CHAPTER VI 

 THE GAULT AND UPPER GREENSAND 



WE have seen how the continent through which the great 

 Wealden river flowed began to sink below the sea level, 

 and how the waters of the sea flowed over what had been 

 the delta of the river, laying down the beds of sandstone 

 with some mixture of clay which we call the Lower 

 Greensand. The next stratum we come to is a bed of 

 dark blue clay more or less sandy, called the Gault. In 

 the upper beds it becomes more sandy and grey in colour. 

 These are known as the " passage beds, " passing into the 

 Upper Greensand. The thickness of the Gault clay 

 proper varies from some 95 to 103 feet. Compared to the 

 mainland the Gault is of small thickness in the Island, 

 though the dark clay bands in the Sandrock mark the 

 oncoming of similar conditions. The fine sediment 

 forming the clay points to a further sinking of the sea 

 bed. In general, we find very few fossils in the Gault 

 in the Island, though it is very fossiliferous on the 

 mainland at Folkestone. North of Sandown Red Cliff 

 the Gault forms a gully, down which a footpath leads 

 to the shore. It is seen at the west of the Island in 

 Compton Bay, where in the lower part some fossil shells 

 may be found. 



The Upper Greensand is not very well named, as the 

 beds only partially consist of sandstone, in great part of 

 quite other materials. Some prefer to call the Lower 

 Greensand Vectian, from Vectis, the old name of the Isle 

 of Wight, and the Upper Greensand Selbornian, a name 

 generally adopted, because it forms a marked feature of 



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