262 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 4, 



The famous mammaliferous limestones of Binstead and Seafield 

 have always been considered equivalents of some of the Headon beds, 

 usually as equal to the Lower freshwater limestones. 



Respecting the foreign equivalents of the Headon Hill series (above 

 the Headon sands), there have been conflicting opinions. 



The oldest view, originally suggested by Webster, was, that they 

 represent the whole series of tertiaries above the Calcaire grossier in 

 the Paris basin. 



M. d'Archiac (1849) regarded them as representing his fifth 

 group, that of the Calcaire silicieux only, and as possibly represented 

 by the Sables de Diest in Belgium. 



M. Dumont (18.51) identified them with his Tongrieu system of 

 Belgium, the Limburg beds of Sir Charles Lyell. 



M. Hebert (1852) maintained that the Venus-bed of Colwell Bay 

 was higher in the series than the strata of Headon Hill, and was the 

 true representative of the Gres de Fontainebleau and Limburg beds. 

 The Hordwell freshwaters he compared with those of Montmartre, 

 and the Barton marine beds with the Gres de Beauchamp. 



A very different view of the relative position of the Headon beds 

 was taken by Mr. Prestwich, who, in 1847, argued that they belonged 

 to a much lower place in the series, and were the equivalents of the 

 upper portion of the Calcaire grossier. 



A statement of the conclusions to which I have come from my own 

 observations will serve to show the points of difference between them 

 and those arrived at by previous investigators. 



The section at Headon Hill includes only a portion of the fluvio- 

 marine strata of the Isle of Wight, and the greater part of the sur- 

 face of the island north of the chalk ridge is occupied by beds higher 

 in geological position than any seen in Headon. 



The section at Whitecliff Bay includes not only all the fluvio-ma- 

 rine series at Headon Hill, but also a thickness of nearly 1 00 feet of 

 strata higher than any seen in that locality. 



The section at Colwell Bay is composed entirely of beds present in 

 Headon Hill. 



Hempstead Hill, east of Yarmouth, contains between one and two 

 hundred feet of beds higher than those concluding the series at 

 Whitecliff Bay, Equivalents of these beds seem to be present at 

 Parkhurst, but nowhere else in the island. 



The Limestones of Binstead, Seafield, Colborne, and Sconce be- 

 long to the same bed with the Limestone of Bembridge Ledge, which 

 is not the equivalent of any of the conspicuous limestones of Headon, 

 but is there represented by a calcareous marl, mostly concealed by 

 grass and lying immediately under the newer tertiary gravel that 

 crowns the hill. 



The greater part of the surface occupied by fluvio-marine beds in 

 the Isle of Wight is formed of the marls that lie above the limestone 

 at Bembridge and Whitecliff (see fig. 1). 



