235 

 GAULT FORAMINIFERA FROM FORD, BUCKS. 



E. MOLLIS, F.Z.S., AND E. NEAVERSON, B.SC, F.G.S. 



In past times the Gault was worked at Ford, four miles south- 

 west of Aylesbury, for phosphatic nodules (' coprolites '), 

 which occur at the top of the Lower Gault. The workings were 

 abandoned many years ago, and nothing now remains but the 

 spoil-heap, which is completely grassed over. Judging by 

 specimens of ammonites in the Bucks. County Museum, Ayles- 

 bury, the deposit worked belonged to the zones of Hoplites 

 auritus and H. lautus. At the typical locality of Folkestone, 

 these zones occupy 17 feet out of a total of 99 feet for the whole 

 of the Gault ; but at Ford only three or four feet seem to have 

 been worked. Critical zonal study is, of course, impossible ; 

 but residues obtained by washing the clay yielded a large series 

 of Foraminifera. Specimens of these have been deposited in 

 the geological collection of the Bucks. County Museum. 



The Gault Foraminifera of the classic exposure at Folkestone 

 have been fully investigated by F. Chapman {Journ. Roy. 

 Micr. Soc, 1891-8). In all 265 species are described and 

 figured from the Gault, of which some 145 occur in the lower 

 zones. At Ford, 135 species have been identified, some of 

 which occur only in the Upper Gault of Folkestone. The Ford 

 specimens approximate closely to those from Folkestone. 



The residues obtained by washing the clay consist chiefly 

 of quartz-sand, together with grains of glauconite, limonite 

 and other minerals. Many of the glauconite-grains are casts 

 of Foraminifera, and broken tests of Cristellaria, Pulvinidina, 

 etc., are often seen to be filled with glauconite. Some tests 

 of Foraminifera are infilled with marcasite. The grains of 

 glauconite often show a brown colour on the surface, due 

 probably to decomposition, as these grains become green on 

 boiling in dilute hydrochloric acid. Grains of garnet also 

 occur, but are not abundant. Of the organic contents, Foram- 

 inifera are most abundant ; ostracods, shell fragments and 

 sponge-spicules are common, while echinid-spines and fish- 

 teeth are also seen. 



LIST OF THE FORAMINIFERA. 

 A =^.abundant ; C = common ; F = frequent ; R = rare ; V.R.=very rare^ 



SPECIES. 



Range in time. 



Occur- 

 rence at 

 Ford. 



Nubeciilaria nodulosa Chap. . 



Spiroloculina nitida d'Orb. . 



Miliolina venusta (Karrer) . 



',, • tricarinata (d'Orb.) 



,, ferussacii (d'Orb.) 



Gault 



Middle Jurassic to Recent 



Gault to Recent 



1921 July 1 



