138 Geological Society. 



I. On the N.E. of Folkstone, the chalk is succeeded by the equi- 

 valent of the Merstham Firedone, (or green sand,) which is there 

 however not more than fifteen or sixteen feet in thickness ; and this 

 is followed immediately by Gaidt. The Shan/din Sa)ids, (or lower 

 green sand,) which come next in succession, are composed of three 

 groups, which may be recognized also in the interior of the country. — 

 The first and uppermost consisting of sand, abounding in irregular 

 concretions of limestone and chert, sometimes disposed in courses 

 oblique to the general direction of the strata. And the top of this 

 formation, in the vicinity of Folkstone and Hy.the, forms an ex- 

 tensive plateau resembling that of the Blackdown range of hills in 

 Devonshire. — The second number of the group likevvise consists 

 chiefly of sand, but in some places so much mixed with clay, or 

 with oxide of iron, as to retain water ; and it is remarkable for the 

 great variation of its colour and consistency, — from the state of 

 loose bright yellow or ferruginous sand, to that of a dark greenish 

 tougli mass, like that of the clills of Shanklin and Black Gang- 

 chines, which correspond to it in geological situation. — The third 

 and lowest group of the Shanklin Sands abounds, near Folkstone, 

 much more in stone, the concretional beds being closer together 

 and more nearly continuous; and the fossils of this group, which 

 are very numerous, agree with those of the corresponding beds in 

 Sussex, the Isle of Wight, and Devonshire. The sections of the 

 Weald Clay, and Hastings Sands, being imperfectly displayed on 

 the coasts of Kent and Sussex, the author gives detailed lists of 

 the beds at Cowleaze-chine, &c., on the south coast of the Isle of 

 Wight, and on the shore of Swanage Bay in the Isle of Purbeck, 

 where these formations are fully disclosed ; referring for an account 

 of the geological relations of those tracts, to a paper published by 

 himself in the Annals of Philosophy for November 1824'*. 



II. The Lower Boulonnois may be described as constituting a 

 flattened dome of unequal curvature, surrounded on three sides by 

 an amphitheatre of chalk, which has been removed by denudation 

 from the whole of the interior: the lower strata having a very 

 gentle inclination where they emerge from beneath the chalk, but 

 rising from the sea at a much more considerable angle. From the 

 chalk dovvn to the Shanklin (or lower-green) sands, the strata of the 

 opposite coasts near Calais and Folkstone, precisely correspond ; 

 and the same beds may be traced beneath the chalk, almost without 

 interruption, around the whole of the denudation : the gnult 

 especially, being very distinctly disclosed in the vicinity of Har- 

 dinghen, where it is succeeded by the Bath oolite, and by the coal 

 formation. The next succeeding beds of the English coast, Weald- 

 clay and Hastings sands, (which it is remarkable, have not yet been 

 found in the interior of England,) appear to be wanting also in the 

 Boulonnois ; or, if they do exist there, to occupy a very small space. 

 But some traces of the lowest members of the group to which these 

 two strata belong, and which is remarkable from its containing 

 throughout the remains of freshwater shells, are visible on the 



* New Series, vol. viii. p. .365, &c. 



summit 



