1905-6.] Formation of certain Lakes in the Highlands. 109 
merged, as shown on the sketch map by the irregular and stony 
bottom at the north-eastern extremity of the 50-feet area. We 
suppose the barrier to be represented by the slope from the north- 
eastern end of the loch to the 100-feet contour. 
Let us now discuss why we consider Loch Muick to be a rock 
basin. 
1. If Loch Muick were not a rock basin, the frontal moraine 
which dams the drainage would be 200 feet high, a figure far too 
big for a small glacier, for we must not forget that this moraine 
was the last one deposited by the Muick glacier. The fact that 
we have never seen moraines 200 feet high, neither in actual 
glaciers nor at the head of glens, where one meets with moraines, 
