Southern Region Chalk Group Lithostratigraphy: Traditional Classification - Top Rock

The Top Rock is the name given to an indurated chalk bed, comprising a group of hardgrounds, developed in some parts of the UK, normally a short distance above the Chalk Rock. It was first described by Chatwin & Withers (1908), and redefined by Bromley & Gale (1982) as 'the lithified horizon that terminates the nodular [chalk] unit overlying the Chalk Rock'. In some historical accounts it has been confused with the Chalk Rock (see Bromley & Gale, 1982). The Top Rock is practically undeveloped in the southern region, except in the Kent coast succession around Dover, where it consists of 0.6 m of strongly developed yellowish nodular chalk surmounted by a hardground (Shephard-Thorn, 1988).

Macrofossil Biozonation: topmost S. plana Zone and lower M. cortestudinarium Zone

Correlation: see Correlation with other Southern Region Chalk Group classifications

see Correlation with other UK Chalk Group successions

References

BROMLEY, R G & GALE, A S. 1982. The lithostratigraphy of the English Chalk Rock. Cretaceous Research, Vol. 3, 273 - 306.

CHATWIN, C P & WITHERS, T H.1908. The zones of the Chalk in the Thames Valley between Goring and Shiplake. Proceedings of the Geologists’ Association. Vol. 20, 390-420.

SHEPHARD-THORN, E R. 1988. Geology of the country around Ramsgate and Dover. Memoir of the British Geological Survey.

See: Top Rock (of Type Area), hardground