Chalk Group Lithostratigraphy: East Anglia - Catton Sponge Bed

The Catton Sponge Bed, with its stratotype locality at Catton Grove [TG 2289 1094], Norwich, comprises two main beds of spongiferous chalk capped by hardgrounds (Wood, 1988). The hardgrounds are designated I and II in ascending stratigraphical order, the highest being the most conspicuous (= 'main' hardground of Wood, 1988) characterised by accumulations of abraded specimens of the belemnite Belemnitella, and glauconitised chalk pebbles (Wood, 1988). Peake & Hancock (1970) similarly assigned two beds of spongiferous chalk to the Catton Sponge Bed, but the lower of these equates with both hardgrounds described by Wood (1988). The upper sponge bed of Peake & Hancock (1970) was designated Hardground III by Wood (1988), but it lacks a well defined top, is only incipiently developed, and was not regarded as part of the Catton Sponge Bed by Wood (1988), who thereby assigned it to the base of the overlying Beeston Chalk. The Catton Sponge Bed (sensu Wood, 1988) marks the top of the Weybourne Chalk, and equates with the lowest of three sponge beds on the foreshore at Sherringham beneath the lifeboat station [TG 1565 4325] (Pitchford, 1990a). In the BGS Trunch Borehole [TG 2933 3455], the Catton Sponge Bed is possibly represented by a spike in the resistivity and sonic logs at a depth of 154.7 m, which is in an interval of core loss (Arthurton et al., 1994).

Macrofossil Biozonation: B. mucronata Zone

References

ARTHURTON, R S, BOOTH, S J, MORIGI, A N, ABBOTT, M A W & WOOD, C J. 1994. Geology of the country around Great Yarmouth. Memoir of the British Geological Survey.

PITCHFORD, A J.1990a. A Summary of the stratigraphy of current exposures of Belemnitella mucronata Zone Chalk (Campanian, Upper Cretaceous) in Norfolk. Bulletin of the Geological Society of Norfolk, Vol. 40, 3-24.

WOOD, C J. 1988. The stratigraphy of the Chalk of Norwich. Bulletin of the Geological Society of Norfolk, No. 38, 3-120. See: hardground, Weybourne Chalk, spongiferous chalk