Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/348

 in no instance did I perceive the marks of an inferior one. But the profiles now referred to, which were selected among the most remarkable ones, will represent these several circumstances better than they can be described by words.

With regard to their structure I can only say, that it does not appear to me calculated to throw light upon any system respecting their origin. When they are found on those faces of hills where the rubbish is sharp, they consist of sharp materials; where it consists of transported materials, they are formed of rounded gravel and sand. Whatever hypothesis of their formation may be adopted, it is evident that this circumstance can throw no light on it; as, whether they are the effects of nature or of art, they must have been formed in and of the materials in which they exist.

Having thus described Glen Roy itself with the lines for which it is distinguished, and pursued its connection with the neighbouring vallies, it is necessary to extend our views, and to trace its connection with the sea.

The glen itself opens by a wide mouth, as I before said, into the great valley which stretches between the northern and western sea, and which is the seat of the Caledonian canal. This opening is so gradual that its breadth cannot be defined, but it may be conceived to vary from five to seven miles. The whole of this space is uneven and hilly, consisting of rocky elevations and alluvial deposits. The Spean flowing through it and falling into the Lochy forms one deep section, but no other water courses are found in it, either direct or lateral; such at least as exist are of very insignificant dimensions. On applying the spirit level to a great many points through this wide space they were all found inferior to the lowest line of Glen Roy, with one or two trifling exceptions. The opening of Glen