3S6 CRETACEOUS. 



Regis, where it rests upon the Lias Clays ; it is from eighteen to 

 twenty-five feet thick according to Mr. C. Reid ; and consists of dark 

 bkie micaceous sandy clay, which appears to represent the Lower 

 Gault. Among the fossils are CucuUcEa carinata, hioceramtis con- 

 ceniricus, Lima parallela, Pecten orbictclaris, Pinna tetragona, Aporrhais 

 carinata. Ammonites splcndens, etc.^ Here the collector must be 

 careful, as fossils from the Gault and Lias are commingled in the 

 talus of the upper portion of the cliffs. (See Fig. 40.) Mr. De 

 Ranee has noticed the deposit as occurring not only at Black Ven, 

 Golden Cap, and Stonebarrow Hills, but also at Pinhay Cliff;'' 

 westwards in the coast-section the Gault thins out towards 

 Sidmouth. In 1874, Mr. Ussher noticed in the railway-cutting at 

 Wilmington, near Honiton, clayey beds at the base of the Green- 

 sand, which seem to be referable to the Gault ; and this view 

 has been confirmed by the Rev. W. Downes, who has procured 

 a number of fossils from the beds.' 



The Blackdown Beds have by some geologists been regarded as 

 for the most part of Gault age, and placed in the zone o{ Ammonites 

 ijiflatus ; but, as Mr. Downes remarks, there is no boundary be- 

 tween Upper Greensand and Gault in the West of England. 



Inland in Dorsetshire the Gault is well developed below the 

 Upper Greensand of Shaftesbury ; in the Vale of Wardour the Gault 

 is about 75 feet thick, and it has been exposed near Dinton, 

 Fovant, and at Ridge, south-east of Chilmark. The Gault appears 

 as an inlier at Crockerton, south of Warminster, and it has been 

 traced from Westbury (Eden Vale brickyard) to the neighbourhood 

 of Potterne and Devizes, resting indifferently on the Oxford Clay, 

 Corallian rocks, Kimeridge Clay, Portland Sands, and Lower 

 Greensand. (See Fig. 58.) It forms a continuous band stretching 

 into Oxfordshire, and occupying a broad tract around Tetsworth, 

 south-west of Thame. At Towersey near Thame, and Culham near 

 Abingdon, many fossils have been obtained.* (See Fig. 64.) 



In Cambridgeshire the Gault (brickearth of Cambridge) appears 

 as a stiff pale bluish-grey clay, and may be studied in the brick- 

 pits around Barnwell, also west of Soham. Phosphatic nodules 

 occur in the Gault at Upware,- but the principal accumulations of 

 phosphate occur in the Lower Greensand, and at the base of the 

 Chalk. (See p. 377, and sequel.)^ The formation is not known in 

 Lincolnshire or Yorkshire, while much of the so-called Gault of 

 Norfolk may be Chalk Marl. (See sequel.) 



The Gault forms what may be termed an unproductive soil, but it is well adapted 

 for pasture. It is sometimes called 'black land,'*' and there is a village named 

 Blackland, south-east of Calne, which is partly situated on Gault. It forms a flat 



1 E. T. Newton, Cat. Cret. Fossils (Geol. Surv.), 1878; Rev. W. Downes, 

 Q. J. xli. 23. 



2 G. Mag. 1874, p. 252. See also Fitton, T. G. S. (2), iv. 233. 



3 G. Mag. 1886, p. 308. 



* T- Phillips, Q. J. xvi. 309 ; Geol. Oxford, p. 427. 



5 "H. Keeping, G. Mag. 1868, p. 272. 



^ H. W. Bristow, Explan. Sheet 13 (Geol. Surv.), p. 5. 



