110 PALEOZOIC TIME. [CHAP. VII. 



balance of evidence is against the existence of any con- 

 necting strait, and in favour of the view that the Pennine 

 range then formed a continuous and lofty chain of hiHs 

 reaching from Derbyshire to the Scottish border, so that 

 the western Dyassic lake was entirely isolated from the 

 waters of the inland sea to the east. 



Neither can I see that there is any strong evidence for 

 the existence of the east and west barrier-ridge through 

 Cheshire, which is supposed by Professor Hull to have 

 divided the western area into two distinct lakes. The 

 differences between the Lancastrian and Salopian deposits 

 are really unimportant, and are quite compatible with 

 their having been formed in different parts of the same 

 lake. The width of the ridge, as shown on Professor 

 Hull's map, 1 is so small, that it is not likely to have been 

 a permanent barrier, but it may have been a subaqueous 

 ridge separating the lake into two basins, much as the 

 Mediterranean is divided into two basins by the ridge 

 between Sicily and Africa. 



This lake then appears to have extended from Warwick- 

 shire and the Malvern Hills to the Firth of Clyde, a 

 distance of 280 miles, with an extreme width of 100 miles, 

 so that it was about the size of the modern Lake Huron. 

 It spread over the counties of Warwick, Worcester, Staf- 

 ford, Salop, Cheshire, and Lancashire, and over the eastern 

 part of the Irish Sea. It encircled the Lake District, 

 which must have risen as a rocky island out of its waters ; 

 it covered the valley of the Eden and Solway Firth, and 

 arms of it ran up the valleys of the Nith and Annan, and 

 probably for some distance up the Firth of Clyde, while 

 westward a gulf extended into Ireland as far as Armagh 

 and Dungannon in Tyrone. How far it reached westward 

 and southward beyond Anglesey we have no means of 



1 Physical History of the British Isles," pi. riii. 



