. Bulletin of the British Museum (Natural History), Geology. the auritus Subzone, while the rarer, non-phosphatized elements of the fauna indicate a slightly younger horizon. No microfaunal information is available from here. 5. The margin of the Mid-Dorset Swell Since important changes occur adjacent to the Mid-Dorset Swell the area between Warminster and Buckland Newton has been studied in considerable detail. In this region (Fig. 21) the Lower Chalk thins from approximately 60 m in the Westbury area to about 25-30 m in mid-Dorset. Unfortunately, the all-important mid-Cenomanian non-sequence
. Bulletin of the British Museum (Natural History), Geology. the auritus Subzone, while the rarer, non-phosphatized elements of the fauna indicate a slightly younger horizon. No microfaunal information is available from here. 5. The margin of the Mid-Dorset Swell Since important changes occur adjacent to the Mid-Dorset Swell the area between Warminster and Buckland Newton has been studied in considerable detail. In this region (Fig. 21) the Lower Chalk thins from approximately 60 m in the Westbury area to about 25-30 m in mid-Dorset. Unfortunately, the all-important mid-Cenomanian non-sequence is not exposed and the litho- logical sequences must be constructed without reference to one of the more important datum levels within the Lower Chalk. As the thickness of the Lower Chalk is known at several localities some information can be gleaned from the age determinations of the lowest levels. At all the localities studied (Stour Bank (ST 846106, Fig. 22), Mere (ST 804323, Fig. 23) and Maiden Bradley (ST 797390, Fig. 24)) the basal, glauconitic chalk yields a Zone 10 microfauna, although the precise position within that zone cannot be determined. The sequence below this zone is highly complex, and contains a series of boulder or 'popple' beds, greensands, and greensands with MERE (DEAD MAID Qu. WILTSHIRE ST. 804 323 z < z ^^^ >^^^ ^ "^s^ »:!^^. Fig. 23 Microfaunal details. Dead Maid Quarry, Mere, Wiltshire. See Fig. 20 for explanation of letter code. 78. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original British Museum (Natural History). London : BM(NH)
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