238 Reports and Proceedings — Geological Society of London. 



position of growth. Four peat-beds occur in this silt, at 4, 11, 20, 

 and 85 feet below Ordnance datum respectively. The uppermost 

 peat contains a seam of shell-marl, partly composed of the shells of 

 ostracoda and partly of Bythinia, Limncea, etc. The second is a 

 mass of matted sedges. The third is a land-surface, and in places 

 consists almost wholly of timber with the stools and roots in situ. 

 The fourth is also an old land-surface, as is proved not only by the 

 presence of roots in place beneath it, but by numerous land-shells. 

 A fragment of a polished flint-celt was found by Mr. Storrie 

 imbedded in the lower part of the uppermost peat. 



By a comparison with the existing maritime marshes of the 

 neighbourhood, it is shown that the fourth peat indicates a sub- 

 sidence of not less than 55 feet. 



The sea encroached upon the area in consequence of this sub- 

 sidence. It entered by the lowest of three low cols in the southern 

 water-parting of the Cadoxton river, thus isolating the portion of 

 land now known as Barry Island. A slight further movement 

 would have converted the water-parting into a chain of islands. 



2. " On a Phosphatic Chalk with Holaster planus at Lewes." By 

 A. Strahan, Esq., M.A., F.G.S. With an Appendix on the Ostracoda 

 and Foraminifera by F. Chapman, Esq., F.B.M.S. (Communicated 

 by permission of the Director-General of H.M. Geological Survey.) 



This rock, which occurs at the base of the Upper Chalk, at the 

 horizon of the Chalk Bock, does not exceed 1-| foot in thickness, and 

 persists for a few yards only. In composition and microscopic 

 character it presents a close analogy to the Taplow phosphatic 

 deposit, which, however, occurs at the top of the Upper Chalk. 

 Like it, it consists of brown phosphatic grains imbedded in a white 

 chalky matrix. The grains include a large number of pellets, 

 attributable to small fish, phosphatized foraminifera, chips of bone, 

 etc. Fish-teeth also occur in abundance. 



To complete the resemblance, the Lewes deposit rests on a floor 

 of hard nodular chalk, beneath which is a white chalk traversed by 

 irregular branching pipes filled with the brown variety. Such 

 " floors " are attributed to concretionary action ensuing upon a pause 

 in the sedimentation. The piped chalk is compai'ed with the 

 structure known as Spongia parudoxica. 



It is concluded that phosphatized deposits may occur at any 

 horizon in the Chalk ; that the phosphatization is due to small fishes, 

 attracted by an. unusual abundance of food ; that they are shallow- 

 water deposits, and associated with a pause or change in the 

 sedimentation. 



Mr. Chapman furnishes a list of 42 species and varieties of 

 Foraminifera and 6 species of Ostracoda. The former indicate a 

 deeper water origin than do those of the Taplow Chalk. He notes 

 the occurrence for the first time in this country of Gypsina Coetcs, 

 Marrson. 



3. " On the Classi6cation of the Strata between the Kimeridgian 

 and the Aptian." By Dr. A. P. Pavlow, Professor of Geology in 

 the University of Moscow, For.Corr. G.S. 



