238 



THE WONDERS OF GEOLOGY. 



Lect, III. 



spread over the whole area of the New Forest and the 

 Trough of Poole, being flanked by the chalk on the north, 

 north-east, and north-west, and open to the sea on the 

 south. The Isle of Wight, though now separated from the 

 main land, is a disrupted mass of the formations of the 

 south-east of England ; the chalk basin having been broken 

 up, and the cretaceous strata, with the superimposed sands, 

 clays, and gravel, thrown in many instances into a vertical 

 position. This phenomenon is strikingly displayed at the 

 north-west extremity of the island, at Alum Bay, and in 

 the eastern, at Culver Cliff and Whitecliff Bay. 



26. Alum bay. — Alum Bay, so called from the alum, 

 formerly extracted from the decomposing pyrites with 

 which the clay abounds, is well known to the visitors of 

 the Isle of Wight. This sketch (Lign. 36) conveys a 

 general outline of the bay ; a, represents the vertical chalk ; 

 b, b, the tertiary strata, consisting of sands and clays of an 



Lign. 36. — Alum bay, Isle of Wight; from the west. 

 a, Chalk strata, nearly vertical, b, b, Vertical Tertiary strata. 



infinite variety of colour. The appearance of these cliffs is 

 thus graphically described by Mr. Webster, whose memoir 



