Southern Region Chalk Group Lithostratigraphy: Traditional Classification - Chalk Rock: Difference between revisions

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Whitaker (1859) introduced the name Chalk Rock for intensely indurated chalk he found amongst specimens in the museum collections of the Geological Survey, and later described its field occurrence, noting that it coincided with the base of the Upper Chalk as then understood (Whitaker, 1861). Subsequently the Chalk Rock became a marker bed for the base of the Upper Chalk, its indurated feature-forming characteristics forming an easily mapped horizon (Jukes-Browne & Hill, 1904). However, in most of southern England the Chalk Rock is almost entirely undeveloped, it being mostly a feature of successions in the Chilterns, the Berkshire and Marlborough Downs. Since the Chalk Rock occurred at the base of regularly flinty chalk, and was also regarded as coincident with the base of the ''S. plana'' Zone (Jukes-Browne & Hill, 1904), the record of common flints or the subjectively assessed base of the ''S. plana'' Zone became criteria for identifying the equivalent horizon of the Chalk Rock in southern England (Mortimore & Wood, 1986).
Whitaker (1859) introduced the name Chalk Rock for intensely indurated chalk he found amongst specimens in the museum collections of the Geological Survey, and later described its field occurrence, noting that it coincided with the base of the Upper Chalk as then understood (Whitaker, 1861). Subsequently the Chalk Rock became a marker bed for the base of the Upper Chalk, its indurated feature-forming characteristics forming an easily mapped horizon (Jukes-Browne & Hill, 1904). However, in most of southern England the Chalk Rock is almost entirely undeveloped, it being mostly a feature of successions in the Chilterns, the Berkshire and Marlborough Downs. Since the Chalk Rock occurred at the base of regularly flinty chalk, and was also regarded as coincident with the base of the ''S. plana'' Zone (Jukes-Browne & Hill, 1904), the record of common flints or the subjectively assessed base of the ''S. plana'' Zone became criteria for identifying the equivalent horizon of the Chalk Rock in southern England (Mortimore & Wood, 1986).



Latest revision as of 11:11, 4 October 2013

Whitaker (1859) introduced the name Chalk Rock for intensely indurated chalk he found amongst specimens in the museum collections of the Geological Survey, and later described its field occurrence, noting that it coincided with the base of the Upper Chalk as then understood (Whitaker, 1861). Subsequently the Chalk Rock became a marker bed for the base of the Upper Chalk, its indurated feature-forming characteristics forming an easily mapped horizon (Jukes-Browne & Hill, 1904). However, in most of southern England the Chalk Rock is almost entirely undeveloped, it being mostly a feature of successions in the Chilterns, the Berkshire and Marlborough Downs. Since the Chalk Rock occurred at the base of regularly flinty chalk, and was also regarded as coincident with the base of the S. plana Zone (Jukes-Browne & Hill, 1904), the record of common flints or the subjectively assessed base of the S. plana Zone became criteria for identifying the equivalent horizon of the Chalk Rock in southern England (Mortimore & Wood, 1986).

Macrofossil Biozonation: traditionally regarded as S. plana Zone, although in the stratotype area includes top T. lata Zone. Since the Chalk Rock is mostly absent in the Southern Region, its inferred horizon was the subjectively assessed base of the S. plana Zone

Correlation: see Correlation with other Southern Region Chalk Group classifications

see Correlation with other UK Chalk Group successions

References

JUKES-BROWNE, A J & HILL, W.1904. The Cretaceous rocks of Britain. Vol. 3 - The Upper Chalk of England. Memoir of the Geological Survey of the United Kingdom.

MORTIMORE, R N & WOOD, C J.1986. The distribution of flint in the English Chalk, with particular reference to the 'Brandon Flint Series' and the high Turonian flint maximum. In SIEVEKING, G de C & HART, M B. The scientific study of flint and chert. Cambridge University Press, Cambridge.

WHITAKER, W. 1859. In A descriptive catalogue of the rock specimens in the Museum of Practical Geology (Ed. A C Ramsay), 2nd edition. London.

WHITAKER, W. 1861. On the "Chalk-rock", the topmost bed of the Lower Chalk, in Berkshire, Oxfordshire, Buckinghamshire etc. Quarterly Journal of the Geological Society of London, Vol. 17, 166-170.

See: Chalk Rock (of Type Area)