382 Glacial Epoch in Britain. 



bably as thick as that in the north of Greenland in the 

 present day. During this time all the Highland moun- 

 tains were literally buried in ice, which, partly flowing 

 eastward, joined a vast ice-sheet coming westerly and 

 southerly from Scandinavia. Jn another direction a 

 thick sheet of the same Highland ice pressed southward 

 into the valley of the Tay, where a low stratum of the 

 glacier passed eastward to the sea, while the remainder 

 pressed up the slopes and across the summits of the Ochil 

 Hills, and on to the valley of the Forth, where it found 

 a vent for a further outflow to the east, at a time 

 when the Bass Rock, Fidra Island, Inch Keith, Inch 

 Colon, and all the other beautiful islands of the Firth 

 of Forth, lay as mere roches moutonnees, buried so deep 

 under glacier-ice that it overflowed the eastern part 

 of the Lammermuirs and spread southward into 

 Northumberland. Some of these islands still retain 

 their ice-worn surfaces, while others, such as the Bass 

 and Fidra, have become scarred and cliffy by the action 

 of weather and the sea (figs. 80 and 81). Another part 

 of the great glacier-ice passed west across the Hebrides, 

 and southerly into the Firth of Clyde, where, passing 

 over Bute, and smothering and smoothing those large 

 mammillations the Cumbraes, it was reinforced by 

 the snows of Arran, and buried that c craggy ocean 

 pyramid,' Ailsa Craig. All the southern Highlands, 

 from Fast Castle on the east to Wigtonshire on the west 

 coast, were also covered with glacier ice, together with 

 Northumberland, Durham, and the beautiful dales of 

 Yorkshire, scooped out of the Carboniferous series of 

 rocks. Cumberland too was buried in ice, part of which 

 crossed the vale of Eden and over the hills beyond, 

 carrying detritus to the eastern shore of England. So 

 great was this ice-sheet that, joining with the ice- 



