56 GEOLOGY OF THE ISLE OF WIGHT. 



By tlie side of the high road from Chale to Chillerton a pit 

 shows the base of the Carstone, consistiDg there of a ferruginous 

 grit with a few pebbles at the base, and resting on sand and cLiy 

 with markings resembling fucoids, about 6 feet thick, under which 

 lies white sand. The escarpment continues to grow in importance, 

 but excepting in a lane near Roslin, presents no sections till we 

 reach Rooldey Green, the road-cutting south of which place 

 shows yellow and white laminated sand and loam (Sand-rock 

 Series) in the lower part, and ferruginous sand and loam with 

 some clay nearer to Rookley Green. Thence the Carstone sweeps 

 round to the east and north of Rookley, and crosses the same 

 road south of Blackwater, in a cutting where it rests on white 

 sand. 



It is next seen in small pits near Park Cottage, but is better 

 exposed in a road-cutting at Sandway, 300 yards east of White- 

 croft, where it rests on the white sand previously alluded to 

 (p. 42). 



A short distance to the north, at Marvel Wood, the Carstone 

 rises into one of the boldest escarpments in the Isle of Wight, 

 of which the section was given on p. 42. It here rests on sands 

 in which current-bedding is very conspicuous. The definiteness 

 of its base, taken together with the manner in which it crosses 

 the edges of the current-bedding planes of the strata below, gives 

 a strong appearance of unconformity, which is heightened by the 

 fact that the grey sand, 3 feet thick, on which the Carstone 

 reposes, looks as if it had been " reconstructed " from the clays 

 and white sands of the Sand-rock Series. The mapping of the 

 Island as a whole did not, however, support the idea of an un- 

 conformity at this horizon, though there may have been local 

 erosion and redeposition. The base of this subdivision may be 

 followed along Marvel Wood to the head of the valley on the west 

 side, where two small pits give a similar section. 



The Carstone is next seen in the lanes near Newclose House, but, 

 owing to the rapidly increasing dip, the outcrop becomes narrow, 

 and the escarpment insignificant. On the east side of the Medina 

 it is seen in the lane leading up the hill past Standen. The upper 

 beds of the Sand-rock Series are also brown here, but may be 

 distino-uished without difficultv from the coarse ferruo-inous grit 

 of the Carstone. 



From St. George's Down eastwards the position of the Carstone 

 is marked by a slight rise in the ground, and the highly ferruginous 

 soil. The rock is exposed in the road-side at Great East Standen, 

 but does not appear again till we reach a small opening 300 

 yards south-east of Heasley Lodge, where it rests on buff sand. 



At Knighton it forms a fairly well-marked feature, and is 

 exposed in the wooded bank on the east side of the stream, and 

 again in the valley a quarter of a mile west of Kern. East of 

 Kern the dip increases and the outcrop narrows down to a mere 

 line. There is a small exposure 250 yards north-w^est of the 

 Roman Villa at Brading. 



