Southern Region Chalk Group Lithostratigraphy: Bristow et al. (1997) - West Melbury Marly Chalk
The West Melbury Marly Chalk (stratotype: old Melbury Quarry [ST 8753 2015] ) comprises rhythmically bedded soft grey marls and buff, grey and off-white marly chalk, with beds of hard limestone, and is between 15 and 30 m thick (Bristow et al., 1997). The base of the unit is the top of the Glauconitic Marl (where present), or at the first significant upward appearance of chalk or marl (Bristow et al., 1997). The top of the West Melbury Marly Chalk is marked by a feature-forming indurated limestone characterised by the inoceramid bivalve Inoceramus tenuis, and named the Tenuis Limestone (Bristow et al., 1997). The West Melbury Marly Chalk equates with the greater part of the Chalk Marl of traditional classifications, but is thin or absent in south Dorset (eg. Punfield Cove) due to the influence of a structural high named the Mid-Dorset Swell (Bristow et al., 1997).
Macrofossil Biozonation: M. mantelli Zone, M. dixoni Zone, C. inerme Zone & basal A. rhotomagense Zone
Correlation: see Correlation with other Southern Region Chalk Group classifications
see Correlation with other UK Chalk Group successions
BRISTOW, C. R., MORTIMORE, R. N. & WOOD, C. J. 1997. Lithostratigraphy for mapping the Chalk of southern England. Proceedings of the Geologists' Association, Vol. 108, 293-315.
See: Glauconitic Marl (Bristow et al., 1997), chalk, marl, Tenuis Limestone, Chalk Marl (traditional classification)