GO 
THE PARALLEL ROADS OF 
ganic life upon these terraces. If they were 
ancient sea-beaches, we should expect to find 
upon them the remains of marine animals, 
shells, Crustacea, and the like. All the ex¬ 
planations given to lessen the significance of 
this absence of organic remains are futile. 
Again, why should the lower terrace alone he 
continued into the eastern end of the valley of 
Glen Spean, while there are no terraces at all 
in its western part, since both must have been 
as fully open to the sea as Glen Roy valley 
itself ? This seemed the more inexplicable 
since all the terraces exist on the valley-wall 
opposite the outlet of Glen Roy, showing that 
this sheet of water, wherever it came from, 
filled the valley itself and the space between it 
and the southern wall of Glen Spean, but failed 
to spread, on either side of that space, into the 
eastern and western extension of Glen Spean. 
It is evident, that, at the time the water filled 
Glen Roy, some obstruction blocked the valley 
of Glen Spean, both to the east and west, 
leaving, however, that space in the centre free 
into which Glen Roy opens, while, by the time 
the water had sunk to the level of the lowest 
terrace, one of these barriers, that to the east. 
