D. MILNE HOME ON THE PARALLEL ROADS OF LOCHABER. 625 
Besides the lines to which I have adverted on Ben Chlinaig, Craig 
Dhu, and Ben Erin, and which may very probably be ascribed to sea agency, 
there are other appearances in the district which may have a similar origin. I 
allude to the extensive terraces and cliffs at lower levels, which certainly imply 
the presence and prevalence of large bodies of water, marine or lacustrine. 
Thus at and above the Roman Catholic Chapel in Glen Spean, there are 
terraces, apparently horizontal, at 717 feet, 558 feet, 458 feet, and 409 feet 
above the sea. On the hills between Spean River and Fort William, there are 
flats, as RoperT CHAMBERS points out (p. 94), at a height of about 391 
feet above the sea, consisting of gravel and sand, in stratified beds, which 
strongly betoken sea action. But these flats are manifestly quite different in 
character from the true Parallel Roads, and (in my view) afford not the slightest 
argument in favour of the opinion that these “‘ Roads” are marine. 
I turn now to the 
Ice Barrier Theory. 
-This theory is the one which has received the greatest number of sup- 
porters. First suggested by Acassiz, it has been accepted by Mr JAMEs 
THompson of Glasgow, Sir Cartes Lyeti, Mr Jamieson of Ellon, and Mr 
JoLLy of Inverness. 
1. Mr JAmigson’s paper is published at length in the “Journal of the London 
Geological Society” for 21st January 1863. Mr Jo.ty’s paper was read before 
the Edinburgh Geological Society on 17th April 1873, and an abstract of it is 
given in that Society’s “Transactions.” I had the pleasure of hearing the entire 
paper read, and I have since been kindly allowed an opportunity of reading 
and studying it. 
Both of these gentlemen suppose that glaciers were formed in three several 
places, viz.,—(1.) In the hills situated at the head of Loch Arkaig. (2.) On 
the north-east flank of Ben Nevis; and (3.) In the hollow between the hills 
now occupied by Loch Treig. 
With reference to the barrier which cr peed the Unichan district, petween 
the lowest shelf at Teindrish and the corresponding shelf at Corrychoilzie, Mr 
JAMIESON makes the following statement ;— 
“The extension of the lake was cut off here by a glacier issuing from Corry M‘Koin, and 
on the opposite side by the ice of Glen Arkaig, and the Great Glen, flowing over to near Tean- 
drish. This would close up the mouths of Glen Gluoy aud Glen Spean, and so long as the ice 
exceeded sufficiently the height of the water-sheds at the top of the glens, these cols would 
determine the level of the water in the lakes (p. 247). 
“But in Glen Roy there are three lines ;—and this barrier across the mouth of Glen Spean, 
Parallel Road, but several features which indicate sea action. There is an accumulation of debris 
from the rocks above, forming a sort of terrace. The terrace is not horizontal towards the valley. 
It slopes rapidly from the hill. 
