HEADON HILL AND COLWELL BAY IN THE ISLE OF WIGHT. 95 



being almost made up of Limnoia sholls and their debris, that it 

 seems most convenient to include it in the Lower freshwater group ; 

 and it makes an especially good boundary. 



The beds which follow next below the LimnaBa-limostone at this 

 spot are whity -brown or yellowish sands, and sand rock with 

 Paludina and Potamomya in layers ; 8^- feet are seen ; this is all 

 that is exposed of the Lower Headon here. At this spot all the 

 ground below is tumble or undercliff ; and for a more complete 

 section of the Lower Headon in the present state of the cliffs we 

 shall do best to take the one exposed in Warden Cliff and under 

 Totland Bay Hotel, where the fresh road-cuttings to the New Pier 

 have been of service to us. 



"We consider that we have already sufficiently proved the identity 

 of this lower limestone in Headon Hill with the How-Ledge bed of 

 "Warden Cliff ; but if any objection be raised that its relations to 

 certain specified bands in the (Middle Headon) Marine series being 

 found identical in both localities is not conclusive — even though it 

 has been shown that no other marine bed exists in Headon Hill — 

 we have further means at our command. There are, however, only 

 two beds in Headon Hill with which the How-Ledge bed could be 

 continuous : viz. either it is the same as the thick Upper Headon 

 limestone (which we consider impossible, as the beds both above and 

 below would then just be reversed, viz. freshwater above and marine 

 below, instead of vice versa), or it must be identical with the one to 

 which we assign it. It is possible, however, to settle the point by 

 ocular demonstration *. Though the How-Ledge limestone is 

 denuded from the top of the curve between Weston and Widdick 

 Chines, some of the lower beds are traceable the whole way. Ac- 

 cordingly we can join on the section in Headon Hill to that in 

 Warden Cliff. We account thus for a continuous section of beds 

 from the lowest seen beds of the Lower Headon, through the Middle 

 and Upper Headon of Colwell Bay, to the Bemb ridge Limestone on 

 the north, and again from the same base of the Lower Headon, 

 through the succeeding Lower Headon beds in the cliffs between 

 Weston and Widdick Chines, to the sand below the How-Ledge 

 limestone at the N.E. corner of Headon Hill, and thence up to the 

 Bembridge limestone on the south ; and we find that the section is 

 identical in both eases. There is only one Marine (Middle Headon) 

 series, lying between two freshwater series, the Lower and Upper 

 Headon. 



Of course, all this has been done before by the Geological Survey, 

 and our work is nothing but a confirmation of results already suffi- 

 ciently established by E. Porbes and Mr. Bristow. 



On our horizontal section of the coast we have endeavoured to 

 represent the position of the beds in the cliffs and the extent to which 



* We are indebted to the Kev. O. Fisher, F.Gr.S., who specially visited Tot- 

 land Bay this autumn, for the information that the Venus-bed is found in the 

 Totland-Bay brickyard some little way above and behind the top of the cliff 

 between the chines. He points out that since this is the only part where it is 

 missing from the cliff, it is the link needed to prove that the bed is continuous 

 all through. 



