80 Geological Society : — 



the "white gravels." These latter are distinctly hedded and seamed 

 with sand, and are more water-worn than the red gravels which pass 

 under them; thirdly, the white gravels are overlaid by "brick -earth," 

 which is somewhat variable in its characters. These, with their equi- 

 valents, are the glacial deposits of the district in question. The coast 

 sections, though very limited in extent, exhibit several important phe- 

 nomena illustrative of the history of these newer tertiary accumula- 

 tions. At Selsea, where the glacial deposits are about 2.5 feet thick, 

 the underlying eocene clay is seen, at extreme low water, to be per- 

 forated by a very large variety of Pholas crispata, and to be overlaid 

 by a deposit containing Ltttraria nigosa, Bullastra nurea. Tapes 

 decussate/, and Pecten polymorphus, contemporaneous with the Pho- 

 lades. Elsewhere brown clays, or local ferruginous gravels, cover 

 unconformably the eocene beds. The surface of the brown clay is 

 deeply eroded, and bears a yellowish clay, which contains large chalk 

 flints, and a great variety of pebbles and boulders of granitic, slaty, 

 and old fossiliferous rocks, such as are now found in the Cotentin and 

 the Channel Islands. One boulder of porphyritic granite measures 

 27 feet in circumference. A few sea shells {Littorina, &c.) occur in 

 the yellow day. This deposit the author regards as the equivalent 

 of the "white gravel" in its extension southwards, the gravel having 

 been littoral, and the clay with boulders a deposit formed in somewhat 

 deeperwater of this portion of the glacial sea. The coast-sections ex- 

 hibit the surface of the yellow clay as having been eroded and covered 

 by a variable deposit, sometimes gravelly and sometimes sandy, and 

 containing marine shells {Cardium edule, Ostrcea edulis, Turritella 

 terebra, &c.). This band contains also fragments of the old crystal- 

 line rocks obtained from the destruction of the miderlying yellow 

 clay. On the shelly and pebbly band lies the brick-earth, an unstra- 

 tified earthy clay deposit, with small fragments of flint and a few 

 pebbles, and with occasional silt-like patches. 



The particular subject of this paper was the occurrence of the 

 granitic arid slaty detritus in the yellow clay. These blocks are 

 especially numerous near Bracklesham, Selsea, and Pagham. The 

 author explained the difliculties that lie in the way of supposing that 

 they were derived from the Cornwall coast, or direct from the shores 

 of Brittany or the Channel Islands. His previous observations, 

 however, on the bed of the English Channel had prepared the way 

 for the explanation of the hypothesis he now advanced — of the 

 former existence of a land-barrier, composed of crystalline and 

 palaeozoic rocks, crossing from Brittany to the south-east of England, 

 and forming a gulf or bay open to the west. Into this bay the 

 marine fauna represented by the Pholas crispata and its associates 

 extended from the westward ; and in the hollow of the bay, at a 

 rather later period, coast ice brought the boulders from along the 

 old shore line, which is now represented by a sunken peak in mid- 

 channel and a shoal of granitic detritus. Alteration of level succeeded ; 

 and the partial destruction of the yellow clay deposit afl'orded the 

 overlying, pebble bed, and, in the author's opinion, the granitic blocks 

 found in the old raised beach at Brighton. Mr. Godwin Austen 



