1905-6.] Formation of certain Lakes in the Highlands. 
Ill 
Loch Builg. 
Loch Builg (see fig. 2) lies in a short and narrow transverse 
valley, between Glen Avon and the head of the Gairn valley, at 
end, but it also contributes to the Dee, as water percolates through 
the moraine at the south end. As regards the formation of this 
loch, we believe that at the beginning of the later glaciation a 
lobe of ice passed northwards from the valley of the Gairn by Loch 
Builg, towards the Avon, which laid down a frontal moraine at its 
north end. Mr Hinxman, who mapped the area round Loch Builg, 
when consulted by Dr Horne, confirmed this view. How, to what 
is due the dam at the south end? After its regression, the 
glacier, increasing considerably, began again to creep down the 
mountain, now following the direction of the Gairn, laying down 
lateral moraines, of which one dammed the loch at the south end. 
