19 



pears from the traces of lithophagi in the cliffs between Rome and 

 Palermo, much above the present sea-level, and from other colla- 

 teral testimony. 



March 16. — W. P. Brigstock, Esq. of Stokes Hill, near Guildford, 

 in Surrey ; Robert Ingham, Esq. of the Inner Temple, London ; 

 James Overbury Anstie, Esq. of Devizes, Wilts ; and James Back- 

 well, Esq. of Charlotte Street, Blackfriars, London, — were elected 

 Fellows of the Society. 



A paper was read, "On the Geology of the vicinity of Pulborough, 

 Sussex 5 " by P. J. Martin, Esq. 



The author's object is to give a detailed account of the district 

 on the north of the South Downs, extending from about Petworth 

 on the west, to Steyning and the Adur on the east, and inter- 

 vening between the portions of Sussex described by Mr. Mantell 

 and Mr. Murchison. The structure of this tract agrees, in general, 

 with part of the adjoining district on the west ; but two of the for- 

 mations are here subdivided into natural groups, which the author 

 conceives ought to be distinguished ; the following being the series in 

 a descending order, which has come under his observation : — 1. Chalk. 

 2. Firestone, — including upper greensand, and Malm-rock. 3. Gault. 

 4. Shanklin sand, — including, as subdivisions, ferruginous sand, and 

 lower greensand and sandstone. 5. Weald clay. 



The portion of the Firestone, which the author denominates Up- 

 per Greensand, may be traced distinctly as a thin bed at the foot of 

 the chalk hills from Sutton to Washington, and is best exposed at 

 the entrance of the Arundel defile, resting upon the Malm-rock, — an 

 argillaceous limestone which extends into terraces in some places 

 50 feet thick and half a mile in breadth. The Gault is probably 

 not more than 60 feet in its greatest thickness : it is widest on the 

 E. of Sutton, and thence eastward varies in width from a few hun- 

 dred yards to a quarter of a mile. The upper, or ferruginous, por- 

 tion of the Shanklin sand, occupies the broadest space between the 

 chalk and the weald, and is from one to three miles in width, its 

 northern boundary forming a very distinct escarpment. The sur- 

 face of these sands is distinguished by its barrenness; they vary 

 much in consistency and colour, and the lower beds especially, are 

 pervaded by seams of clay, and abound in a stone consisting of 

 coarse, siliceous sand cemented by oxyd of iron. The lower divi- 

 sion of this formation (green sandstone) has in some portions 

 a strong external resemblance to the stratum immediately be- 

 neath the chalk. It constitutes a fertile arable country, and affords 

 pure and copious springs. The upper part contains thick layers 

 and nodules of limestone, chert, and clay resembling fuller's earth. 

 The lower affords a compact building-stone, which has long been 

 quarried at Pulborough : but further west, these beds pass into 

 chert. This stratum has obviously suffered great disturbance ; and 

 one of its natural chasms, forming the valley of Greenhurst, and 

 about 4 miles in length, points towards the outlet of the Arun, and 

 might probably be taken advantage of to connect that river with 

 the Adur. The demarcation between the lower part of the Weald 



