THE OLIGOCENE 65 



Cowes and Ryde, and from Sea View to St. Helens. In 

 Whitecliff Bay they are not well seen, occurring in over- 

 grown slopes. They consist mostly of red and green clays. 

 A band of cream-yellow limestone a foot thick is the most 

 conspicuous feature. The fossils resemble those from 

 the Headon beds, but are much less plentiful. The marls 

 seem to have been mostly deposited in lagoons of brackish 

 water, which at the present day are favourite places for 

 turtles and alligators, and of these many remains are 

 found in the Osborne beds. The beds are specially noted 

 for the shoals of small fish, Diplomystus vectensis (Clupea), 

 first observed by Mr. G. W. Colenutt, F.G.S., and 

 prawns found in them, and also remains of plants. 

 The beds that appear in the neighbourhood of Sea 

 View and St. Helens are divided into Nettlestone Grits 

 and St. Helen's Sands, the former containing a freestone 

 8 feet thick. 



Above these beds lies the Bembridge limestone, which 

 is so conspicuous in Whitecliff Bay, and forms Bembridge 

 Ledge. On the north shore of the Island the strata rise 

 slightly on the northern side of the syncline. There are 

 also minor undulations in an east and west direction. 

 The result is to bring up the Bembridge limestone at 

 various points along the north shore, where it forms 

 conspicuous ledges Hamstead Ledge at the mouth of 

 the Newtown river, ledges in Thorness Bay, and Gurnard 

 Ledge. In Whitecliff Bay the limestone, about 25 feet 

 thick, forms the conspicuous reef called Bembridge Ledge. 

 The Bembridge limestone consists of two or more bands 

 of limestone with intercalated clays. It is usually whiter 

 than the Headon limestones, and the fossils occur as casts, 

 the shells being sometimes replaced by calc-spar. The 

 limestone has been much used as a building stone for 

 centuries, not only in the Island, but for buildings on the 

 mainland. The most famous quarries were those near 

 Binstead, from which Quarr, the site of the great Abbey, 



