30 (iKOLOGY OF THE TSLE OF WIGHT. 



Group XIV., the Ferruginous lio.ds of Blacki^aiig Chine, forms 

 the upward liiiiit of the io.-siliferous beds of tlie Lower Green- 

 sand. The beds ajipeai" nhove the shore at a ])oint 600 yards 

 north-west of Rockeu End, and form a vertical fiot to the cliff 

 as far as Black gang Chine. Here the undercliff formed by 

 Groups XII. and XIII. commences, and the harder beds of Group 

 XIV., listing slowly in the cliff, form a step between this undercliff 

 and a similar feature formed above by Grtmp XV. The cascade 

 in the lower part of Blackgang Chine, which was ascertained by 

 Fitton to be 91 feet in height, is caused by the comparative hard- 

 ness of the ferruginous bands of Group XIV. This group crops 

 out in the top of the cliff on the south side of Walpen Chine, and 

 strikes thence in a bold escarpment through Pyle, Corve, and 

 Kingston. 



The details of the group are given by Dr. Fitton as below : — 



Ferruginous Bands of Blackgang Chine. 



Ferruginous concretions, immediately above the cascade 

 Brown and yellow sand " " ' " . 



Ferruginous concretions, with many vacant moulds of fossils, 



most abundant near Walpen High-Cliff - 

 Sand, with fossils - " . ' 



Ferruginous sand-rock, with fossils - - - 



The species found in this group can be identified in several 

 cases with those of the Perna Bed, at the very bottom of the 

 Lower Greensand. Among them may be named PanopcBa 

 plicata, Sow., P. neocomiensis, D'Orb., Corhula striatula, Sow., 

 Thetis minor, Sow., Trigonia caudata, Ag., Pinna rohinaldina, 

 D'Orb., &e. 



The next overlying bed, forming the lower member of Fitton's 

 Group XV., is a great mass of clay, between 35 and 40 feet thick. 

 It occupies the shore for a distance of 350 yards, first rising into 

 sight near a waterfall 200 yards north of Rocken End. It forms 

 a step in the cliff as far as Blackgang Chine, where it widens 

 out into an undercliff. The most convenient place for examining 

 it will be found from 500 to 600 yards west of Cliff Terrace, near 

 the top of the cliff, where the shale of which the bed largely consists 

 has been cut back by wind ;md rain into a broad shelf, entirely 

 bare of vegetation. This bed forms the top of the great division 

 of the Lower Greensand, which we have named the Ferruginouy 

 Sands. 



Tlie Sand-rock Series. 



This series, like the other beds of the Lower Greensand, attains 

 its oreatest development in the southern part of the Island, its 

 thickness being 186 feet by Fitton's measurements, or 208 by 

 those of Ibbetson and Forbes, while at Compton Bay it amounted 

 to 81^ feet only. Here also it contains in their typical form 

 tliose beds of slightly coherent white or yellow quartz sand, 



