XCVl PROCEEDINGS OF THE GEOLOGICAL SOCIETY . 



into the phsenomena of this class of deposits has for some years been 

 popular amongst ur>, as might have been expected when we consider 

 how much the correct appreciation of everything connected with the 

 Tertiary formations has been promoted by the labours of Sir C. Lyell. 

 During the present session we have had a paper from Mr. Godwin- 

 Austen on the Newer Tertiary Deposits of the Sussex Coast, in which 

 the author follows up a class of inquiry he had before entered 

 upon in respect to the coasts of Cornwall, Devon, the Channel 

 Islands, and the Cotentin, namely the determination of a series of 

 oscillations in the level of the land, of comparatively recent date. 

 As preparatory to the consideration of this highly interesting ques- 

 tion, Mr. Austen first notices the condition of the English and 

 French coasts, and points out that the irregular wear consequent 

 here, as everywhere, on the unequal resisting power of the rocks 

 exposed to the action of the sea, has produced the various bays or 

 indentations, such for example as Weymouth Bay and Yarmouth 

 Bay, though the wear was probably accelerated or retarded by 

 either a depression or an elevation of the coast, tending to remove 

 from the action of the sea a more easily disintegrated stratum, or to 

 bring up a less destructible one. Such wear as this depends upon 

 the impulsive action of the waves, and wherever it can be traced 

 inland, proves that the sea must at one time have had access to the 

 inland indentations, just as it now has to the coast-bay, a remarkable 

 instance of which I have pointed out in the north of Ireland, where 

 such indentations occur in a chalk escarpment now 200 feet above 

 the level of the sea, the inland bays thus formed having been filled 

 up with the mud of the pliocene epoch before the period of that 

 final elevation which abstracted them from the action of the sea. 

 The same is the case in respect to the coast described by Mr. Austen ; 

 the sea is still making an impression upon the softer portion of the 

 rocks, and nothing can be more variable in destructibility than the 

 chalk ; but it is also threatening to break through the barriers which 

 keep it from storming the bays or indentations which were formed 

 by the former action of its waves. 



If, instead of prospectively regarding the results of this continued 

 action, we were to trace it backwards, there would be no great diffi- 

 culty in mentally tracing the cliffs as they receded from the present 

 inner land on both sides until they met and barred across the channel, 

 as supposed by Mr. Austen, without even the intervention of any 

 material elevation or subsidence. On such a supposition, the action 

 of the waves of the western ocean on the one side, and of those of the 

 northern on the other, must have rapidly advanced the work of de- 

 struction, until the formation of the channel by the final rupture of the 

 barrier, when the action would still continue, but be varied in its direc- 

 tion. Taking up now the elements upon which Mr. Austen founds his 

 theory of change of level, — he first points out that the summit-levels 

 of the hills extending from Devonshire are capped by a detritus, the 

 upper portion of which is characterized by rounded pebbles of pri- 

 mary rocks — white quartz, porphyry, and granite, and this fact alone 

 necessarily implies that the tidal or transporting agency of the sea 



