698 
PROFESSOR PRESTWICH OR THE ORIGIN 
Table II. 
Approximate angles of inclination to the horizon of cross sections of the parallel 
roads of Glen Roy taken at various placesr 
From this it appears that the gradients of the “roads” vary from 1 foot in 11 
to 1 in 2, and that there are places where the angle of the “ roads ’ is as great as that 
of the slopes, hut this may be at places where the rock comes to the surface. 
As Macculloch remarked, the “ roads ” “ bear the resemblance of parallel layers 
applied in succession to the side of the hill,” and there is no instance (with the one 
exception of d, fig. 9—his No. 6) of a superior, and none at all of an inferior talus. 
This describes them with sufficient accuracy, although the parallelism is subject to 
some variation and is rarely exactly uniform above and below the “roads.” 
The importance of this feature has been overlooked by subsequent observers, with 
the exception of Sir John Lubbock,! who showed that with such a structure it was 
impossible for the “ roads ” to have been formed either by erosion or by the heaping up 
of the materials by wave or water action, in accordance with the theories hitherto held. 
In the one case he contends that a notch or sub-cliff, and in the other a prominent 
ledge would be formed. Nor can the notion of continuous deltas be admitted, as the 
shelves in that case ought to be broadest where rivulets came down the sides of the 
hills, or where the melting; snow brought down most detritus. But the “ roads ” 
exhibit no such irregularity of outline. 
Sir John Lubbock is of opinion that the parallelism of the slopes is due to a 
slight wave action on the loose materials which covered the hill sides, and which was 
accompanied by a re-adjustment of the debris at the original angle of repose ; but this 
* Two measurements of Glen Gluoy “road,” “on road fi’om Lieter Finlay A, W. side of Glen Gluoy 
River, sheet 112,” give respectively inclinations of 20° and 15°. 
t Quart. Jourii. Geol. Soc., vol. xxiv., p. 83, 1868. 
