THE GEOLOGY OF THE RUGBY PORTLAND CEMENT CO. MIDDLEGATE QUARRY AT SOUTH FERRIBY.

SHEET NO. 106, GRID REF. SE 992204.

BY F. WHITHAM

The magnificent quarry at South Ferriby, owned and operated by the Rugby Portland Cement Co. has been visited on a number of occasions over the last 25 years, and as a result it has been possible to observe and record the biostratigraphy as quarrying progressed, widening and deepening the workings.

By the year 1968 the base of the Cenomanian Chalk had been reached and the beds of Red Chalk, Carstone, and Jurassic Clays exposed. The Red Chalk and Carstone were unsuitable for cement making and were subsequently utilized as backfill. The Upper Jurassic Clays (Ampthill and Kimmeridge) occurring below the Carstone proved to be ideal in the cement manufacturing process and have now been excavated to a depth of approximately 21 metres. Rapid and ever changing quarrying operations make it difficult to predict the accessibility of exposures when visiting the quarry. The quarried chalk and clay is moved to the main works by conveyer belt over a distance of 1.75 kilometres.

The Ampthill Clay seen in the base of the quarry (R. pseudocordata Zone 13 metres thick) forms the highest beds of the Upper Oxfordian Stage and grades up into the overlying Lower Kimmeridge Clay. The junction between the two stages is taken at the Oxytoma Cementstone (see log). This is the only exposure in the U.K. where the Oxfordian/Kimmeridgian boundary can be observed at the present time.

On the North Bank at Melton Bottoms Quarry (SE 970270) the Kimmeridge Clay and the Ringsteadia pseudocordata Zone of the Ampthill Clay are absent reflecting the northerly attenuation of these beds, brought about by the effects of the Market Weighton Block. Lower zones in the Ampthill Clay at this location yield ammonites and belemnites, also large Gryphaea dilatata which do not occur at South Ferriby and the exposed 15-16 metres of clays are representative of the Decipia decipiens, Perisphinctes cautisnigrae and Gregoryceras transversarium Zones, yielding examples of Decipia, large perisphinctids, Amoeboceras and Cardioceras. The overall exposures of the Ampthill Clay beds in the Humber area at the two localities appears to exceed 45 metres (147 ft).

Body chambers of the Upper Oxfordian ammonite Ringsteadia are characteristic of the main part of the 13 metres of Ampthill Clay at South Ferriby, the lowest 2 metres or so visible beneath the large septarian lenticles near the base of the section may belong to the underlying zone. The lowest 4 metres of the succeeding Kimmeridge Clay belongs to the Pictonia baylei Zone and large well preserved zonal species occur in fossiliferous nodules in the lower part of the zone. The boundary between this and the overlying Rasenia cymodoce Zone is taken at the highest and most prominent of three siltstone bands between 3 and 4 metres from the top of the clays. The zonal ammonite is common in hard silty clays in this part of the sequence along with numerous bivalves including Thracia depressa, Deltoideum delta, Oxytoma expansum, Camptonectes sp. and small oysters. These species range through the whole of the clays and occur as shell beds at several horizons.

The Carstone at South Ferriby is about one metre thick consisting of coarse grained friable sandrock with limonite ooliths and many polished pebbles, the sand weathering yellow and becoming red at the top before grading into the overlying Hunstanton Red Chalk. The brachiopods Burrirhynchia leightonensis and Cyclothyris mirabilis occur in the highest 20 cm of the Carstone (comparable with the Shenley limestone, Leymeriella regularis/L. tardefurcata Lower Albian Zones at Leighton Buzzard.

Parts of the Middle and Upper Albian substages are represented within the overlying Red Chalk confirmed by the discovery of the ammonites Dimorphoplites cf. hilli and Anahoplites planus in the basal red clays and Mortoniceras (M) - in the higher pink beds. The Red Chalk is highly fossiliferous, yielding many belemnites; Neohibolites minimus and attenuatus, several species of brachiopods dominated by Moutonithyris dutempleana and bivalves including inoceramids.

The overlying Cenomanian chalk (Ferriby Formation) although appearing to be lithologically monotonous, exhibits several important marker horizons including the hard grey gritty Totternhoe Stone bed with very large ammonites (Austiniceras austeni) brachiopods, echinoids, bivalves and fish teeth. The Lower Pink Band also yields a similar fauna. Higher in the sequence a dark grey marly bed the Nettleton Stone packed with the small oyster Pycnodonte vesicularis, marks the upper limit of Holaster subglobosus the zonal index species. The Nettleton Stone can also be compared with a similar horizon in the Cenomanian succession at Rheine, West Germany. The upper 6 metres above the stone band is assigned to the Holaster trecensis Zone with the common occurrence of this echinoid at several horizons. The overlying Black Band (thick marl ? volcanic/anoxic event) is exposed at a number of localities both north and south of the Humber and also represented by a thick unit (up to 2 m) of varegated marls near Hannover closely relating the continuity of the English/German Cenomanian/Turonian succession (Smart & Wood 1976). The faunal succession is indicated on the attached log of the section.

The succeeding 14 metres of the overlying Welton Formation includes the Sciponoceras gracile, Mytiloides labiatus, and Terebratulina lata Zones, the two latter zones forming the base of the base of the Turonian. The main features of this part of the succession include the M. labiatus shell beds near the base and the entry of the ammonite Mammites nodosoides (a worldwide event at this level). Other marker horizons include the first occurrence of flint, the 2 cm Grasby Marl and near the top of the section, a red ferruginous marl. These higher beds are generally poorly fossiliferous.

References

Smart, J. O. & Wood C. J. 1976. Field meeting in South Humberside. Proceedings of the Yorkshire Geological Society 40, 586-593.

Wood, C. J. & 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. 1980. Upper Cretaceous, Eastern England from the Tees to the Wash. British Regional Geology (London H.M.S.O.) 9, 92-105.

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.

Wright, C. W. & Wright, E. V. 1942. The Chalk of the Yorkshire Wolds. Proceedings of the Geologists Association London 53, 112-127.

Copyright Hull Geological Society.