263 



On some New Points in British Geology. By Professor 

 Edward Forbes, President of the Geological Society. 

 Communicated by the Author. 



Not many years ago it used to be said that the geology of 

 England was done, and yet the best investigated localities are 

 constantly affording fresh discoveries. When the lecturer 

 last year exhibited Captain Ibbetson's beautiful and accurate 

 model of Whitecliff Bay in the Isle of Wight, in illustration 

 of his views respecting the distribution of species in time, he 

 had not the slightest suspicion that this particular locality, so 

 often and apparently so thoroughly explored, could yield new 

 results and new interpretations. Nevertheless, having had 

 occasion, at the suggestion of Sir Henry De la Beche, to ex- 

 amine the tertiary strata of the Isle of Wight for the purposes 

 of the Geological Survey of Great Britain, this very bay of 

 Whitecliff proved to be a rich source of novel geological infor- 

 mation. Moreover, a great portion of the Isle of Wight, on 

 further examination, turned out to belong to a division of the 

 older tertiaries that had never been demonstrated to exist 

 within the British Islands. As a general statement of these 

 results and of their bearings may be more intelligible to non- 

 professional lovers of geology than the detailed memoirs about 

 to be published on the subject, Professor Forbes has taken 

 this opportunity of communicating them to the Members of 

 the Royal Institution. 



The Isle of Wight is divided into two portions by a great 

 chalk ridge running east and west. This is the ridge of ver- 

 tical chalk beds. To the north of it, the country is composed 

 of tertiary, to the south, of older strata, as far down in the 

 geological scale as the Wealden. The lower Greensand or 

 Neocomian beds occupy the greater part of the surface of the 

 southern division, and fresh-water tertiaries that of the north- 

 ern. At Alum Bay on the west, and Whitecliff Bay on the 

 east, the ends of the older tertiary strata, as they rise above 

 the chalk, are seen truncated and upturned, being all affected 

 by the movement which caused the verticality of the chalk. 

 These tertiaries constitute the following groups, successively 



