726 PROFESSOR PRESTWICH ON THE PARALLEL ROADS OF LOCHABER. 
of the ice-striae and the position of the glaciated surfaces are mostly taken from pre¬ 
vious memoirs, with few additions by the author ; but the bearings of the former are 
given in most cases in conformity with his own views. 
The distribution of the moraine detritus is shown only in the area visited by the 
author, and the map gives therefore a very partial indication of its extent. It will 
need a detailed survey to give a complete view of its distribution. West of Spean 
Bridge, also, it is only laid down very generally, without pretending to exact defi¬ 
nition, the object being merely to show its large accumulation outside the barrier on 
the site of the old ice-dam. 
The size of the several lakes may easily be estimated by prolonging the lines of the 
“ Parallel Roads ” from the main barriers to the coll or pass at the head of each 
respective glen or valley. 
