GEOLOGICAL STRUCTURE OF THE ISLAND. 91 



the south-east of England ; and in the southern 

 division of the Isle of Wight, where not only the 

 lowermost cretaceous strata, but even the wealclen, 

 rise to the surface, in consequence of the highly 

 inclined position into which the central mass of 

 rocks has been thrown, the natural order of the 

 deposits is not inverted.* 



The Isle of Wight is of an irregular rhomboidal 

 form, being in length, from east to west, twenty- 

 three miles, and from north to south, in the widest 

 part, thirteen miles ; the circumference is between 

 seventy and eighty miles. Its surface comprises 

 about 105,000 acres, of which 75,000 acres are 

 under tillage, 20,000 acres are pasturage, and 

 10,000 acres unproductive heaths and commons. 

 The population is estimated at nearly 45,000. 



The map, PL XX, shows the range and extent 

 of the respective formations which lie beneath the 

 vegetable soil and superficial loam and gravel. The 

 section in the same plate represents a vertical cut 

 through the island, from Cowes on the north, to 

 the sea-shore beyond St. Catherine's down on the 

 south, and exhibits the relative position and direc- 



* The Underclitl" presents an apparent exception, for in some instances 

 masses of white chalk are seen covered with beds of firestnne, marl, and 

 gait ; hut these are merely portions of the cliffs that have fallen down in a 

 retroverted position from the encroachments of the sea in comparatively very 

 modern periods. 



E 



