596 D. MILNE HOME ON THE PARALLEL ROADS OF LOCHABER. 
There are 3 or 4 valleys in Lochaber, to the North of Ben Nevis, each from 
10 to 15 miles in length, and having a depth of from 500 to 1000 feet, the sides 
of which are deeply notched by shelves called “ Parallel Roads”; so called 
probably, because being horizontal, they are parallel to one another, and consist 
of spaces, so broad and regular, that a cart might be driven on them.* 
In Glen Gluoy, whose mouth opens on Loch Lochy towards the West, there 
are two shelves, at a height, one of 1165, the other of 964 feet above the sea. 
In Glen Roy, whose mouth also opens towards the West, there are on each 
side of the Glen, for a considerable part of the valley, 3 shelves, at these respec- 
tive heights above the sea (beginning with the highest) —1149, 1068, and 856 feet. 
In Glen Spean, which in its lower part joins Glen Roy, there is only one 
well-defined shelf, 856 feet above the sea. It is a continuation of the lowest 
in Glen Roy. 
Dr Maccuttocu was too cautious to offer a decided opinion regarding the 
origin of the shelves. He gave a minute and correct account of the pheno- 
menon :—but he advanced no positive explanation, confessing his inability to 
give any. He only suggested general views, and farther inquiry. 
Sir Tuomas Dick LAupER thought that the Roads had been formed by lakes, 
but he was much at a loss to account for the removal of the Barriers by which 
the lakes had been retained. 
Mr Darwyy, in his paper, thought the Barrier difficulty so great, that he 
deemed no other explanation possible, than that the ‘‘ Roads” were sea-beaches. 
His theory was adopted by the late Ropert CHAMBERS, Professor Nicot, Mr 
Watson, and others. 
Professor Acassiz and Dr BuckLaAnp accepted the theory of Lakes, and 
suggested that the Lakes had been dammed up by Glaciers; a view taken 
by a majority of subsequent inquirers, and in particular by Sir CHARLES LYELL, 
Mr JAmiEson of Ellon, and Mr Jo.ty of Inverness. 
III. Such being the nature of the problem and the various attempts to solve 
it, let me now briefly indicate the view which I have taken. It is much the 
same as that explained in my former Memoir: But I expect now to be able to 
rest it on a wider basis of facts, and to support it on stronger grounds. 
I concur with the great majority of observers, in atributing the formation of 
the shelves to Lakes. My reasons are these,— 
Ist. In three of the Glens, the existence of an old River Channel has been 
ascertained and traced, by which in each Glen, the surplus Waters of the Lakes 
were discharged. 
*In Glen Gluoy (as Sir Tuomas Dick Lauper states) the highest shelf has a width of 100 yards. 
In Glen Spean Shelf 4, above Inverlair House, has a width of 20'yards. (See fig. 17, p. 51.) In 
Glen Gilaster, on the side next Craig Dhu, this same shelf has a width of nearly 100 yards, as is 
shown on the Ordnance Survey 6-inch Map. 


