40 GEOLOGT OF THE ISLE OF WIGHT. 



CHAPTER IV. 



LOWE R GREENS AND— a^n^m«e</. 

 Inland Sections. 



(1.) Along the Central Downs. 



The Atherfield Clay. 



No section of any importance occurs in this division away from 

 the coast, and the tracing of a base-line has consequently been 

 a matter of some difficulty The clue to the position of the 

 boundary is provided by the topographical feature and change of 

 soil produced by the Ferruginous Sands above. 



The Ferruginous Sands and Sand-rock Series. 



These two groups will be conveniently taken together in de- 

 scription. As previously remarked, they pass one into the other. 

 Commencing our description on the west, we find the Ferruginous 

 Sands rising into a characteristic escarpment, slightly lower than 

 the Chalk Downs, which runs eastward from Compton Bay on 

 the north side of Brook, Mottistone, and Brixton. The higlier 

 part of the ridge is formed by the iron-sand which comes down 

 to the beach on the west side of Compton Chine. The more 

 massive iron-sand which forms the cliff on the east side of 

 Compton Chine crops out in the southern slope of the hill, and 

 gives rise to the terrace of deep-red sand on which Brook Church 

 stands. The position of the Sand-rock Series is marked by the 

 abundance of white sand in the soil. 



At Mottistone a ravine has been cut through the Ferruginous 

 Sands. The top of the Atheffield Clay seems to occur at the 

 Church. The clay is overlain by a great thickness of ferruginous 

 clayey sands with a marked bed of brown iron-sand, which seems 

 to be the same as that on the east side of Compton Chine. 

 At the top of the ravine the following descending section may 

 be traced in beds which form the passage between the Sand-rock 

 Series and the Ferruginous Sands : — 



Near the Long Sto?ic, 3Iottistonc. 



Feet. 

 White sand, about - - - - - 20 



Ironstone ...... i 



Grey and " sooty " silt and sand . - .15 



Grey silt . - - . . .6 



Red clay, grit, and sand . - - - 10 



Ferruginous grit - - - - - 2 



Dark " sooty " silt . - - - - 12 



Ferruginous grits, &c. - - - - - — 



654 



