South-west England Chalk Group Lithostratigraphy: Jarvis & Woodroof (1984) & Jarvis & Tocher (1987) - Ramsgate Chalk Formation: Difference between revisions

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Jarvis & Tocher (1987) used Robinson's (1986) North Downs lithostratigraphical nomenclature for the higher part of the Chalk Group in south-east Devon, believing the successions of the two areas to be broadly comparable, though not correlatable in detail. The Ramsgate Chalk Formation (sensu Jarvis & Tocher, 1987) mostly comprises hard, nodular , flinty chalk with marl seams and hardgrounds, named St Margaret's Member, which at Pinhay Cliffs [SY 312 906] is c. 28 m thick (Jarvis & Tocher, 1987). The latter is very locally overlain by a thin succession of soft, smooth-textured chalk with common large tabular and semitabular flints, named the Broadstairs Member, and c. 13 m thick at Pinhay (Jarvis & Tocher, 1987; Woods, 1999). The base of the formation is the lowest occurrence of regularly developed hard, nodular chalk that defines the St Margarets Member, and the top is the Palaeogene erosion surface (Jarvis & Tocher, 1987). The succession is locally very fossiliferous with brachiopods, inoceramid bivalves and echinoids (Woods, 1999).
Jarvis & Tocher (1987) used Robinson's (1986) North Downs lithostratigraphical nomenclature for the higher part of the Chalk Group in south-east Devon, believing the successions of the two areas to be broadly comparable, though not correlatable in detail. The Ramsgate Chalk Formation (sensu Jarvis & Tocher, 1987) mostly comprises hard, nodular , flinty chalk with marl seams and hardgrounds, named St Margaret's Member, which at Pinhay Cliffs [SY 312 906] is c. 28 m thick (Jarvis & Tocher, 1987). The latter is very locally overlain by a thin succession of soft, smooth-textured chalk with common large tabular and semitabular flints, named the Broadstairs Member, and c. 13 m thick at Pinhay (Jarvis & Tocher, 1987; Woods, 1999). The base of the formation is the lowest occurrence of regularly developed hard, nodular chalk that defines the St Margarets Member, and the top is the Palaeogene erosion surface (Jarvis & Tocher, 1987). The succession is locally very fossiliferous with brachiopods, inoceramid bivalves and echinoids (Woods, 1999).


Revision as of 15:20, 7 October 2013

Jarvis & Tocher (1987) used Robinson's (1986) North Downs lithostratigraphical nomenclature for the higher part of the Chalk Group in south-east Devon, believing the successions of the two areas to be broadly comparable, though not correlatable in detail. The Ramsgate Chalk Formation (sensu Jarvis & Tocher, 1987) mostly comprises hard, nodular , flinty chalk with marl seams and hardgrounds, named St Margaret's Member, which at Pinhay Cliffs [SY 312 906] is c. 28 m thick (Jarvis & Tocher, 1987). The latter is very locally overlain by a thin succession of soft, smooth-textured chalk with common large tabular and semitabular flints, named the Broadstairs Member, and c. 13 m thick at Pinhay (Jarvis & Tocher, 1987; Woods, 1999). The base of the formation is the lowest occurrence of regularly developed hard, nodular chalk that defines the St Margarets Member, and the top is the Palaeogene erosion surface (Jarvis & Tocher, 1987). The succession is locally very fossiliferous with brachiopods, inoceramid bivalves and echinoids (Woods, 1999).

Macrofossil Biozonation: T. lata Zone (pars), S. plana Zone, M. cortestudinarium Zone, M. coranguinum Zone (pars) (Woods, 1999).

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

see Correlation with other UK regions

References

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.

ROBINSON, N D.1986. Lithostratigraphy of the Chalk Group of the North Downs, southeast England. Proceedings of the Geologists' Association, Vol. 97, 141-170.

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: Ramsgate Chalk Formation (Robinson, 1986), marl, flint, hardground, St. Margaret's Member, Broadstairs Member

[Category:South-west England Chalk Group Lithostratigraphy: Jarvis & Woodroof (1984) & Jarvis & Tocher (1987) | 009]]

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