South-west England Chalk Group Lithostratigraphy: Jarvis & Woodroof (1984) & Jarvis & Tocher (1987) - Beer Roads Flinty Chalk Member

The Beer Roads Flinty Chalk, named after Beer Roads [SY 232 892], Devon, comprises smooth-textured, abundantly flinty chalk, with wavy-bedded and laminated marly chalk beds and marl seams (Jarvis & Woodroof, 1984). The flints are characteristically small and spikey, but large nodular forms also occur, and most represent the preserved burrow systems of soft-bodied animals (Woods, 1999). At Beer Roads the member is 23 m thick,expanding to c. +30 m locally (Woods, 1999). Key markers are two intervals of flint-free, wavy-bedded marly chalk, named (in ascending order) by Rowe (1903) the 'Two Foot Band' and the 'Four Foot Band'., the marl seams at the base of which were named respectively the Common Hill Marl and the Smuggler's Cave Marls by Jarvis & Tocher (1987). The base of the Beer Roads Flinty Chalk is immediately above the top surface of Flinty Hardground 5, or where absent, immediately above the top of the Branscombe Hardground (at the top of the underlying Connetts Hole Nodular Chalk Member) (Jarvis & Woodroof, 1984). The top of the member is the lowest occurrence of regularly nodular chalk that defines the base of the overlying St Margarets Member (Jarvis & Tocher, 1987). Typical fossils in the Beer Roads Flinty Chalk are the brachiopod Terebratulina lata, the inoceramid bivalve Inoceramus cuvieri and the large, agglutinating foraminifera Labyrinthidoma (= Coskinophragma) (Woods, 1999).

Macrofossil Biozonation: Jarvis & Woodroof (1984) proposed a largely untested biozonal scheme based on inoceramid bivalves, which is not used herein. Recent work (Woods, 1999) on the successions in south-east Devon shows that the Beer Roads Flinty Chalk of Jarvis & Woodroof (1984) belongs to the T. lata Zone.

Correlation: see Correlation with other lithostratigraphical schemes for south-west England

see Correlation with other UK regions

References

JARVIS, I & WOODROOF, P B. 1984. Stratigraphy of the Cenomanian and basal Turonian (Upper Cretaceous) between Branscombe and Seaton, S E Devon, England. Proceedings of the Geologists' Association, Vol. 95 (3), 193-215.

JARVIS, I & TOCHER, B A. 1987. Field Meeting: the Cretaceous of SE Devon, 14 - 16th March, 1986. Proc. Geol. Ass., Vol. 98 (1), 51-66.

WOOD, C. J. 1996. Upper Cretaceous: the Chalk Group. In SUMBLER, M. G., British Regional Geology: London and the Thames Valley. Fourth Edition. (London: HMSO for the British Geological Survey).

WOODS, M A.1999. Draft contribution to the sheet description of the Sidmouth district (Sheet 326): Cretaceous. British Geological Survey Technical Report, WH/99/28R.

See: marl, Connetts Hole Nodular Chalk, St. Margaret's Member