PLATEAU GRAVELS. 211 



This point was first noticed by Mr. Codrington,* who remarked 

 that the high-level plains of the New Forest and the country 

 bet^veen Poole and Southampton Water, generally covered with 

 gravel or brick-earth, are portions of a table-land with a gradual 

 southern slope. He further observed that the gravel covering the 

 hills from St. George's Down to Norris "^ coincides with a plain 

 having a uniform slope to the north," thus giving proof that 

 the excavation of the Solent Valley was in progress during the 

 deposition of the Plateau Gravels. 



The great antiquity of parts of the Plateau Gravels is forcibly 

 brought to mind when we study the vast amount of denudation 

 that has been effected since their deposition, and the question 

 naturally arises whether these gravels may not be in part contem- 

 poraneous with the Glacial Deposits of the north of England. 

 This question cannot be fully answered until the mapping of the 

 gravels on the main land is completed, but it will perhaps not be 

 premature to point out how far the evidence in the Isle of Wight 

 goes in support of such a supposition. 



In the first place, though no organic remains have been found in 

 the Plateau Gravels, the mammoth {Elejjhas primitj/enius) and 

 and Rhinoceros have been found in the Valley Gravels, which are 

 unraistakeably later in date. 



Secondly, the amount of denudation which has taken place in. 

 the Isle of Wight, since the Plateau Gravels were laid down, is 

 fully as great as that which the Glacial Deposits have undergone in 

 other parts of England ; tlie valleys which cut up the former 

 into outliers are as broad and as deep as those which have been 

 excavated in the Glacial Beds. To quote a single example — the 

 gravel plateau of St. George's Down terminates soutnwards and 

 westwards in a bold bank at a height of 363 feet above Ordnance 

 Datum, or at a height of no less than 313 feet above the bottom 

 of the valley, this amount therefore representing the depth of 

 valley cut out since the plateau formed part of the general 

 surface. 



Thirdly, the gravels are precisely similar in their mode of 

 occurrence, and in the amount of denudation they have under- 

 gone, to those which overspread the chalk hills on the northern 

 side of the Thames valley, in Buckinghamshire and Hertfordshire. 

 A part of these gravels is known to be of Glacial Age by the 

 fact that they underlie outliers of Boulder Clay in the neighbour- 

 hood of Watford and Finchley. The othej's to the west are 

 inferred to be of the same age from the similarity in their 

 character and position. t 



Lastly, the gravels and the older strata on which they im- 

 mediately rest, are sometimes contorted or disturbed in a 

 manner strongly suggestive of the action o£ ice. Such appearances 

 have been seen below the older gravels only. 



* On the Superficial Deposits of the South of Hampshire and the Isle of Wight 

 Quart. Journ. Geol. Soc, vol. xxvi. pp. 528-551. 1870. 



t They are described in the Memoir on the Geology of London, &c., by W, 

 Whitaker. 1889. Chap .19. 



O 2 



