CHAP. V.] DEVONIAN PERIOD. 63 



separate basin, which has been named Lake Fanad by 

 Professor Hull. 



We may now glance at the succession of events in the 

 south of England. Here, in the sea which occupied the space 

 between the northern part of France and the Bristol 

 channel, there had been continuous deposition of sediment 

 throughout the Devonian period. After the first elevation 

 at the close of Silurian times, this southern area does not 

 seem to have been affected by the upheaval which was in pro- 

 gress to the northward, and indeed it may have occupied a 

 trough of compensating depression. The western part of it 

 was raised into land, however, after the formation of the 

 Glengariff Grits, all the south of Ireland probably being 

 land during the formation of the Middle Devonian rocks. 



According to Professor G-osselet, the Devonians of the 

 Boulonnais and the Ardennes were deposited in a narrow 

 strait connecting the wider seas of the Westphalian and 

 the Anglo-French areas. 1 Along the northern side of the 

 Devonian tract from Boulogne to Namur the Lower Devo- 

 nian is absent, and the base of the Eif elien division consists 

 of conglomerate and sandstone. It is highly probable that 

 the land thus indicated was connected with that which lay 

 over the centre and east of England. 



Parts of Brittany and Normandy seem also to have been 

 land, and Professor de Lapparent thinks that they formed 

 an island, the limits of which were very nearly the same as 

 those of the present massif of Cambrian and Ordovician 

 rocks. Inlets of the Lower Devonian sea penetrated the 

 district near Brest, in Basse Loire, on the frontiers of 

 Maine and from the Normandy side ; but whether it sank 

 beneath the sea of the Middle and Upper Devonian epochs 

 is not known, as the strata of these stages occur only to 

 the south in Basse Loire! 



1 " Esquisse geologique da nord de la France," p. 60; but the evidence 

 for the southern shore of this strait is inconclusive. 



