36 GEOLOGY OF THE ISLE OF WIGHT 



The Wealden of the Isle of Wight are some 700 feet thick, 

 in Kent a good deal thicker, the Hastings Sands, the 

 lower part of the formation, being below the horizon 

 occurring in the Island : the Lower Greensand is some 

 800 feet thick. In the ancient rocks of Wales, the 

 Cambrian and Silurian strata, are thousands of feet of 

 deposits, mostly laid down in fairly shallow water. In 

 such cases there has been a long-continued deposition of 

 sediment, while a subsidence of the area in which it was 

 laid down has almost exactly kept pace with the deposit. 

 It is difficult not to conclude that the subsidence has been 

 caused by the weight of the accumulating deposit, con- 

 tinuing until some world-movement of the contracting 

 globe has produced a compensating elevation of the area. 



