South-west England Chalk Group Lithostratigraphy: Jukes-Browne & Hill, 1903, 1904 - Cenomanian Limestone Bed A1
This interval is generally described as an indurated calcareous grit by Jukes-Browne & Hill (1903), containing large quartz grains and locally abundant specimens of the coral-like sponge Acanthochaetetes ramulosus (formerly Ceriopora ramulosa ).
Macrofossil Biozonation: Modern biostratigraphical studies show that A1 belongs to the M. mantelli Zone (Wright & Kennedy, 1984).
Correlation: see Correlation with other lithostratigraphical schemes for south-west England
see Correlation with other UK regions
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.
WRIGHT, C W & KENNEDY, W J. 1984. The Ammonoidea of the Lower Chalk. Part I. Monograph of the Palaeontographical Society. London: 1-126, pls 1- 40 (Publ. No. 567, part of Vol. 137 for 1983).