CHAP. VI.] CARBONIFEROUS PERIOD. 85 



of shallow and fresh-water conditions throughout the Scot- 

 tish Carboniferous series proves the neighbourhood of 

 land, and leads to the conclusion that the area of the 

 Devonian Lake Caledonia was converted at this period into 

 a land-locked gulf which stretched north-eastward into 

 continental land, and was only connected with the more 

 open sea by narrow channels between the mainland and the 

 islands above indicated. We may reasonably suppose that 

 many rivers emptied themselves into this gulf, especially 

 at its north-eastern end, and the nature of the deposits 

 indicates that the subsidence was at times more than 

 counterbalanced by the amount of material brought down 

 by the rivers, so that the eastern part of the gulf was some- 

 times silted up and converted into tracts of low swampy 

 land, enclosing large sheets of water, which were sometimes 

 fresh, sometimes brackish, and only occasionally invaded 

 by the sea. 



2. Geographical Restoration. 



The evidence for most of the coast-lines delineated on 

 Plate IV. has been amply discussed, and it only remains to 

 show reason for the lines to the east and south of England, 

 and to give some account of the conjectured extent of the 

 continent which lay to the north of the British Carboni- 

 ferous sea. 



The entire absence of Carboniferous rocks over the whole 

 of the Scandinavian peninsula, except the extreme south of 

 Sweden, renders it highly probable that this area formed 

 part of the northern continent, and was united to the 

 Scottish Highlands; the southern border of this land 

 seems to have crossed the centre of Denmark, and a pro- 

 longation of this line would strike the coast of Yorkshire. 

 Professor Hull suggests that it trended south-westward 

 and joined that of the land which lay over the midland 



