1916.] THE PLEISTOCENE PERIOD. 339 



an island of large size, being united to Herm. Alderney 

 with the reefs of the Casquets was another promontory of 

 France. The Schole Bank was an island. 



A lthough all this is quite certain, yet it is also true that 

 the sea found its way to all the low lands of these groupings 

 and constantly ate into their margins whenever its level rose. 

 When the level rose enough the sea washed the present 

 margins and covered large areas of these islands without 

 disconnecting them permanently. It was such rises of the sea 

 which cut our present coast-lines, in time retiring and leaving 

 the largei- tracks of low land again connected up. 



Thus the islands were shaped long before they were 

 finally separated and, indeed, would be very much larger even 

 now if the sea retired a very little. This I have dealt with 

 in former lectures so need not be elaborated further now. 

 (Mr. J. Sinel has shown this by maps as far as Jersey is 

 concerned in his recently published " Prehistoric Times and 

 Men of the Channel Islands." 



My object in introducing this here is to show that there 

 is no need to put down the whole of the lost land to erosion, 

 for change of sea-level is the chief cause of the encroachment. 

 That being understood, we can see that a sea-level high enough 

 to reach the present coasts would easily have shaped them. 



OAVES. 



I am not prepared to discuss the correctness of Dr. 

 Hoist's theory* of the oscillations of land, but it seems to me that 

 there is a tendency towards fixed points of arrest in the 

 processes of rise and fall of sea-level which, if admitted, will 

 go far in justifying the assumption that the islands were 

 carved to their present shape (less a margin of more recent 

 erosion) during late Pliocene times. In this part of my 

 argument I speak of two levels only, but these did not follow 

 each other as here shown, for other levels have to be placed in 

 order between them as will be treated of later on. These 

 points I term 



Points of Stability. 



They may be shown as follows : — 



12 3 4 5 6 

 50 feet — | o o 



/ | \ r \ * 



25 feet c — i — o o 



Tertiary. ' Pleistocene. 

 Nos. 1 and 2 are represented in the Bournemouth Beds. 

 * " The Ice Age in England," Dr. Nils Olaf Hoist. Geo. Mag., Sept., 1915. 



