64 MIDDLE ALBIAN STRATIGRAPHY 



preserved are from 42 feet 6 inches, 35 feet, 32 feet 6 inches, 30 feet and 22 feet 6 inches 

 above the base of the Gault and the lithology consists essentially of dark fawn-grey 

 silty clay with shelly fossils. There is no need to emphasise that the cores are very 

 incomplete and that no Subzonal limits can be deduced. 



Sections in the Gault were formerly exposed in the area of Thame (Oxon) and 

 mentioned by Davies (1899b ; 160). The only information about the zonal strati- 

 graphy is the comment by Spath that at Priestend (SP 691055) the lower Gault, 

 which was exposed for at least 40 feet (12-16 m.), contained plentiful impressions of 

 ammonites of the dentatus Zone often of unusually large size (1943 ; 746). 



(iv) THAME TO LEIGHTON BUZZARD (BEDFORDSHIRE) 



The published information on the stratigraphy of the Gault between Thame and 

 Leighton Buzzard, a distance of about 19 miles is again not particularly satisfactory. 

 This is due mainly to the paucity of good exposures and, to a certain extent, to the 

 controversies which have tended to colour the accounts. It is apparent that deposits 

 of Middle Albian age are present throughout the area, although they are greatly 

 reduced in thickness in comparison with the alleged sequence at Thame. The 

 Gault rests in this area either upon the Kimmeridge Clay, Portland, Purbeck, or 

 Lower Greensand deposits. 



(a) Long Crendon (Bucks.) 



No section in the Gault now exists at Long Crendon, which is situated about 2-|- 

 miles towards the N W. of Thame, but sections in this outlier were described by Jukes- 

 Browne (1900 ; 277), Davies (1899a ; 22), Lamplugh (1922 ; 40-44), and Kitchin & 

 Pringle (1922 ; 164-5). The sequence has also been discussed by Kitchin & Pringle 

 (1921a ; 62 : 1922 ; 284-5), Spath (1943 ; 746) and Casey (1961a ; 569). Kitchin & 

 Pringle (1921a ; 62 : 1921b ; 174 see also Spath 1943 ; 746) considered that the Upper 

 Gault rested directly upon Purbeck Beds here but the detailed evidence to sub- 

 stantiate this conclusion was not given. 



On three counts it appears certain that Lower Gault is present. It is important 

 to note that Davies (1899a ; 22 : 1899b ; 161) recorded /. concentricus from the 8 feet 

 of Gault then exposed, but no ammonites were discovered and, therefore, the exact 

 age still remains uncertain. In the main outcrop to the S., the lower part of the 

 Upper Albian is quite fossiliferous with orbignyi Subzone ammonites and the ubiquit- 

 ous Inoceramus sulcatus. Also Lamplugh (1922 ; 40-44) demonstrated that a thin 

 development of Shenley Limestone was present below the Gault (see also Casey 

 1961a ; 569). It seems probable, therefore, that Davies' record of /. concentricus is 

 correct, that these clays are of Middle Albian age, and that there is no overlap of 

 Upper Gault in this area as Kitchin & Pringle held. 



(b) Haddenham (Bucks) 



Although no section exists in the main outcrop between Thame and Aylesbury, 

 two ammonites are preserved in the Buckinghamshire Country Museum, Aylesbury, 



