66 MIDDLE ALBIAN STRATIGRAPHY 



fossils were found, and indeed, the only fossils recorded from the lower part of the 

 Gault in this area were obtained from a nodule bed stated to occur at about 10 feet 

 (3-04 m.) above the base of the formation (Pringle & Chatwin in Sherlock 1922 ; 9). 

 This bed has yielded an upper Albian fauna (Jukes-Browne 1900 ; 278 whose inclusion 

 of tins horizon in the Lower Gault was an error : C. W., & E. V. Wright 1939 ; 115- 

 116 : Spath 1943 ; 746). Kitchin & Pringle took this fact to confirm an extreme 

 conclusion, stating that the Lower Gault had been overstepped by the Upper Gault 

 in this area (1922 ; 164-5). Pringle & Chatwin (in Sherlock 1922 ; 8) were more 

 objective in that they pointed out that there was no evidence at that time for the 

 presence of the Lower Gault. Spath (1943 ; 746) although vague was a little more 

 cautious. 



Important new information, demonstrating the presence of the spathi Subzone in 

 the lower beds of the Gault, was obtained by the writer from a trench dug by Messrs. 

 S. A. Leach & Co., during the laying of sewer pipes in January 1967. This very 

 temporary section was situated only a few hundred yards S. of the Walton Cutting 

 and the sequence is shown graphically in text-fig. 28. 



No fossils were obtained from Beds 1-5 and their exact age is uncertain. Bed 6 

 yielded a small bivalve fauna consisting mainly of a small Ostrea and a few specimens 

 of Nucula together with a single example of Neohibolites minimus. The shell seam 

 at the base of bed 7 contains numerous Inoceramus concentricus and some partly- 

 phosphatised Hoplites (H.) with simple dentatus ribbing, all with the nacreous shell. 

 The species include H. (H.) dentatus and H. (H.) cf . maritimus some being quite large 

 — 6 to 8 inches in diameter, and the specimens of I. concentricus are also of large size. 

 A few specimens of Dentalium and Nucula also occur. This same faunal assemblage 

 occurs in the remainder of Bed 7 but it is crushed flat. The ammonites indicate the 

 lower part of the spathi Subzone, and it is unfortunate that no higher levels were 

 exposed at this locality. 



Another ' cut and fill ' trench exposing higher beds was excavated in February 

 1967 in the area approximately 1475 yds a little S. of E. of the trench described 

 above. This trench was dug to a depth of 6 feet and extended from a point about 

 600 yds NNE. of Stoke Grange to a point about 400 yds. ENE. of Stoke Grange 

 (SP 8357512340 to SP 83801 190), to the NE. of the A 413 (Wendover Road), Ayles- 

 bury. The trench was apparently cut in the direction of strike and exposed weathered 

 dark blue-grey clay with small buffish phosphatic nodules and patches. No 

 determinable fossils were found except at the field boundary (SP 83621225) where 

 two very badly preserved fragments of ammonites were seen. One was comparable 

 to Dimorphoplites, the other an equally poor fragment of Euhoplites. Together they 

 suggest an horizon below that exposed in the trenches along the A 41 in the Aston 

 Clinton area described by Wright & Wright (1939) which at certain points yielded an 

 orbignyi Subzone fauna. 



There is no doubt that the thickness of sediments below the orbignyi Subzone 

 nodule bed in the Aylesbury area exceeds 10 feet (3-04 m.) and it is likely that there 

 is a good deal more. 



