212 GEOLOGY OF THE ISLE OF WIGHT. 



St. George^ s Doion to East Coioes and Osborne. 



The sinuous outlier of gravel which spreads over the edges of 

 the highly inclined Chalk and Greensands in this Down is one of 

 the most remarkable in the Island, partly on account of its height 

 above the sea and above the neighbouring valleys, and partly on 

 account of the bold feature it presents to the south. The gravel, 

 being thick and coarse, and having been partly cemented into 

 a hard rock by iron oxide, forms an escarpment rivalling that of 

 one of the older sandstones, while its even surface, slanting 

 gently away to the north, resembles a dip-slope. On the north side, 

 the central part of the outlier has been deeply notched by a number 

 of springs, each forming a combe, and producing scenery of 

 remarkable beauty. The gravel stretches away far to the north, 

 both on the east and west sides, along the nearly le\ el tops of 

 ridge."^ composed of all the rocks np to the Chalk- with-Hints. 



The ori<:inal limits of the sheet of gravel, of" which these outliers 

 are remnants, are difficult to determine owing to the vast amount 

 of denudation which they have undergone. On the eastern side, 

 the boundary of the deposit may have run at the foot of the rising 

 slope of Chalk which forms the east end of Arreton Down. On 

 the western side, we find no corresponding feature nearer than the 

 Down beyond Carisbrook. The gap between these two features 

 is nearly three miles broad, and was probably the route by which 

 the enormous masses of flint-gravel and Greensand chert of the 

 neighbourhood of Cowes passed the Downs. 



It should be remembered that the Medina valley, which follows 

 the same general line, is of much later date. It was during the 

 process of its excavation that the old gravels were so extensively 

 eroded, and the features of the old valley were nearly obliterated. 

 North of the Downs it is scarcely traceable, except by the slight 

 eastward or westward inclination of the gravels towards the 

 Medina. The absence of any definite limits here arises partly from 

 denudation, but partly also from the spreading out of the gravels 

 into wide sheets which range along and slope down towards the 

 .Solent. 



The gravels rest on a plain which slopes north, as mentioned 

 above. The amount of slope may be calculated as follows : — In 

 the western arm o£ St. George^s Down the level falls about 

 90 feet in a mile, or at the rate of 1 in 60. This arm, however, 

 trends towards the Medina; but if a line is taken parallel to the 

 Medina we tind that the fall is less. At St. George's Down the 

 height is about 320 feet ; nearly two miles to the north it sinks 

 to 280 feet— a fall of about 1 in 260. The Whippingham 

 outlier continues the slope down to about 120 feet, giving a 

 general fall of 200 feet in 6 miles, or about 1 in 160. It is 

 noticeable th;>t the rate of fall tends somewhat to decrease as the 

 gravels are folh^wed further from their source. 



Taking next a parallel line about a mile further east we arrive 

 at similar results. In the eastern arm of St. George's Down 

 (^including the Downend outlier) the level falls from 315 feet 



