228 Mr. Webster on the Strata lying over the Chalk, 



are not subdivided into distinct beds, are parts of extreme com- 

 pactness, so as to acquire a porcellanous character. Other parts 

 contain masses of loose chalky matter, most of which are of a 

 roundish form -, and among these also are many beds of a cal- 

 careous matter, extremely dense, and much resembling those 

 incrustations that have been formed by deposition from water on the 

 walls of ancient buildings in Italy. 



Through all these last strata are veins, frequently several inches 

 in thickness, of very pure carbonate of lime, which is crystal- 

 lized, frequently in a radiated form. 



This stratum may be seen in many parts of the Isle of Wight, 

 north of the middle range of chalk hills. On the western coast it 

 does not extend farther than Totland bay, but occurs again at 

 Warden point, forming the summit of the cliff. 



Numerous blocks of it lie loose in the soil in many parts about 

 Cowes, Binstead, and Bembridge. But in the neighbourhood of 

 Calbourne, and between that place and Thorley, several quarries 

 are opened in it, and afford an excellent stone. The fossil shells 

 are here larger than I have observed them in any other part, the 

 planorbes being full two inches in diameter, and the cyclostomse 

 nearly as large. The rocks at Bembridge ledge and Whitecliff 

 bay, on the east side of the island, must also be referred to this 

 formation. 



It appears therefore to have originally extended over the whole 

 of the northern half of the island j but I have not yet been able 

 to find it on this side of the water, and it is still uncertain whether 

 it ever existed here, or whether it has disappeared amidst the last 

 revolutions to which the surface of the earth has been subjected. 



This formation may be considered as the latest in this country 

 which we have as yet been able to detect : and of all those above 



