160 GEOLOGiT OF THE ISLE OF WIGHT. 



but a single bed, the aggregate thickness was three feet six inches ; 

 viz., clay six inches ; limestone, one foot ten inches ; and green 

 marl, one foot two inches. Above the carbonaceous clay is a soft 

 cream-coloured earthy limestone, also containing Limncea and 

 Planorhis. The thickness of this upper limestone, which has 

 apparently a denuded surface, varies considerably, but from 5 to 

 8 feet of it appear from beneath the white sands which form the 

 lowest member of the gravel series constituting the summit of 

 Headon Hill. 



In a section pointed out by Mr. Keeping, further north, the 

 Bulimus limestone, uneven and irregular, is covered in places 

 with brown and black carbonaceous clay, filling irregularities in its 

 surface. The green clay with Cyrena above the thick limestone 

 (here from one foot nine inches to four feet thick) contains a 

 layer of Cyrena fifteen inches from the bottom of the bed, while 

 the limestone, which (in addition to Limnaa and Planorhis) also 

 contains Cyrena in the lower three inches, is only one foot thick. 

 The clays above are irregular, and of variable thickness, but 

 average about two feet, the lower six to nine inches of which is 

 brown clay, becoming occasionally dark and carbonaceous towards 

 the bottom, and dark grey carbonaceous clay six to fifteen inches, 

 the upper six to nine inches of which frequently consist of lignite ; 

 two or three inches of sand, with carbonaceous laminae, succeeded 

 by green marl, complete the section. Hard thick beds are quarried ' 

 at the eastern extremity of this outlier. 



Another outlier, over three-quarters of a mile long, covers the 

 high ground upon which Hill Farm is built. A pit has been 

 opened in it at the end of the lane running in a north- westerlv 

 direction from the farm. In the road to More Green casts of 

 Limncpa, Planorhis, and small Helix have been found. A short 

 distaii further north the limestone is overlain by green clay 

 containing comminuted fragments of Cyrena. At its northern 

 extremity, the limestone based on red clay is cream-coloured, soft 

 and earthy (somewhat similar to dried mortar), becoming, how- 

 ever, occasionally harder in places, and assuming a kind of 

 tufaceous character. Another inconsiderable patch of limestone 

 similar to that last noticed, occurs half way between it and 

 Norton. 



Sconce. — For years this locality has yielded many of the most 

 interesting fossil shells found^in the Isle of Wight Tertiary Series, 

 especially species of terrestrial origin. Not a few of the rarer 

 and more curious pulmoniferous molluscs, so well figured and 

 described in Mr. Frederick Edwards's excellent monograph, were 

 discovered at Sconce. At present (1888) the section"; being much 

 overgrown, the following details are taken from Forbes' Memoir. 



" The Bembridge limestone at Sconce, a mass of limestone and 

 marls, is from IG to 20 feet in thickness. It rises with the slope 

 of the hill opposite Yarmouth, and forms the partly mural crest 

 cropping out at Cliff' End. The entire thickness is composed of 

 calcareous beds passing into each other, very concretionary. 



