17 



TUESDAY, NOVEMBER 13th, 1900. 



®l]£ ^ttmnt ^tntljts of Srigljton anft 

 tlj^ir ^irrastoptral Contents, 



BY 



Mk. FRED. CHAPMAN, A.L.S., F.R.M.S. 



RAISED Beaches are among the most interesting phenomena 

 with which the geologist has to deal. That they have been 

 subjected to elevation above the present sea-level is clear from 

 their relative position to modern sea-beaches, to which they are 

 similar in structure ; often consisting of shingle or subangular and 

 rounded fragments of rock, which have been rolled and worn 

 down by the tides, and accumulated in a bank above mean tide 

 by the superior forces of spring tides and rough weather. 



In a bay of considerable extent we may find at one end the 

 piled-up shingle due to concentration of wave action against a 

 steep shore ; and at the other, where the shore has a gentler 

 slope, finer material rapidly passing into fine sand which is 

 often ripple-marked, owing to the currents abating in force. A 

 section through a bed of this fine sand will sometimes show 

 false-bedding, and sometimes horizontal stratification. We also 

 find the conditions of a fine sandy area indicating deeper water. 



The ancient sea-beach to be seen at Brighton, east and west 

 of the town, was first brought under notice by Dr. Mantell, who 

 described the sections seen in the cliff near Kemp Town (see 

 "Fossils of the South Downs" and "Medals of Creation"). 

 The extension of this ancient beach to Shoreham and Worthing 

 was recorded by Frederick Dixon, whilst Godwin Austin 

 described a similar beach between Bognor and Bracklesham. A 

 section taken along a line from the shore at Brighton to the 

 chalk downs will show the Raised Beach forming a level 

 platform or terrace until it ends against the foot of the chalk 

 hills. This beach is in turn covered by a rather irregular layer 

 of rubble-drift deposit. The hall in which we are now assembled 

 is actually situated upon the Raised Beach. 



Standing on the shore at Black Rock we can see the bed of 

 rounded shingle pebbles with gigantic sarsen stones at the base, 



