1855.] AUSTEN — SUSSEX TERTIARIES. 5 



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 clay. 



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 deeper 

 water of this portion of the glacial sea. 



The coast-sections exhibit 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. Turrit ella terebra, &c.). This band contains also 

 fragments of the old crystalline rocks, obtained from the destruction 

 of the underlying yellow clay. 



On the shelly and pebbly band lies the brick-earth, an unstratified 

 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 and slaty detritus in the yellow clay. These blocks are 

 especially numerous near Bracklesham, Selsea, and Pagham. The 

 author explained the difficulties 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 observa- 

 tions, 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 palaeo- 

 zoic 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 afforded the overlying pebble-bed, and, in the 

 author's opinion, the granitic blocks found in the old raised beach 

 at Brighton. 



Mr. Godwin-Austen thinks it probable that the superficial brick- 

 earth of the district under notice was formed in a land-locked lagoon, 

 subject to periodical freezing; and that the "elephant-bed" at 

 Brighton is one of its many and variable equivalents (in this case 

 probably subaerial). 



The brick-earth area has been subsequently encroached upon by 

 the estuaries of Pagham, Portsmouth, &c. ; and the successive oscil- 

 lations in the level of the land are evidenced in the estuarine depo- 

 sits and submerged forests of Pagham, Bracklesham, Portsmouth, 

 &c. 



With regard to the latest moven^ents, the author's observations 



