144 MAN AND THE GLACIAL PERIOD. 



therefore we might expect that an ice-sheet of very large 

 dimensions would result from this combination of fa- 

 vouring conditions. The Irish ice-sheet appears to have 

 moved outward from about the centre of the island, but 

 the main flow was probably concentrated through the 

 gaps in the encircling mountains. 



" Galloway. — The great range of granite mountains in 

 the southwestern corner of Scotland seems to have given 

 origin to an immense mass of ice which moved in the main 

 to the southward, and there are good grounds for the 

 belief that the whole ice-drainage of the area, even that 

 which gathered on the northern side of the water-shed, 

 ultimately found its way into the Irish Sea basin and 

 came down coastwise and across the low grounds of the 

 Einns of Galloway, being pushed down by the press of 

 Highland ice which entered the Firth of Clyde. It is a 

 noteworthy fact that marine shells occur in the drift in 

 the course taken by the ice coming on to the extremity of 

 Galloway from the Clyde. 



" The Lake District. — A radial flow of ice took place 

 down the valleys from about the centre of the Cumbrian 

 hill-plexus, but movement to the eastward was at first for- 

 bidden by the great rampart of the Cross Fell escar|)ment, 

 which stretches like a wall along the eastern side of the 

 Vale of Eden. 



"During the time when the Cumbrian glaciers had 

 unobstructed access to the Solway Frith, to the Irish Sea, 

 and to Morecambe Bay, the dispersal of boulders of char- 

 acteristic local rocks would follow the ordinary drainage- 

 lines ; but, as will be shown later, a state of affairs super- 

 vened in the Irish Sea which resulted, in many cases, in a 

 complete reversal of the ice-flow. 



" The Pennine Chain was the source of glaciers of ma- 

 jestic dimensions upon both its flanks in the region north 

 of Skipton, but to the southward of that breach in the chain 

 (see map) no evidence is obtainable of any local glaciers. 



