Southern Region Chalk Group Lithostratigraphy: The North Downs (Robinson, 1986) - Margate Member: Difference between revisions
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The Margate Member (composite stratotype: White Ness [TR 396 710] and Foreness Point [TR 384 716]), with a minimum composite thickness of 22.5 m, comprises poorly flinty, marl-free chalk (Robinson, 1986). The lower boundary of the member is the upper surface of the Barrois Sponge Bed, or where condensed, the Clandon Hardground; truncation of the member by the Palaeogene erosion surface means that there is no upper boundary (Robinson, 1986). Echinoids and crinoids are locally very common, the former including in particular ''Conulus'' and ''Echinocorys'', and the latter ''Uintacrinus'' and ''Marsupites'' (Robinson, 1986). Key marker beds include, in ascending order, Rowe's Echinoid Band, Peake's Sponge Bed, the Palm Bay Echinoid Band and the Foreness Flint (Robinson, 1986). | The Margate Member (composite stratotype: White Ness [TR 396 710] and Foreness Point [TR 384 716]), with a minimum composite thickness of 22.5 m, comprises poorly flinty, marl-free chalk (Robinson, 1986). The lower boundary of the member is the upper surface of the Barrois Sponge Bed, or where condensed, the Clandon Hardground; truncation of the member by the Palaeogene erosion surface means that there is no upper boundary (Robinson, 1986). Echinoids and crinoids are locally very common, the former including in particular ''Conulus'' and ''Echinocorys'', and the latter ''Uintacrinus'' and ''Marsupites'' (Robinson, 1986). Key marker beds include, in ascending order, Rowe's Echinoid Band, Peake's Sponge Bed, the Palm Bay Echinoid Band and the Foreness Flint (Robinson, 1986). | ||
Latest revision as of 12:41, 7 October 2013
The Margate Member (composite stratotype: White Ness [TR 396 710] and Foreness Point [TR 384 716]), with a minimum composite thickness of 22.5 m, comprises poorly flinty, marl-free chalk (Robinson, 1986). The lower boundary of the member is the upper surface of the Barrois Sponge Bed, or where condensed, the Clandon Hardground; truncation of the member by the Palaeogene erosion surface means that there is no upper boundary (Robinson, 1986). Echinoids and crinoids are locally very common, the former including in particular Conulus and Echinocorys, and the latter Uintacrinus and Marsupites (Robinson, 1986). Key marker beds include, in ascending order, Rowe's Echinoid Band, Peake's Sponge Bed, the Palm Bay Echinoid Band and the Foreness Flint (Robinson, 1986).
Macrofossil Biozonation: M. coranguinum Zone (pars), U. socialis Zone, M. testudinarius Zone, O. pilula Zone (pars)
Correlation: see Correlation with other lithostratigraphical schemes for the Southern Region
see Correlation with other UK regions
References
ROBINSON, N D.1986. Lithostratigraphy of the Chalk Group of the North Downs, southeast England. Proceedings of the Geologists' Association, Vol. 97, 141-170.
See: Barrois Sponge Bed, Clandon Hardground (plus key marker beds highlighted above)