IN THE ANGLO-PARIS BASIN 



53 



other than that recorded by Jukes-Browne (1900 ; 163-4), Welch and Robbie (in 

 Wilson, Welch, Robbie & Green 1958 ; 148-152) 1 , Reid (1903 ; 34-35), Osborne- 

 White (1923 ; 49-50) and Smart (1955 ; 43-4)- It is apparent that Middle Albian 

 sediments occur north-eastwards from the area of Beaminster for although am- 

 monites have not been found, Inoceramus concentricus has been recorded from a 

 number of sections and in this context definitely indicate a Middle Albian age. From 

 the coast between Thorncombe Beacon and Black Ven (p. 51), Middle Albian 

 sediments thin markedly inland in places to less than 10 feet (3-04 m.) to thicken 

 again in the area of Toller Porcorum (SY 562974) S. of Evershot, and also in the out- 

 crop N. of Evershot eastwards from West Chelborough (Welch and Robbie in Wilson 

 et al., 1958). The Gault continues to thicken eastwards and in the region between 

 Alton Pancras and Ansty, Smart records a thickness ranging from 25-35 feet (1955 ; 

 42-4). The increasing thickness is maintained up to Okeford Fitzpaine. 



w 



Black Van 





Osmington 



Islaof Wight 



E 



Sussex 





"\ 



-— iiate) 



ml ermediu s 





^^--^^ spa th 1 



^^-vT~-^_ (early) 



\ \ 





Fig. 23. Sketch section, from W. to E. across the Late Jurassic-early Cretaceous modified 

 Wessex basin in the area of the south coast, demonstrating the transgressive nature of the 

 Middle Albian sediments and the diachronous nature of the base. 



It is very regrettable that no good sections are now available throughout this long 

 strip of outcrop (text-fig. 18). The sequence seen on the coast between Thorncombe 

 Beacon and Black Ven, with its development of the intermedins Subzone of the 

 loricatus Zone has passed in the area of Okeford Fitzpaine to a sequence showing the 

 development of the eodentatus, lyelli & spathi Subzones of the dentatus Zone. In this 

 latter area it is underlain by deposits of mammillatum Zone age absent at the coastal 

 section to the SW. This difference in sequence is made somewhat significant by a 

 comparison with the sections in the Pays de Caux in northern France (p. 101), and is 

 discussed later in the section dealing with the conditions of deposition (p. 142). 



1 It is worth stating here that the stream and river sections described by the Survey officers are only 

 well visible in periods of drought (cf. Dewey 1934 ; 42). 



