Humberside Geologist no. 15

In North Lincolnshire, several of the sites quoted as type sections for recently updated stratigraphical nomenclature have now been filled in. A former landfill site just south of Ulceby has been excavated in the Turonian chalk of the Burnham Chalk Formation (Sternotaxis plana zone). The author was provided with an opportunity to log the section in detail. A lithostratigraphic record is presented which describes beds not previously exposed at this locality and introduces proposed new nomenclature, the Vale House Flints and the Main Carious Flint.

A section of the Burnham Chalk Formation at Vale House Quarry, Ulceby was described by Wood and Smith (1978) in their paper on the lithostratigraphical classification of the Chalk of the Northern Province. It ranged from just above the Wootton Marls up to the Enthorpe Marls and was their type locality for the Ulceby Marl and Ulceby Oyster Bed. This quarry has since been back-filled, at least in part, and until recently much of the section described by Wood and Smith was lost. Ulceby Vale Quarry (TA 104133) is on an adjacent site (Figure 1) and was visited by the author in October 1996 when it was operated by the Clugston Group, Scunthorpe. The floor of the quarry was then at the level of the Ulceby Marl.

Figure 1. Location of Ulceby Vale Quarry.

J.E. Churchill Ltd. of Kirton Lindsey acquired the quarry in 1998 and have recently been extracting chalk for use in construction of nearby port facilities. The quarry has been deepened to reveal the beds below the Ulceby Marl. Recent visits by the author, including field meetings of Hull Geological Society on July 18^th 1999 and Leeds Geological Association on May 21^st 2000, noted the rapid changes taking place at the site. The author revisited the quarry on several occasions during 1999 and 2000 when detailed logging of the section was possible and when deepening had reached its probable final level. A section at the top of the quarry was newly excavated during Spring 2000.

A composite lithostratigraphic record of the section currently visible and accessible is shown in Figure 2. The exposure occurs in the Sternotaxis plana zone of the Burnham Chalk Formation (Turonian). Sections of the zone fossil were observed at several levels although only one three-dimensional specimen was collected, from an erosion surface about 70cm below the Ulceby Marl.

Figure 2. Lithostratigraphic log of Ulceby Vale Quarry.

Three contrasting groups of beds can be recognised in the section, a lower marl-rich group containing the Wootton, Thornton Curtis and North Ormsby Marl bands, a flint-dominant middle group characterised by several carious flint levels and an upper flint-marl-oyster bed succession containing the Ulceby Marl and Oyster Bed. The thickness of the full section is just over 20m.

The bottom 6m of the Ulceby Vale section is dominated by chalk containing four persistent marl bands and two distinct flint levels. A 16cm thick tabular flint occurs above 30cm of chalk at the bottom of the deepest part of the quarry. This is the top Triple Tabular Flint and is overlain by chalk which is noticeably fine grained and has a porcellanous texture. The author has recorded 45cm of chalk with similar texture above the topmost of three tabular flints taken to be the Triple Tabular Flints at a small exposure in Irby Dale (TA 195055).

The thick (11cm) North Ormsby Marl is very well exposed. It is greenish grey in colour and contains bright ochreous ‘pellets’ especially at the base. Weathering gives the marl a rusty appearance and this is undoubtedly why Rowe (1904) named it the ‘Ferruginous Marl’. Sponge spicules and thin tested foraminifera were recovered from washed and sieved samples of the marl. The top of the North Ormsby Marl grades into 20cm of laminated chalk and marl above which white chalk predominates. Orbirhynchia sp. and ferruginous traces of sponges occur in chalk with a slightly silty texture, quite different from that described from below the North Ormsby Marl.

A band of very pale grey flint occurs 1.3m above the North Ormsby Marl. The total thickness of the flint band is up to 30cm, but here it is a double flint with 5 to 7cm of chalk between layers. This is the Ludborough Flint which, because of its distinctive paleness, Rowe (1904) referred to as the ‘White Flint’.

About 1.8m of chalk containing minor marl and flint bands occur above the Ludborough Flint. The chalk is generally laminated with ferruginous wisps and occasionally consists of nodules of chalk with envelopes of marl. The pale grey lenticular flints which occur 45cm below the overlying Thornton Curtis Marl show planar tops with rounded lower surfaces.

The Thornton Curtis Marl is a brown, sticky marl up to 2cm thick and is succeeded by white chalk with two minor semi-tabular flint levels. The lower of the two Wootton Marls was recorded at 1.35m above the Thornton Curtis Marl, just above increasingly marly chalk beds. It is dark grey in colour, 1cm thick but commonly splits to form a double band, or more locally a marl complex, up to 2cm thick. White chalk containing a thin line of discrete, nodular flints associated with marl beneath separates the two Wootton Marls. The upper Wootton Marl is about 40cm above the lower one and is also dark grey in colour, laminated and up to 2cm thick.

2.2. Middle Flint-dominant group = Vale House Flints (new name)

A new name, the Vale House Flints, additional to the established names of Wood and Smith (1978), is proposed for the interval between the first semi-tabular flint above the Wootton Marls and an erosion surface about 70cm below the Ulceby Marl. A detailed analysis of the flints is shown in the appendix. Fifteen distinct bands of flint have been recognised in 6.4m of white and greyish white chalk. The flint bands within this group are indicated with Roman numerals I to XV in Figure 2. Whitham (1991, Fig.6) records eleven flint levels between the upper Wootton Marl and the Ulceby Marl at Warrendale Quarry, Kilnwick Percy situated on the western outcrop of the Yorkshire Wolds. This section seems to expand eastwards, where up to 9m is recorded at North Landing, Flamborough (Whitham 1991, Fig. 7).

Tabular and semi-tabular flint bands dominate the section separating the Wootton Marls and the Ulceby Marl. Although marl is common, it occurs as wisps, sutures and in laminated chalk beds but is nowhere sufficiently strong to form a continuous seam. Fossils are commonly observed but preservation is poor and collectable specimens are therefore rare. Simple calculations using mean thicknesses of flint bands would suggest that this interval has a flint content of about 35%.

There is a distinct shell-rich level above band III, a semi-tabular to lenticular flint, where ‘rafts’ or plates of Inoceramus sp. up to 1m in length have been recognised. These are often overlapping, producing in places a thickness of 15cm. Wood (in Gaunt, Fletcher and Wood 1992) has suggested that these may be of a form close to Inoceramus lamarcki stuemckei Heinz. Sections of Sternotaxis plana (Mantell) were also recorded at this level together with ferruginous moulds of a small brachiopod not unlike the preservation of Terebratulina lata (R. Etheridge) recorded by many authors in beds of the Welton Chalk Formation.

A localised semi-tabular, occasionally nodular flint occurs between bands IV and V. Because of its lack of reliable continuity around the quarry it has been allocated the position 4a and is not included as one of the fifteen ‘main’ bands. Band V is the thickest flint in the group, a massive tabular band which is also distinctly carious and, as noted in Figure 2, specifically identified as the Main Carious Flint (new name).

A pale blue mineral is occasionally seen on fracture surfaces of otherwise grey flints. Band VI is the lowest flint within which this colouration was noticed but it also occurs in flints of bands VIII and IX. A marl complex up to 10cm thick occurs between bands VII and VIII above which the chalk becomes yellowish and slightly silty textured. Iron-staining is present in the flints of band VIII which also has an irregular base suggesting possible burrow-fill origins.

Above band XI the chalk becomes nodular with rounded surfaces picked out by enveloping dark grey marl. One poorly preserved specimen of S. plana was observed at this level. Sections of other possible S. plana occur above bands XII and XIV. The interval between bands XII and XIII contains yellowish chalk in which ferruginous outlines of sponges and S. plana can be recognised. Rafts of Inoceramus sp. also occur at this level and locally have been incorporated into the flint of band XII.

Bands XIV and XV are normally about 75cm apart but in two or three places in the quarry can be seen to ‘link’ vertically via massive paramoudra flint structures. Band XIV, 20-25cm thick has a relatively planar base but its top surface is often rounded or even tubular. Band 15 on the other hand has a rounded, low amplitude undersurface with a planar top. A very well preserved Orbirhynchia sp. was collected from 30cm below the base of band XV.

There are 92cm of pinkish or orange-tinted chalk occurring above the base including a thin, impersistent marl. The author recorded a surface associated with many stylolites which revealed a reasonably good specimen of S. plana. This level is some 70cm below the Ulceby Marl. Whitham (1991) recorded an echinoid band about 1m below the Ulceby Marl from Kilnwick Percy, East Yorkshire. This ‘stylolite surface’ is tentatively correlated with Whitham’s band of echinoids.

The topmost beds can be reliably logged for about 6m above this level before weathering or difficulty of access causes problems. Directly below the Ulceby Marl the still pinkish chalk contains ferruginous markings tentatively attributed to sponges.

The Ulceby Marl is a very conspicuous and therefore important marker band. It is dark brown in colour, 2 to 4cm thick and has a rather gritty texture, the latter due to a concentration of echinoid spines and crinoid columnals. White chalk, occasionally orange-stained, succeeds the Ulceby Marl. It contains rare outlines of S. plana and taller ?Echinocorys sp. with rare isolated nodular flints. A partly desilicified or carious semitabular flint (8 to 15cm thick) occurs 65cm above the Ulceby Marl and marks the base of a 2m flinty chalk unit separating the Ulceby Marl from the Ulceby Oyster Bed. A very thin marl marks the top of the flinty unit. Fragments of a large bivalve (?Inoceramus sp.) showing evidence of a large, rather smooth shell with widely spaced, distinct but not pronounced growth lines and no radial ornament were collected from 18cm below the marl. Wood (in Gaunt et al 1992) has described Inoceramus modestus Heinz from a similar level.

28cm of chalk occurs above this very thin marl band, the top 12cm of which is rich in oysters, Pycnodonte vesicularis (Lamarck), and can be traced successfully around the quarry wherever accessibility allows. This is the Ulceby Oyster Bed recognised and named by Wood and Smith (1978). Weathered sections often provide good collecting ground for specimens of brachiopods including common Gibbithyris subrotunda (J. Sowerby), Cretirhynchia ?minor Pettitt and Cyclothyris sp.

A return to flinty chalk is recognised in beds above the Ulceby Oyster Bed. There are nodular and semitabular levels in hard white chalk. Inoceramid fragments are quite common and there are one or two thin but rather insignificant marls.

A comparison of thicknesses between distinctive marker beds recorded by Whitham (1991; Figure 6) at Kilnwick Percy, East Yorkshire and by Wood (1992; Figure 34) from a standard composite succession is shown in Figure 3. The figures attributed to Whitham and Wood are calculated from the diagrams quoted.

Figure 3. Comparison of thicknesses (m) between marker beds within the Burnham Chalk.

There is close agreement between the figures presented by Wood (1992) as a standard composite section for the Kingston-upon-Hull and Brigg area and those of the Ulceby Vale section. The figures for the Kilnwick Percy section, north of the Humber, differ significantly from Ulceby Vale only in the thickness of the interval occupied by the Vale House Flints, i.e. that between the Wootton Marls and the Ulceby Marl. A relative thickening of this interval in North Lincolnshire is suggested and is further intimated by comparing a composite succession from north of the Humber with that of borehole evidence in South Humberside (now North Lincolnshire) (Whitham 1991; Figure 14).

Ulceby Vale Quarry represents a significant section in the Burnham Chalk succession. It is clear and mostly accessible and the exposure of the two Wootton Marls and the Thornton Curtis Marl is particularly interesting; neither has previously been described from this locality and their type sections (Wootton Manor Pit and Thornton Curtis Pit respectively) have been completely back-filled in recent years.

Acknowledgments. I would like to thank Mr. Eric Sandal (Clugston Group) for his cooperation in 1996 when I first visited Ulceby Vale Quarry and particularly for arranging a ‘scraping’ of the quarry floor to allow me my first good view of the Ulceby Marl.

Mr. C.J. Wood identified my first collection of fauna from the Ulceby Oyster Bed (1996) and accompanied me on my first revisit in May 1999 offering advice and guidance.

Information about the recent workings of the quarry and the destination and use of materials extracted was supplied by Mr. Eddie Wainwright (formerly of J.E. Churchill Ltd.) who also facilitated access to the site. Mr. Charles Salmon (Managing Director, J.E. Churchill Ltd.) has supported my work on the Chalk by permitting access to Ulceby and other sites in North Lincolnshire and for this I am very grateful. Mr. Brian Beechey (Quarry Supervisor, Ulceby Vale) provided advice on safety whilst on site and showed a cheerful interest in the author’s work.

Rowe, A.W. 1904. The Zones of the White Chalk of the English Coast. 4 Yorkshire. Proceedings of the Geologists Association. 20, 193-296.

Whitham, F. 1991. The Stratigraphy of the Upper Cretaceous Ferriby, Welton and Burnham formations north of the Humber, north east England. Proceedings of the Yorkshire Geological. Society, 48, 227-254.

Wood, C.J. and Smith, E.G. 1978. Lithostratigraphical classification of the Chalk in North Yorkshire, Humberside and Lincolnshire. Proceedings of the Yorkshire Geological. Society. 42, 263-287.

Wood, C.J. 1992. Cretaceous. Chapter 5, pp 71-101 of Gaunt G.D., Fletcher T.J., and Wood, C.J. 1992. Geology of the country around Kingston upon Hull and Brigg. HMSO London, for Geological Survey of Great. Britain. ix + 172pp. 6pl.

A brief visit to Ulceby Vale on 7^th December 2005 found the quarry abandoned but the floor had drained to reveal all three of the Triple Tabular Flints in a ‘sump pit’. The final working floor level appears to have been taken at the North Ormsby Marl.

Author’s address:-

P.N. Hildreth, Kimberley, Bigby Road, Brigg, North Lincolnshire, DN20 8BU.

Key to Flint Types: T = tabular; ST = semi-tabular; L = lenticular; N = nodular/burrow