126 
COLE: Pi\KALLEL EOADS OF GLEN GLOY. 
by the prevailing winds. Every bum has its delta, and ever}^ delta 
is on the east side of the burn. Examine the burns and deltas on 
the shore-line of Loch Lochy in operation now : exactly the same 
phenomena are apparent as in the parallel roads of Glen Gloy. So 
that I have come to this conclusion, that the roads were formed in a 
comparatively tranquil loch, not in an arm of the sea ; at a time when 
the ice sheet had passed away, and subsequent to any submarine 
depression ; formed, partly, by the grinding of shore ice, and, partly, 
by the accumulation of detritus brought down b}^ the existing burns, 
and left in a heap at the margin of the water ; that this detritus was 
constantly carried by the prevailing winds to the eastward of the 
burn to which it owed its origin, and then frequently spread out into 
a small level platform by the waves. Subsequently the loch was 
drained by the removal of the temporary barrier, either a moraine, 
or more probably a glacier, as so ably argued by Lyell, and the 
burns continued their downward course, cutting more deeply into 
the mountain sides, and carrying the debris to the level of the river. 
Meanwhile, the roads have naturally been the receptacle of loose 
stones and boulders, which, in places, have partially destroyed their 
symmetry. 
