Revieu-fi—Juhcs-Broinic 4" EilJ — Gault and IT. Greenland, 87 



of the zones of the Selbornian as they" are exposed in different 

 counties, beginning with the easterly exposure on the coast at 

 Folkestone to its most westerly extension on the Haldon Hills, near 

 Exeter, from thence returning in a north-easterly direction through 

 the counties of Wilts, HerUs, Oxford, Buckingham, Cambridge, 

 Norfolk, Lincoln, and York. The changes in the character of tlie 

 beds in areas not far removed are somewhat striking : we can only 

 briefly mention some of them. 



Beginning at the well-known coast section at Folkestone, the 

 Lower Gault (excluding the debateable G feet of sand of the Am. mnm- 

 millatns zone) consists mainly of grey and dark fossiliferous clays, 

 about 29 feet in thickness. The lower portion of the Upper Gault 

 is likewise of marly clays, having a thickness of 50 feet, and tiiese 

 are overlaid by glauconitic sands and buff marls with but a few 

 fossils, 27 feet in thickness. Thus the total thickness of the 

 Selbornian at this spot is 106 feet, and the materials are mostly 

 marly or clayey. 



In Surrey the Lower Gault consists of clays somewhat similar 

 to those in Kent, but fossils are comparatively scarce in them. No 

 definite boundary' between the Upper and Lower Gault is known : 

 the upper beds are of a more sandy character, and they are succeeded 

 by the ]\Ialm and Firestone (Merstham Beds), representing the Upper 

 Gault and Upper Greensand, which are 60-80 feet in thickness 

 in the west of the county. The author considers that the entire 

 thickness of the Malmstone belongs to the zone of Am. voslralns, 

 together with the 8-10 feet bed of greenish sand which comes in 

 between the Malmstone and the base of the Chalk Marl, and that 

 the zone of Pecten asper is not represented. We do not find any 

 reference to the excellent section of the Merstham Beds exposed 

 in the last two or three years in the new cutting of the London, 

 Brighton, and South Coast Railway at Merstham. 



The Selbornian is well shown in the coast sections of South 

 Dorset and Devon from Golden Cap to Axmouth. The lowest beds 

 are, at Golden Cap, pebbles, sands, and sandy clays, resting on the 

 Lias, nearly 30 feet in thickness; they contain Gault fossils, and are 

 referred to the upper part of the Lower Gault ; above these is a series 

 of greenish and yellowish glauconitic sands, about 100 feet in thick- 

 ness, which may represent the zone of Am. roslratiis, and over these 

 are some thin chert beds. Further westward, at Black Ven, the 

 sandy beds representing the Gault, containing some obscure fossils, 

 reach a thickness of about 180 feet, and the overlying chert beds, 

 belonging to the highest division of the Upper Greensand, are 40 feet 

 in tliickness. 



At VVhitecliff, South Devon, the sands below the chert beds, 

 forming the lower division of the Upper Greensand, contain the 

 same fossils as occur in the Blackdown Beds, and are inchnled in the 

 zone of Am. rostrutns. They are less than 90 feet in thickness. At 

 Hooken Cliff and Whitecliff, the chert beds of the highest division 

 of the Upper Greensand reach a maximum thickness of 70-80 leet : 

 they contain species of JExogyra and Oibitolina coucava, but Feclen 



