DISTURBANCES AND FAULTS. 245 



On the south side of the central range of Downs, the strata 

 rapidly curve over and assume a horizontal position at a distance 

 varying from one to two miles south of the region in which they 

 are vertical. They never present, however, so sharp a fold as that 

 seen In the Bembridge Limestone in Whitecliff Bay. 



The central range consists of two separate axes, which may be 

 conveniently named the Sandown and the Brixton anticlines. 



The first appearance of the Sandown anticline in the Tertiary 

 area west of Calbourne has already been referred to, and its 

 subsequent course eastwards by Arreton to Sandown Level was 

 noted in describing the Lower Greensand (pp. 42-44). The axis 

 runs in a nearly straight line due east and west as far as New- 

 church, but then bends round to about E. 18° S., its direction 

 being definitely given by the line of Downs from Ashey to 

 Culver. The strike of the strata forming the Southern Downs is 

 a little north of east, and the two ranges therefore, if prolonged in 

 these directions, would meet at no great distance from the coast 

 near Sandown. The central point between the east and west ends 

 of the axis lies perhaps not far from the centre of the exposure 

 of the Wealden beds, where the strata are horizontal. 



The dip on the north side of the arch formed by the anticline 

 ranges from 60° to verticality, on the south side from 2° to 3°, in 

 accordance with the general rule previously alluded to that the 

 north side Is the steeper in all these anticlines. 



A little north of Shanklin, a gentle anticline, accompanied by 

 :a fault, probably is the continuation of that which has been noted 

 near Gossard Hill, though it cannot be traced through the Lower 

 Oreensand area. This hill itself stands on the northern side of 

 the anticline, the beds showing a northerly dip of about 10°. On 

 the other hand, the large chalk pit on Chilierton Down lies south 

 of the axis, which must therefore run very near the south side 

 of Gossard Hill. The distance between the axes of this and 

 the Sandown anticline amounts to two miles both here and in 

 Sandown Bay. 



The fault at Little Stairs Point occurs on the north side of this 

 anticline and runs about E. 20° S. for the small distance it Is 

 seen In the cliff". It trends therefore nearly parallel to the axis 

 of the anticline, and perhaps replaces it. In order, however, to 

 effect a displacement of the beds corresponding to that of a fold It 

 should have a downthrow to the north, but In reality It throws 

 the strata In the opposite direction. 



South of this small anticline the beds gently roll over and 

 assume the south-easterly dip which prevails through the Southern 

 Downs. The direction of dip Is not constant, but ranges locally 

 from south-east to south and even south-west, as in the reef of 

 Yellow Ledge near Luccomb. But the general direction may 

 be ascertained by taking the levels of the base of the Chalk at 

 various points. In St. Catherine's Down this base Is about 620 

 feet above the sea at the north-west end and 500 feet at the south- 

 east, the dip being south-east. In Appuldurcombe Down the 

 base lies at 600 feet, but falls In a south-south-easterly direction to 



