144 Proceedings of Philosophical Societies. [Feb.' 



are given, and the succession of the strata, and the organic 

 remains which they contain fully described. The author first 

 treats of the chalk, and the sands and sandstone, usually called 

 green sand, as they occur between Lyme Regis and Axniouth ; 

 and then notices the same formations as they are exhibited in 

 the vicinity of Beer. 



From this examination it appears, that though there is a great 

 correspondence in the organic remains, considerable changes 

 take place in the mineral composition and characters of the beds 

 both of chalk and underlying sands, in short distances. Mr. 

 De la Beche considers it probable that the Beer-stone is the 

 equivalent of the Malm-rock of Western Sussex. 



A paper was also read, entitled, " Geological Sketch of Part 

 of the West of Sussex, and the NE of Hants, &c.; by R. I. 

 Murchison, Esq. FGS. &c." 



In this memoir, Mr. Murchison describes the geological rela- 

 tions, distribution, and characteristic fossils of the strata of that 

 part of the west of Sussex, which is bounded on the south by 

 the chalk escarpment of the South Downs ; and of that part of 

 Hampshire which is included by the Alton Chalk Hills. These 

 strata, commencing below the chalk, in a descending series, are, 

 1. Malm-rock, or Upper Green Sand ; 2. Gaull; 3. Ferruginous 

 Green Sand ; 4. Weald Clay. The Weald clay in the valley of 

 Harting Combe, may be regarded as the central nucleus of this 

 district, mantling round which, and extending up to either 

 chalk range^ the other formations are developed, in regular 

 succession : the breadth and boundaries of each are laid down 

 by the author on a coloured portion of the Ordnance map, to 

 which a section is annexed. 



The malm-rock of Western Sussex is identical with the stone 

 of Merstham : it is characterized by constituting terraces which 

 afford a rich soil favourable to wheat. It sometimes furnishes a 

 building stone, contains occasionally a calcareous blue chert, 

 and abounds in organic remains. 



The gault of this district has been cut through to the depth 

 of 120 feet, at Alice Holt, and iridescent Ammonites and other 

 fossils are found in it. This clay is marked by fertile water- 

 meadows, and the timber presenting a green belt clearly distin- 

 guishes it from the rich wheat land of the malm rock above, and 

 the arid expanse of the ferruginous green sand below it. 



Of this latter formation, the upper beds consist of pure white 

 sand, and in some places compact ironstone, and ironstone in 

 large cellular tubes are found. In the middle beds occurs a calca- 

 reo-siliceous grit, called Bargate stone ; in the lower, a siliceous 

 yellow building stone, containing casts of Ammonites, Terebra- 

 tulse, &c. The Weald clay includes in its middle beds the 

 compact Petworth marble, and in lower beds of clay in which 



