314 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



conspicuous in Black-Gang Chine, between the two sand-rock beds 

 47 and 49. The upper part is of a dark grey or blackish hue, with 

 a somewhat slaty texture. About 30 feet from the bottom is a range 

 of ferruginous nodules. The lower part is a dull greenish and grey 

 coarse iron-shot mass, traversed by numerous rifts, and apparently 

 containing much pyrites. 



XVI. Various Sands and Clays. — Nos. 49 to 55. 



The series from the top of 48 to the bottom of the gault occupies 

 a thickness of more than 1 30 feet, throughout which fossils are here 

 extremely rare. Within the fissure of Black-Gang Chine it is not 

 easy to subdivide or to measure these beds, and my numbers in the 

 Table, obtained without levelling, are no doubt short of the true thick- 

 ness. The greater part consists of sand scarcely concreted, which 

 breaks down easily under the hammer, and in some places is intimately 

 mixed with dark argillaceous or carbonized matter. Some of these 

 sand beds also contain green particles in small proportion. 



The mineralogical character of these upper strata here differs from 

 that of their representatives in Kent and Surrey, where the upper 

 sands contain chert in great abundance ; and near Folkstone some 

 of the fossils also are siliceous, like those of Black Down in Devonshire. 



The upper beds of this section are continued eastward of Black- 

 Gang Chine, beneath the gault, at the same slight inclination. They 

 are thence concealed beneath the undercliff on the east of Bocken 

 End, and do not reappear, so far as I am informed, between that 

 point and Bonchurch Cove. 



In the sandy clay at the very top of the section in Black-Gang 

 Chine I found specimens of three or four species, among which a 

 Panopcea and a Venus could be distinguished. And casts of a Sola- 

 rium and of an Ammonite are mentioned by Captain Ibbetson and 

 Mr. Forbes as occurring in the same situation*. These, it will be 

 observed, are all genera known to occur in the gault immediately 

 above. — No other fossils have come to my knowledge. 



Superficial gravel and sand. — Throughout this section, the top of 

 the cliffs is coated with transported matter, abounding in fragments 

 of chalk flints; frequently 10 feet, and sometimes even 20 feet in 

 thickness. The bottom of this deposit is so like the sand of the 

 strata beneath, that it is often not easy to distinguish them. This 

 lowest part, on the heights at Walpen, is clearly stratified, and de- 

 serves examination. 



Gault. — The bluish clay above the lower greensand at Black-Gang 

 Chine, and thence eastward, has afforded in the upper part few fossils, 

 or none ; but very near the bottom it contains Ammonites and other 

 characteristic shells, which, with the position and thickness of the 

 beds containing them, leave no doubt of the perfect correspondence 

 of this deposit with the gault of other parts of England and of 

 France. Among the species is Ammonites Raulinianus (recognized 

 by Mr. Sowerby), which has not before been obtained in the English 



* Geol. Journal, vol. i. p. 191. 



