LOWEE GREENS AND. 57 



This brings us to the coast section at RedcllfF, the section of 

 which was given on p, 35. The Carstone here, as everywhere, 

 passes up into the Gault, and shows at this locality a greater 

 thickness than in any other part of the Isle of Wight, namely, 

 72 feet 9 inches, A small fault, previously alluded to, is clearly 

 shown in the Carstone, and in some of the beds below ir. Such 

 phosphatic concretions as occur consist of cemented masses of grit, 

 and seem to have been formed in place. The whole rock is 

 markedly ferruginous. 



From Niton and Blackgang to Shanklin and Bonchurch. 



We will now trace the course of the Carstone around the 

 southern hills of the Island, proceeding as before from west to 

 east. The exposures about the Undercliff near Blackgang are 

 numerous and easily accessible. The Carstone forms the brow 

 of a shelf in the cliff, which is occupied by the Gault, or more 

 usually by the debris of Upper Greensaud and Chalk that has 

 slid down over the Gault. This brow may be traced continuously 

 from Chale to the Chalybeate Spring. It reappears above 

 Knowles, and near the foot of the cliff below Niton presents its 

 most eastern exposiu-e. Still further east the southerly dip is 

 believed to carry the Carstone down to the level of the beach, but 

 no rock ap[)ears in situ to determine the point. 



The following section was noted above the Chalybeate 

 Spring : — 



Ft. In. 



Gault ; blue clay passing down. 



"Brown grit, interbedded witb grey clay, and 

 containing phospliatic nodules in the upper 

 part - - - - -80 



Blue clay - - - - - 3 



Reddish-brown grit, very red in parts - 1 



Line of small quartz pebbles with rolled 

 phosphatic nodules up to 2 inches in 

 diameter - - - - - 2 



Sand-rock Series (for details, see p. 31). 



Carstone <| 



12 2 



In the cliff below Niton we find the following details: — 



Ft. In. 



Gault ; blue clay passing down . 



TBrown grit ==.--- 



I Clay- parting - - - - - 



Carstone <( Brown grit witb phosphatic nooules - 



I Brown sand and clay . - . 



[_Pebbly and ferruginous band 

 Sand-rock Series ; grey sand with seams of blue clay, 

 seen to 41 ft. 



