Parva (Fig. 24). These sections are discussed in the appropriate paragraphs. The highest beds along the coast in the I. lingua Zone are at Sewerby Steps. Part of this sequence occurs inland at Ruston Parva, which according to Wright and Wright (1942) is in the lower part of the Zone. This position is still not clear, and it is hoped, further work on micro faunas will help to resolve this problem.
Only two other locations worthy of consideration, and exhibiting chalk beds higher than the Sewerby Steps section are now available for study. They are at Nafferton Grange (Fig. 26) (Wrights’ Pit 96c), and Bessingby (Fig. 25) (Wrights’ Pit 108). Both these pits were placed in the Discoscaphites binodosus sub Zone erected by the Wright Brothers. Previously higher beds in the zone were quarried at White Hill and East Leys (Wrights’ Pits 109 & 110). Unfortunately these pits and many others are now filled in, making correlation of the upper part of the Zone very difficult if not impossible. Recent work on nannofossils in marl samples from Nafferton Grange, taken at lower, middle, and upper levels, suggest a lower to middle Campanian dating for the two lower marls, and a late Campanian age for the highest marl. The samples from Bessingby are of equivalent late Campanian age and comparable with the top beds at Nafferton. The stratigraphical succession for the formation (Fig. 16) depicts the actual exposures at the present time, the total thickness of the higher beds to the North of Bridlington is not known, this also applies to the gaps shown in the respective figures. It is possible that an estimated further 25 to 30 metres could be added to the known thickness of the formation, which at the present time, based on measured sections is approximately 190 metres.
2. THE FERRIBY FORMATION
The stratotype Ferriby Formation of Wood and Smith (1978) was based on the section at South Ferriby in the Rugby Cement Company's quarry (SE 991204). The present description is confined to the chalk sequences North of the Humber, and the beds described here are from the huge quarry at Melton Bottoms (Fig. 4) (SE 973273), taken at a time when chalk extraction was at a peak. The workings are now no longer in use, and the sides of the pit have been scaled down for safety reasons, as a result the previously very good exposures are totally obscured, although the stratotype on the South Bank of the Humber at S. Ferriby is still accessible at the present time.
The formation at Melton is approximately 23.5 metres thick, and extends from the base of the 1.5 metres of Red Chalk to the erosion surface below the Black Band, which at this location, includes 22 metres of Cenomanian Chalk (Fig. 4) .Quarrying first started in 1958 and subsequent operations exposed the following descending sequence, 7 metres of Lower Turonian Chalk (Basal Welton Formation), a fractured and contorted Cenomanian Stage, resting on an attenuated, Upper and Middle Albian Red Chalk sequence, with underlying beds of Lower Albian Carstone, (Owen, Rawson and Whitham 1968), in direct unconformable contact with a thick sequence of Corallian Ampthill Clay. At one stage a number of huge bulges extruding from these clays, and thrusting upwards at a steep angle were exposed in the working face, lifting the overlying beds in a series of wave like structures, a feature which could clearly be seen in the displacement of the Plenus Marls (Black Band) in the upper part of the Cenomanian Beds. This phenomenon is thought to be due in part to tectonic activity within the area of the Humber, leading to a process of vertical and diamond fractures within the chalk bedding, lending to considerable weakness, accentuated by the upward squeezing of the underlying clays, probably caused by pressure from the enormous weight of the overlying Welton Wood Turonian Chalk, (Welton Formation of Wood and Smith 1978) some 54 metres thick just above and behind the Melton Quarry, close to the line of weakness. A similar though not as severe disturbance is described from the South Bank of the Humber at S. Ferriby (Smart and Wood 1976). These analogous features appear to be confined to the Humber area.
2.1. Albian Red Chalk
The Red Chalk is an impure red and pink limestone, nodular in parts, and contains polished pebbles in the lower beds, the basal 10cm consisting of a red clay which grades into the underlying Carstone. This clay bed has yielded a single whorl fragment of the ammonite Dimorghoglites cf. hilli Spath a species described by Spath in (1926) from the basal Red Chalk at Hunstanton (now Hunstantan Red Rock or Limestone Formation) and was later (Spath 1942) listed from the Anahoplites intermedius subzone. Although no evidence was given for this more precise dating, forms relating to D. hilli occur in the Upper part of the Hoplites dentatus Zone of Southern England suggesting that part of this Zone of Middle Albian age is represented in the Melton Red Chalk. More recently a fragment of Anahoplites sp. has been recovered from these beds, and the thicker sequence at S. Ferriby yielded a specimen of Mortiniceras (M) inflatum (J. Sowerby) M. inflatum Zone from the upper pink beds of the Red Chalk, found by the author and described in Smart and Wood (1976). From these records, it would appear to confirm that parts of both Middle and Upper Albian stages are represented in these basal chalk deposits on both banks of the Humber. There is a gradual passage down into the Carstone, through the red clay bed from the over lying chalk series.
The top 15cm. of the underlying Carstone contains a fauna comparable with that of the Shenley Limestone (Lower Albian) at Leighton Buzzard and includes the brachiopods, Burrirhynchia leightonensis (Walker), Cyclothyris mirabilis (Walker), and Modestella festiva Owen. The rest of the fauna from the same horizon consists of small bivalves including, Entolium orbiculare (J.Sowerby), Exogyra latissima (Lamarck), Lopha colubrina (Lamarck), and Neithea sp.indet. Varieties of the belemnites Neohibolites minimus and N. attenuatus are also present (Owen, Rawson & Whitham 1968). The Red Chalk is very fossiliferous, the dominant species being confined to belemnites and brachiopods. Several varieties of N. minimus and N. attenuatus are abundant and well preserved in the basal clay bed, occurring sporadically in the rest of the chalk. Moutonithyris dutempleana (d'Orbigny) is the most common brachiopod, other species include Platythyris cagillata, Concinnithyris cf. subundata, Ornatothyris sulcifera, Terebratulina etheridgei, Orblrhynchia parkinsoni and undeicribed examples of Cyclothyris, Kingena, Rectithyris and Boubelthyris. Bivalves are represented by Pycnodonte vesicularis, Aucellina coguandiana, Entolium orbiculare, small examples of Plicatula sp. , (in lower clay bed) and the inoceramids I. tenuis, I. concentricus, and I. anglicus. Other notable fossils occurring are columnals of lsocrlnus ? legeri, undescribed species of Hemiaster, and Nautilus, the corals Podoseris and Trochocyathus, the worm Rotularia umbonata, and fish teeth and vertebra.
It was from the Albian species of Inoceramus anglicus that Wood (1912) established the first scheme of phylogenetic evolution of Upper Cretaceous inocerames. Woods scheme was modified by A. Tsagareli (1942), and further advanced in studies by 0. Sietz (1956 1961 1962 1965 1967 & 1970), J. Sornay (1966), Kauffman(1970-79), Troger (1976), and others. Troger noted a change in the number of Upper Cretaceous inocerame species and sub species in the European, Westasiatic-North African Province, from one at the base of the Cenomanian, to thirty four in the Middle Coniacian, there after reducing to ten species in the upper part of the Coniacian, increasing again up to a maximum of thirty five in the Santonian, followed a steady decline in numbers. There is still much to be learned about the distribution and stratigraphical importance of inoceramids in the Northern Chalk Province. Over a period of many years, and during the course of the present work a large number of specimens have been collected stratigraphically, from the basal Albian Red Chalk up to the highest exposed beds of the chalk succession. Despite the generally poor state of preservation of this family of bivalves, their relative abundance at a number of levels throughout the Northern Chalk compared with other fossil groups, and the variation in shell morphology, provides one of the best means of biostratigraphic classification. The known horizons of inocerames found in situ are depicted in the appropriate figures and referred to in the relevant text's. A composite succession is shown in figures 3 & 16.
2.2 The Cenomanian
The base of the Cenomanian at Melton Bottoms (Fig. 4) is marked by a bed of ochreous coloured chalk, bored with Thalassinoides burrows and resting on the erosion surface of the underlying Red Chalk , marking the boundary between the Albian and Cenomanian Stages. The bivalve Aucellina coguandiana and the brachiopod Moutonithyris dutempleana extend up into this bed and the lower part of the overlying chalk where their range appears to be confined to about 1.5 metres above the base of the stage.
The grey gritty lower Inoceramus Bed which follows in sequence is full of fragmented shells and contains numerous casts of the inoceramid I. crippsii Mantell. In some specimens where the shell has been preserved, it is possible to identify examples which appear to be more closely related to Inoceramus schtindorfi Heinz, (J. Sornay 1980) which occurs in the French and German Cenomanian. Very large specimens of the terebratulids Ornatothyris and Rectithyris are fairly common, along with rarer examples of the gastropod Bathrotomaria perspectiva (Mantell). The echinoid Holaster subglobosus makes its first appearance in this bed with occasional species of Salenia which resemble S. petalifera (Goldfuss). Both these species along with B. persgectiva are present at a similar horizon in the lower pink beds at Speeton, including the rare occurrence of a Hemiaster sp. which exhibits a fairly broad petaloid ambulacra, almost like a Micraster, but the test has a rather bumpy appearance due to the inflated nodes on each side of the margin. This echinoid has also been found at South Ferriby at the same level. Although not described it is also thought to have affinities with Russian faunas. Body whorls of the spirally formed ammonite Hypoturrilites have also been found in this bed. A second overlying Inoceramus Bed is separated from the lower one by a sequence of thin marls (Jeans 1968-1973) and contains similar species in the basal part. The upper level weathers out in pale grey thin platy sections yielding flattened whorls of Schloenbachia sp., and occasional very rare complete specimens. Brachiopods also occur and are represented by species of Concinnithvris, Gibbithyris, Kingena, and Orbirhynchia.
The intervening beds of massive hard off white chalk up to the base of the dark grey bed (local equivalent of the Totternhoe Stone) are divided by a series of thin marls with several species of brachiopods occurring near or on the bedding planes. The lower Orbirhynchia Band of Jeans (1968) is present see (Fig.4) along with other species including Monticlarella jeffriesi, Orbirhynchia cf. mantelliana, Concinnithyris spp, Gibbithyris spp., undescribed Rhynchonellids and fragmented shells of Inoceramus sp. Also low and tall forms of CamerogaIerus cylindrica.
The Grey Bed or Totternhoe Stone rests on a well defined burrowed surface (C. J. Wood 1980), and including the overlying paler grey chalk, which grades down into it, varies in thickness from about 1 metre to 1.5 metres, and is impersistent in distribution. The lower part is a soft dark grey gritty chalk with many green coated pebbles, it has a very distinctive matrix which appears to be unique and confined to this horizon in the Northern Chalk. It is a highly fossiliferous deposit and contains a number of species. Of particular interest is the occurrence of the rare belemnite Actinocamax primus Arkhangelsky. Four specimens have been found by the author, since 1970, and appear to be the first record of this species in the Northern Cenomanian. Another rare much smaller belemnite Belenmocamax boweri Crick, was recorded in bed 3 at Rifle Butts Quarry near Market Weighton (Wright & Wright 1942). From the stated position in the top of the bed immediately below the Pink Band, it would place the horizon for this species about 1 metre above that of A. primus at Melton. Although B. boweri has not, as far as it is known, been found at Melton, it was recently discovered at South Ferriby, Rugby Portland Cement Quarry. The specimen was found in a loose block of chalk on a working platform about 6 metres below the Plenus Marls at a level approximating to the so called Gryphaea Band (Bower & Farmery 1910). The sand grade bioclastic chalk associated with this horizon and that of the belemnite appeared to be compatible, raising questions as to the range of this species, previously only recorded from a level lying some 3 metres below where the present specimen was found. Several species of bivalves are common in the lower dark grey chalk and include Plagistoma globosa, Limaria elongata, Lyropecten (Aequipecten) arlesiensis, Oxytoma sp., Pycnodonte vesiculare and Entolium orbIculare. Brachiopods are represented by large examples of usually squashed Concinnithyris sp., Terebratulina etheridgei, (Previously triangularis E.F. Owen 1988)and Grasirhychia martini, the serpulid Rotularia umbonata and varieties of other straight tubed worms are frequent, along with C. cyllndrica and H. subglobosus.
The overlying lighter grey bed consists of extremely tough gritty chalk with T. etheridgei and G. martini. Rare very large Holaster sp. are found at this horizon up to 68mm in length by 68mm wide and about 55mm in height, these undescribed forms are thought to have affinities with similar species found in the Cenomanian sequence in Russia. Large compressed specimens up to 60cm in diameter of the ammonite Parapuzosia (Austiniceras) austeni are fairly common in this bed, and are associated with poorly preserved, distorted casts of spirally coiled species of Turrilites, also present in the very top of the grey chalk immediately below the overlying pink beds, are occasional, inflated, ammonites which appear to relate to the finer ribbed Acanthoceras (Acanthoceras) rhotomagense (Brongniart), although identification is difficult due to poor preservation. The base of the Pink Band rests on the Grey Chalk, but the horizon is ill defined and impersistent. The upper part is predominately marly and weathers out into small cubes. The lowest bed has yielded a single specimen of Offaster or Echinocorys sphaerica Schluter, 72mm in length by 70cm wide and 62cm high, this species has not been observed below this level by the author. Jukes Browne (1877) suggested E. sphaerica was the link between Holaster and Echinocorys, A.G. Brighton (1928) assumed it to be an ancestor of Echinocorys, and Lambert (19O3 a) regarded it as a species of Echinocorys. More recently C.W. Wright (in conversation) considered E. sphaerica to be the ancestral stock from which all the Upper Cretaceous Chalk species Echinocorys was derived.
The occurrence of Echinocorys in most stages of the Northern Chalk (Mid Turonian to Campanian) will be described in the appropriate texts, and horizons depicted in the figures relating to the specimens found in situ. Although in the past this echinoid has been treated as a single variable species by some authors under the specific name of Echinocorys scutata, the wide variation in some test forms, a number of which have short ranges and are restricted to certain levels in the succession, proving to be excellent stratigraphic markers, has led to the adoption of a number of sub-specific names by numerous researchers. This species still has a very important role to be established in the biostratigraphic succession of the Upper Cretaceous Chalk and in conjunction with the inoceramids provides the best means of doing so. Other fossils to be found in the Lower Pink Band are mainly brachiopods, including abundant Concinnithyris concinna, rarer Kingena concinna, Terebratulina nodulosa, and occasional examples of Holaster subglobosus.
Above the Pink Band is a sequence of thinly bedded grey chalk about 1 metre thick, parted with a series of fine marls at 10cm intervals. This bed yields rare, very large specimens up to 30cm in diameter of Acanthoceras rhotomagense jukesbrownei Spath. Small examples of Orbirhynchia wiesti also occur along with Inoc. sp. ?conicus. A further prominent marker bed of pale grey chalk with a thin marly base occupies a position about 2.5 metres higher in the succession, named the Gryghaea Band, in Bower & Farmery's section (1910), on account of the large numbers of the small oyster Pycnodonte vesicularis found in the basal marl. The uppermost part of this bed marks the highest linit of Holaster subglobosus and is taken as the top of H. subglobosus Zone (C.J. Wood 1980)
The remainder of the overlying chalk up to the Plenus Marls at Melton does not include the Upper Pink Band of Bower & Farmery (1910) in fact there appears to be no records of this horizon North of the Humber and would seem to be confined to the Lincolnshire succession. The uppermost 4 metres of the sequence below the P. Marls is assigned to the Holaster trecensis Zone, the major part being made up of massive off white chalk with marly bedding planes, with the lower part yielding a few terebratlids, mainly Ornatothyris sulcifera and species of Gibbithyris, along with the serpulid Rotularia umbonata and several other varieties. Inoceramus pictus is fairly common, and large examples of a Nautilus sp. also occur as does squashed specimens of the zonal fossil Holaster trecensis. Other echinoids with a tall test form are present and have been referred to Echinocorys sphaerica by some authors, but they are thin tested and usually crushed or distorted making identification doubtful. The top bed of this section includes the burrowed erosion surface, equivalent to the Sub Plenus Marls of the Southern Chalk (Jefferies 1963), the extremely hard cream coloured chalk appears to be the local variation of the Upper Pink Band in Lincolnshire, and contains numerous examples of H. trecensis, varieties of Discoidea cylindricus, and occasional nests of well preserved specimens of Ornatothyris sulcifera.
A conglomerate bed rests on the burrowed surface of the top bed and the belemnite Actinocamax plenus has been found by the author at Melton, and S. Ferriby in the khaki marl (Basal part of P. Marl complex), which overlies the conglomerate. A number of fossils have been recovered from this horizon, including the brachiopods Ornatothyris sp, and Orbirhynchia multicostata. Wood (1980) gives additional species I wiesti, and Monticlarella jefferiesi an assemblage characterizing high levels within the Plenus Marls. These latter two species have not been found in the Northern Chalk at this level by the present author.
The erosion surface below the Plenus Marls (Black Band) is taken as the top of the H. trecensis Zone, it also marks the base of both the Welton Formation and the Sciponoceras gracile Zone (Wood & Smith 1978). The latter takes in the P. Marls and the basal beds of the Welton Formation up to the thin marls just below the first Inoceramus bed, this horizon also coincides with the top of the Cenomanian Stage (Rawson et al. 1978) see (Fig4.) This marly complex has been adequately described by Jefferies, and others, it is therefore not intended to add further, other than to mention the exposures which can presently be seen at S. Ferriby, Elsham, Nettleton, and Bigby in N. Lincolnshire, where the average thickness is 50 to 60cm, and on the North Bank at Melton and Bishop Wilton, 60 to 70cm. This series of khaki marls embracing two prominent dark bands are almost without any fossils, although rare brachiopods, and fish scales have been recorded, are thought to have been deposited in near stagnant bottom conditions (Wood 1980)
3. THE WELTON FORMATION
The huge quarry at Welton Wood (Fig. 5) lying in sequence just above the Melton Bottoms section, the selected stratotype of Wood & Smith (1978), is the largest chalk excavation North of the Humber with a working face in excess of 800 metres. The basal beds of the formation including the Plenus Marls underlie the floor of the exposure and are best seen in the car park area of the main works.
The base of the formation is drawn at the top of the H. trecensis Zone (Cenomanian) and therefore includes the S. gracile Zone. The overlying Mytiloides labiatus and Terebratulina lata Zones follow in stratigraphic sequence (Figs. 5 & 6) with the upper boundary of the succession taken just below the Ravendale Flint giving an overall total thickness of about 54 metres.
The Welton Formation embraces the highest beds in the Cenomanian, and the lower and middle parts of the Turonian stage, terminating at the top of the T. lata Zone. The main part consists of hard massive bedded flinty chalk with sparse fossils other than inoceramids. The lower 5 to 6 metres being without flints, with thinner bedding, and containing several gritty shell bands with numerous inoceramids, brachiopods, and small echinoids. In the upper few metres of the formation the massive bedding forming the bulk of the succession is replaced by more thinly bedded chalk coinciding with an influx of echinoids, brachiopods, and large inoceramids.
3.1 Sciponoceras gracile Zone
The basal Sciponoceras gracile Zone including the P. Marls complex is about 1.6 metres thick at Welton and at Bishop Wilton some 28km due north. Further south across the Humber on the South Bank at Elsham the sequence extends up to 2.8m. The upper boundary is taken at about 0.5m below the first band of Mytiloides labiatus marked by a chalky marl up to 5cm thick. The lower beds of the zone above the P. Marls contain terebratulids, broken shells of inoceramids, possibly I. pictus sp.and Turnus sp.
3.2 Mytiloides Labiatus Zone
The succeeding biostratigraphic zone is marked by the entry of floods of the zonal fossil indices Mytiloides labiatus. The chalk is fairly hard, and flintless, exhibiting some thin, gritty, and shelly bedding sequences, some which are made up entirely of inoceramid shells, providing useful marker horizons. The upper beds yield variants of M. labiatus. Single examples of the Ammonite Mammites nodosoides (Schluter) have been found by the author in the lower beds of the zone at both Welton and Elsham, along with two very large specimens (60cm) of Parapuzosia (Austiniceras) austeni (Sharpe), recovered from the M. labiatus shell beds overlying the Cenomanian at Melton Bottoms. These beds also yield numerous small specimens of the echinoid Conulus subrotundus, a species traced in bands at Hessle, South Cave, and Burdale at a similar level. (Wright & Wright 1942). Other echinoids include Hemiaster nastulus and a single example of Conulus castanea. Brachiopods are represented by varieties of Gibbithyris, Concinnithyris, and Orbirhynchia cuvieri. The upper boundary of the zone occurs some 30cm below the first main flint course (Wood 1980) giving an overall thickness of about 4m. for the sequence at Welton.
3.3 Terebratulina Lata Zone
From a line just below the occurrence of the first main flint, the Terebratulina lata Zone extends upwards about 48m. The whole of the zone is represented at Welton including the upper boundary marker, the Ravendale Flint, and the main part of the succession consists of massive bedded hard chalk with courses of nodular and burrow filled flints. Other prominent marker flints named in Wood & Smith (1978) are the Ferruginous Flint (known by quarry men as the Red Bed), and the Deepdale Flint named from the Lincolnshire sequence.
A number of marl bands are present in the sequence and the names applied by the previous authors are adopted in the present paper to avoid confusion, although most of the named horizons apply to Lincolnshire locations. (Figs. 5 & 6).
Nearly all these marls and flint markers are traceable in a number of exposures north of the Humber, and some can be identified on the Northern Edge of the Province at Gt. and Little Thornwick Bays, also at N. Landing, where the deposits are much thicker and more associated with the Cleveland Basin.
In the lowest, part of the zone slightly larger, more inflated examples of Conulus occur on bedding planes along with thick shelled species of terebratulids related to Gibbyrthyris, and more common inocerames of the I. lamarcki/brongniarti group.
Most of the remainder of the massive chalk succession is divided by named marls and flints (Figs. 5 & 6) and is poorly fossiliferous. (Known as the Barren Zone by many earlier workers). Amongst the few species occurring, I. brogniarti and I. lamarcki are to be found, mostly on marly bedding planes. Occasional crushing teeth of Ptychodus may be recovered from beds below the Ferruginous Flint at both Welton and South Cave, they have also been recorded from the Hessle pits in the past. The zonal index fossil T. lata although not common in the main mass of the chalk, does occur in bands at specific horizons, often preserved as a ferruginous pseudomorph, well preserved specimens are present in the highest beds.
Towards the top of the zone the massive chalk is replaced by thinner bedding sequences coinciding with an influx of a much more diverse fauna, with the early changes beginning to take place just below the thick grey/brown (4 to 6cm) Deepdale Lower Marl (Fig. 6a) where the chalk contains large specimens of I. cuvieri / I. lamarcki group. The zonal work carried out by Rowe (1929) in Lincolnshire, listed many exposures, and a detailed analysis of his recorded inoceramids appears to show that I. brogniarti was the dominant species in the main part of the T. lata Zone and the incoming of I. cuvieri taking place towards the junction and extending up into the overlying Sternotaxis planus Zone. A similar distribution pattern would seem to be evident on the North Bank of the Humber at Welton, and at Newbald Wood (Fig. 6 & 6a) where large inoceramids of the I. cuvieri group occur below the Deep dale Lower Marl some 5»5m below the suggested upper boundary of the T. lata Zone. This same horizon is also said to mark the level at which the lowest species of the German echinoid Infulaster excentricus Woodward has been recorded, (Smart & Wood 1976) in the Lincolnshire succession. As far as it is known there are no records of this species being found below the Deepdale Marls in chalk North of the River Humber.
Other marker horizons characterising the upper k to 5« of the zone include the Upper Deepdale and Beacon Hill Marls. At Newbald Wood the latter marl is represented by a marly bedding plane, the intervening beds between these two marls yielding the rhynchonellid Grbirhynchia reedensis. Above the Beacon Hill Marl and about, 5m below the Ravendale Flint a 0.3m bed of very hard nodular chalk occurs with some nodules encased in a thin hard coating of tenacious marl, this horizon is the source of common species of I. excentricus, mostly water worn and eroded, some encrusted with serpulids, suggestive of a pause in deposition. Amongst the specimens are variants of acute and depressed forms, some authors claiming depressed ones occur only in the top of the T. Lata Zone with acute forms characterising the S. planus Zone. On present evidence it would appear there is a trend towards some higher tested forms occurring in both the S. planus and lower part of the M. cortest. Zones, but high and low profile specimens occur at both the lower and upper extent of the range of this species.
A single almost complete test of Micraster ? michelini has been found in the thinly layered chalk above the nodule bed in association with two examples of the earliest species of primitive Echinocorys, Stereocidaris serrifera, and a number of specimens of Sternotaxis planus. The lowest recorded by the author presumably the same horizon and source of common H. planus in the upper part of Welton Quarry referred to by Wright & Wright (1942. Pit no 8). In the same bed a band of large I. cuvieri and other unidentified I. sp. occurs in association with an influx of a diverse fauna of brachiopods, including Concinnithyrris, Gibbithyris, Kingena elegans, Orbirhynchia cuvieri, O. reedensis and an undescribed variant with coarse deeply incised costae.
The transition from massive bedded chalk below the Deepdale Marls to more thinner layered sequences above, and the incoming changes in the fauna taking place below the Ravendale Flint which lies just above the hard nodular erosion surface, would suggest a suitable boundary to be drawn for the top of the T. lata Zone and the base of the S. planus Zone, coinciding with the Welton/Burnham Formation junction of Wood & Smith (1978) at the bedding plane below the Ravendale Flint, a level which is also marked by the commencement of tabular and semi tabular flints characteristic of the overlying Burnham Formation.
THE BURNHAM FORMATION
In this account the Burnham Formation is erected entirely from exposures North of the Humber, forming a continuous succession apart from a gap in the upper part above the Middleton Marl. The previous work of Wood & Smith (1978) comprised of sequences occurring on both sides of the Humber, and at that time was incomplete due to the lack of suitable exposures in both the Micraster cortest. Zone and the upper part of the flinty Lower Hagenowia rostrata Zone. The latter zone is still not fully exposed.
The formation is made up from exposures at eight locations and assembled in the following ascending order, Newbald Wood (Fig. 6a), Kilnwick Percy (Fig. 6b), Enthorpe (Fig. 8), Willerby (Fig. 9), Little Weighton (Fig. 10), Eppleworth (Fig. 11), Middleton (Fig. 12), and Langtoft (Fig. 13) It is possible to trace the major marker horizons including those nominated for the Lincolnshire succession throughout the region.
The biostratigraphical zones within the formation include the Sternotaxis planus Zone (Upper Turonian), the Micraster cortest. Zone (Coniacian), and the proposed flinty Lower Hagenowia rostrata Zone (Coniacian), (Division defined in the Stratigraphical Sequence T. p.). Within the succession considerable lithological changes take place from the hard massively bedded chalks of the Welton Formation to more thinly deposited, softer chalk sequences, interspaced with marls and fine marl seams, along with many tabular, and semi tabular flints, with examples of twinning flints occurring frequently in parts of the M. cortest. and Lower H. rostrata Zones. The approximate thickness for the formation extending from the Ravendale Flint up to the highest true flint at High Stacks including borehole evidence for the unexposed upper part is given at 138 to 140 metres.
4.1 Sternotaxis Planus Zone
The small pit at Newbald Wood 2.5km east of N. Newbald forms an important bridging link between the Welton and Kilnwick Percy sequences. The exposure includes the Deepdale Marls, the Beacon Hill Marl horizon, Ravendale Flint, and a broken, disturbed, section of the Triple Tabular Flints at the top. This pit is now one of the few locations North of the Humber, apart from the Flamborough area, where the Burnham Formation basal boundary can still be observed at the present time. The fauna has been described in the previous text and reference made to the influx of some early echinoid species just below the base of the S. planus Zone and to what appears to be the lowest record of primitive Echinocoryrs sp. with a fairly retracted base, 68mm long, 64mm wide, and 50mm high with a pointed apex, the maximum width about half way up the test height. The closest parental stock from which this species may have been derived is the echinoid Echinocorys (Offaster) sphaerica occurring in the upper part of the Cenomanian. As far as it is known there are no records of any other linking forms from the Lower Turonian in the north. The distribution of Echinocoryrs above the T. lata Zone is widespread throughout the chalk succession, and at a number of levels is the most common echinoid. The variation in size and shape of some forms, confined to specific horizons are of considerable stratigraphic value, the real importance of this role in the Northern Province has still to be worked out.
The sequence at Newbald (Fig. 6a) is continuous up into the base of the now disused larger quarry near Warrendale Farm, Kilnwick Percy (Fig. 6b) where the two upper flints of the Triple Tabulars were formerly exposed at the bottom of the working face, now covered in talus. The Ulceby Marl and Oyster Bed are present at the top of the exposure, extending upwards the S. planus approx 19 metres.
The chalk in this part of the succession is still hard and inclined to be nodular at some levels in the lower part with a general transition to softer chalks higher up. The facies exhibits a number of major marker horizons established for the Lincolnshire sequence by Wood & Smith (1978), one of the most important of these being the N. Ormsby Marl, seen about 0.75m above the Triple Tabular Flints at this location. Called the Ferruginous Marl by Rowe (1929) the thickness varies from 6cm. extending up to 11cm. at some localities, and is traceable over a wide area in Yorkshire, Lincolnshire, and North Norfolk.
A series of thinly bedded chalks overlie the N. Ormsby Marl and contain a further flood of small brachiopods, mostly species of Concinnithjrris, Gibbithyris, rarer Kingena elegans and common Orbirhynchia sp. A massive pale grey tabular flint occurs about 1m. above the marl, named the Ludborough Flint by previous authors and designated the White Flint by Rowe (1929). At Kilnwick Percy the flint thickness is variable between 25cm. and 35cm and is also regarded as a prominent and continuous marker level throughout the region. A specimen of the loosely coiled ammonite Hyphantoceras reussianum (Orbigny) is recorded by the author some 1.5m. above the flint horizon.
Other notable marls in the lower part of the quarry are the Thornton Curtis, and successive Wootton Marls. A large paramoudra flint is present in situ just below former marl, the remainder of the succession comprising a series of thin and thick bedded chalks interspaced with lenticular, nodular, and semi tabular flints, some being markedly carious. Occurring within the chalk beds are sporadic examples of mostly crushed Sternotaxis planus along with fragmented shells of Inoceramus sp., and occasional poorly preserved specimens of thin tested Echinocorys sp. Towards the top of the exposure a band of echinoids occurs about 1m below the Ulceby Marl, species include small rounded, and larger ovate varieties of Echinocorys sp., Micraster sp., and Sternotaxis planus. All the specimens found at this horizon were in poor condition, giving rise to problems of identification. Fragments of large Pachydiscid type ammonites are recorded about 1.5m below the marl here, and a complete specimen 35cm in diameter was observed by the author at a similar level in the Vale House Quarry Ulceby Lines. The echinoid band is also present there at a correlating horizon with Kilnwick.
The Ulceby Marl is a distinctive partly chalky marl containing small crinoid columnals, maintaining an average thickness of about 4cm. proving to be an excellent marker horizon traceable over a wide area north and south of the Humber. A 20cm. thick band of the oyster Pycnodonte vesicularis occupies a position about 2.5m. above the marl and also occurs throughout the region. These two important markers lie close to the top of the sequence at Kilnwick and are capped by a double band of thick nodular flints. (Fig. 6a) The upper beds observed at the previous locality form the base of the continuing succession at Enthorpe Railway Cutting (Fig. 8) where the main exposure to which this section refers, commences at the bridge close to Enthorpe House (formerly Enthorpe Railway Station) which carries the road over the now disused rail track. From this point the cutting extends in a south westerly direction for about 0.75km. and is cut through a chalk outcrop exhibiting several minor faults, dipping to the west, and exposing a continuous sequence of beds from just below the Ulceby Marl (S. planus Zone) at the western extremity of the cutting up to levels equating to the lower middle Micraster cortest. Zone at the eastern end near to Enthorpe House, extending the succession upward by about 30 metres. Although now becoming overgrown with a high build up of talus, this section remains the best exposure of the S. planus/M. cortest. zonal boundaries in the Northern Chalk and should be preserved for future research.
Recent fieldwork by the author at the western end of the cutting succeeded in excavating and exposing the Ulceby Marl for the first time, which at this locality lies almost 3m. below the U. Oyster Bed (Fig. 8). Above the marl, lines of double spaced nodular flints occur and continue upwards for almost 7m. The 20cm. thick U. Oyster Bed seen at the top of the previous exposure consists of a soft, fine marly chalk with abundant Pycnodonte vesicularis of large size compared with other examples from the Northern Chalk. Brachiopods including Orbirhynchia sp. and rare ?Cretirhynchia sp. occur along with crushed species of Gibbithyris, Spondylus, Limaria, and fragmented shells of Inoceramus sp. Occasional distorted examples of S. planus are present in close proximity to the oyster band. The distinctive flint lined beds above this level yield large well preserved specimens of Gibbithyris semiglobosa and sporadic occurrences of S. planus, there is also a tendency for some of the flints to become very nodular in this part of the Zone.
At a point some 7.2m.
[This version of the text ends here]
[Scanned and edited August 2010 by Mike Horne.]
[Editor’s note – Felix originally submitted the paper to the editors of the Proceedings of the Yorkshire Geological Society in a form like this. The editors asked him to split it into two papers – one for the Flamborough Formation and one for the lower formations. A referee asked Felix to split the lithostratigraphy and biostratigraphy into different sections in the papers. Felix was upset about this but complied.]
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