o f Edinburgh , Session 1881 - 82 . 783 
they reached the slope of the hill, and would then find a resting 
place. 
This view is indicated by the following diagram, where A repre- 
sents a boulder in detritus, and B the same boulder when the 
detritus was nearly all removed from the valley : — 
In the Seventh Report of the Committee I suggested this explan- 
ation of the position of two boulders lying on the steep side of a 
valley near Oban ; and I now give these diagrams in further explan- 
ation of a difficulty which Professor Duns twice refers to in his 
notes.* 
Another point brought out by Professor Duns is the arrangement 
of boulders in approximate lines or rotes , of which several examples 
are given. Pie states that “ they appear in long lines , some times 
far apart, but there is no mistaking their place in the lines which 
are W.N.W. and E.S.E.” In another place he refers to ‘‘two rows 
of boulders being nearly direct west. The first block is grey granite, 
7x4x6 feet, angle of site to horizon 40°, the others are grey 
granites, porphyries, and mica schists, their larger axis being IST.jST. W. 
and E.S.E.” 
Keeping in view the trainees of boulders mentioned by Dr. IPeddle 
in last year’s Report, as seen by him in Rannoeh, it may be assumed 
that this arrangement of boulders is a feature requiring special 
attention, as probably indicative of the nature of the medium by 
which the boulders were brought to their present sites. I have no 
recollection of seeing in Switzerland, or hearing of boulders there, 
forming lines or rows after being projected from a glacier. But 
Arctic voyagers represent the sheets of ice formed along a rocky 
* That all or most of the valleys were filled originally with detritus is evident, 
from the account given in Dr. Heddle’s notes of a great bank of detritus found 
by him at a height of 2904 feet (page 35) ; and from the fact mentioned by 
Professor Duns, that one very large gneiss boulder (weighing about 100 tons) 
was found by him on a steep slope at a height of 1500 feet, resting mainly on 
three small rounded granite boulders (page 24). 
