220 Some remarkable Boulders in the Isle of Man. 



Professor James Geikie* developed this idea, and 

 showed that the striae upon glaciated surfaces in Ayrshire, 

 and down to the Mull of Galloway, showed a deflection 

 coastwise, as they were traced down from the hills, and 

 that they furnished clear proof of the flow of ice from thQ 

 Firth of Clyde into the Irish Sea. 



This evidence was perfect so far as such evidence could 

 be, but there has been lacking the testimony of boulders, 

 which I now supply. It must be distinctly understood 

 that I do not express any opinion whatever on the vexed 

 question of the origin of lake-basins, but merely point out 

 the corroboration of Mr. Home and Professor Geikie's 

 opinion that ice came from the Clyde into the Irish Sea. 



There is a further point to which I would allude, viz : — • 

 the altitudes attained by these boulders. In the Isle of 

 Man, foreign boulders are traceable only to a very moderate 

 height, and the highest point to which I have traced the 

 Ailsa Craig rock is at the dam of the Ramsey Waterworks, 

 in Ballure Glen. The altitude reached on Moel Tryfan is 

 about 1,350 feet, whereas the total height of Ailsa Craig is 

 only 1,097 feet, so that, assuming that the Riebeckite rock 

 attains to the actual summit, it must have undergone an 

 uplift of 250 feet in its transit to Moel Tryfan. 



* Great Ice Age (2nd ed.) p. 294. 



