South-west England Chalk Group Lithostratigraphy: Jarvis & Woodroof (1984) & Jarvis & Tocher (1987) - Hooken Nodular Limestone Member: Difference between revisions
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The Hooken Nodular Limestone, broadly equating with A2 of Jukes-Browne & Hill (1903), is named after Hooken Cliffs [SY 219 879], Devon, where it reaches a maximum thickness of 5 m. It comprises medium to light grey, bioclastic, rubbly limestone, with an abundant macrofauna (Jarvis & Woodroof, 1984) of mostly reworked ammonites, echinoids, brachiopods and bivalves. The member locally thins to less than 0.25 m, and is absent at some localities (Jarvis & Woodroof, 1984). The base of the member is immediately above the parting formed by the Weston Hardground at the top of the underlying Pounds Pool Sandy Limestone, and the top is defined by the upper surface of a heavily mineralised hardground, named the Kings Hole Hardground (Jarvis & Woodroof, 1984). | The Hooken Nodular Limestone, broadly equating with A2 of Jukes-Browne & Hill (1903), is named after Hooken Cliffs [SY 219 879], Devon, where it reaches a maximum thickness of 5 m. It comprises medium to light grey, bioclastic, rubbly limestone, with an abundant macrofauna (Jarvis & Woodroof, 1984) of mostly reworked ammonites, echinoids, brachiopods and bivalves. The member locally thins to less than 0.25 m, and is absent at some localities (Jarvis & Woodroof, 1984). The base of the member is immediately above the parting formed by the Weston Hardground at the top of the underlying Pounds Pool Sandy Limestone, and the top is defined by the upper surface of a heavily mineralised hardground, named the Kings Hole Hardground (Jarvis & Woodroof, 1984). | ||
Latest revision as of 14:06, 7 October 2013
The Hooken Nodular Limestone, broadly equating with A2 of Jukes-Browne & Hill (1903), is named after Hooken Cliffs [SY 219 879], Devon, where it reaches a maximum thickness of 5 m. It comprises medium to light grey, bioclastic, rubbly limestone, with an abundant macrofauna (Jarvis & Woodroof, 1984) of mostly reworked ammonites, echinoids, brachiopods and bivalves. The member locally thins to less than 0.25 m, and is absent at some localities (Jarvis & Woodroof, 1984). The base of the member is immediately above the parting formed by the Weston Hardground at the top of the underlying Pounds Pool Sandy Limestone, and the top is defined by the upper surface of a heavily mineralised hardground, named the Kings Hole Hardground (Jarvis & Woodroof, 1984).
Macrofossil Biozonation: (see under A2 of Jukes-Browne & Hill (1903))
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.
JUKES-BROWNE, A J & HILL, W.1903. The Cretaceous rocks of Britain. Vol. 2 - The Lower and Middle Chalk of England. Memoir of the Geological Survey of the United Kingdom.
See: Cenomanian Limestone Bed A2, hardground, Pounds Pool Sandy Limestone, Weston Hardground