TI1K I'l.KISTofKNK SHI: IKS 617 



e.i\ered liy .-in.\v and ice which moved outward from tin- principal 

 r-sheds ; tin- ice-Meld- nt' tin- Central aii'l Northern Highland! 

 forming a OOnflun1 ire-sheet \\hich spread out in all direct ions a ml 

 de-reiided into the neighbouring seas (see Fig. 202). 



The south of Scotland formed another centre of dispersion, the 

 ire llo\ving off itw uplands, moving chiefly in western, southern, and 

 ea-tern directions, becau.-e tree movement to the north was blocked 

 l>v I lie more northern ice-sheet. 



There are, however, exceptions to the coincidence between the 

 direction of the stri;e and that of the main valleys; thus the dis- 

 trict known as Knapdale in Argyllshire, which rises to 700 or 800 

 feet above the sea, is glaciated obliquely from north-east to south- 

 west, as if the ice had filled up the valley of Loch Fyne, and had 

 (lowed over the ridge to the Sound of Jura. There seems also to 

 have lieen a time when the ice from the Perthshire highlands went 

 across the Ochil Hills, some of which reach a height of 2300 feet, 

 and these are important facts to remember when the mode of 

 glaciation is considered. 



In the north of Ireland again the Glacial striation is not of a 

 simple radiating character. According to Mr. J. R. Kilroe, the 

 strue can be resolved into two sets, the one set having a general 

 direction from east-north-east to west-south-west across the whole 

 area with local variations to west and south-west in Mayo and 

 Gahvay, while another set show lines of movement northward, 

 southward, and south-eastward. These facts he interprets to mean 

 that there was first a local snow-field covering all the high ground 

 between Mayo and Antrim and shedding its ice both to the north 

 and the south ; but that at the time of maximum glaciation the 

 Irish ice was so dominated by that flowing off the Scottish 

 Highlands that it was forced to move westward (see Fig. 202). 



The Lake district and the Welsh mountains were also independ- 

 ent centres, and the glaciers of the former seem to have maintained 

 their radiating onward movement throughout the whole of the 

 Glacial epoch, but their terminal parts wen- merged into the ice 

 flowing off the south-west of Scotland. In Wales the stria; also 

 have a general radiating arrangement from two centres, the 

 Snowdonian and Merioneth mountains forming one, the Plynlimmon 

 Group and the highlands of Central Wales forming the other. 

 .Movement to the north and north-west was, however, blocked by 

 the northern ice, so that Anglesey is glaciated from north-east to 

 south-west, Denbigh, Flint, and South Lancashire from north-west 

 to south-east. Consequently the ice of North Wales moved chiefly 

 to the east and south-east, and boulders from the Arenig mountain.- 

 have been carried eastward into Shropshire and Staffordshire. 



