PRESTWICH BRIGHTON BEACH. 215 



out the shale beneath so deeply that the great fallen blocks are lost 

 in the abyss. Where the body of water is small in the American 

 Fall, the edge has only receded a few yards (where most eroded), 

 during the time that the Canadian Fall has receded from the north 

 corner of Goat Island to the innermost curve of the Horse-shoe Fall. 



On the Westward Extension of the Old Eaised Beach of Brighton; 



and on the Extent of the Sea-bed of the same Period. 



By Joseph Prestwich, Esq., F.E.S., F.G.S. 



[Eead May 26, 1858.] 



This raised beach, with its curious old sea- cliff brought to light again 

 in the modem cliffs at Kemp Town, was first made known by the 

 late Dr. ManteU*. Mr. Dixon f afterwards showed that beds of the 

 same age extended to Shoreham and Broadwater, near Worthing ; 

 whilst Mr. Godwin- Austen J has more recently described, on the 

 coast between Bognor and Bracklesham, two thin marine beds of 

 Kewer Tertiary age, the uppermost of which he considers synchronous 

 with the raised beach of Brighton §. The exact range westward and 

 inland of this old beach, or of the sea- deposits of the same age, has 

 not, however, yet been determined. With a view to assist this in- 

 quiry, I beg to lay before the Society the facts having reference to 

 it which I have collected during the last few years, whilst exami- 

 ning the Older Tertiary strata and the drift-beds of this district, — the 

 result, however, more particularly of two excursions made with the 

 special view of tracing, if possible, the line of old cliff along the 

 southern base of the South Downs between Brighton and Ports- 

 mouth. On the present occasion I do not propose to touch upon the 

 question of the drift ||, beyond describing such portions of it as are 

 exhibited in conjunction with the older sea-bed. I may merely 

 observe that the drift which has passed over this district has so 

 swamped and hidden even its later geological features, that in a 

 distance of thirty-seven miles I could not find a single place where 

 an old line of cliff, such as that at Kemp Town, could be recognized 

 by any irregularity of surface, although I have, in several instances, 

 traced the sea-bed and shingle of that period to within a few hundred 

 feet of the chalk-hills. There is, in fact, nothing in the present fea- 

 tures of the country to indicate the exact place of the old coast-line. 

 At Brighton the line of old chalk- cliff ranges probably nearly 

 parallel to, and not far distant from, the present shore, receding 

 rather further at Hove, but nowhere, between Brighton and Shore- 

 ham, extending above half a mile from the present coast. Between 

 Hove and Shoreham a bed of sand and shingle with recent shells, 



* The Fossils of the South Downs, &c., p. 277. 

 t Dixon's Geology and Fossils of Sussex, p. 40. 

 \ Quart. Journ. Geol. Soc. vol. xiii. p. 62. 



§ See also the observations of Sir JR. Murchison on this beach and on the 

 overlying drift, Quart. Journ. Geol. Soc. vol. vii. p. 364r-372. 



II See the papers by Sir E., Murchison and Mr. Godwin- Austen on this subject. 



