92 GEOLOGY OF THE ISLE OF WIGHT. 



tion of the principal deposits ; these are further 

 exemplified by the instructive diagram, PL VII, 

 p. 94. 



By a reference to the map it will be seen that 

 the eocene strata which were deposited on the 

 chalk when the latter was in a horizontal position 

 (lign. 2, p. 74), form the northern division of the 

 island ; this tract of country is coloured pink. 



The other portion (coloured blue) is almost en- 

 tirely composed of the different members of the 

 cretaceous system. The white-chalk forms a range 

 of downs from the eastern to the western extre- 

 mity, and is flanked on the south by the lower 

 beds of this formation. These are succeeded by 

 another group of chalk-hills, that expands into a 

 broad and lofty promontory, in some parts be- 

 tween 800 and 900 feet high, crested by St. Cathe- 

 rine's, Boniface, and Shanklin downs. On the 

 southern escarpment of this chain the inferior 

 deposits of the cretaceous system reappear, and 

 fallen masses of these rocks form the irregular 

 line of terraces which constitute the Undercliff. 

 The downs on the southern coast are separated 

 from those inland by an anticlinal axis which 

 extends through this part of the Island, and is 

 produced by the upheaval of the firestone, gait, 

 and greensand. Tins is shown by the section 



