50 ON THE PARALLEL ROADS 



south-west of these points, since not the slightest vestige of 

 Shelf 4th, has been discovered any where in that direction. 

 But as, in the case of Loch Roy, this also actually appears on an 

 examination of the ground, to be by far the most natural and 

 probable position for the barrier of Loch Spean, since the se- 

 micircular range of little hills, or what I have called the eleva- 

 ted moor, which exactly follows the supposed semicircular 

 line I have sketched out, rises even now, nearly, and I believe 

 in some places entirely, to the level of Shelf 4th, so that if the 

 ravine at Highbridge were closed up, and the deficiencies in the 

 elevated moor supplied, the perfect barrier for the confine- 

 ment of the water of Loch Spean, would be reproduced. I 

 say the perfect barrier, — because I believe tliat the lake had 

 no outlet here at all, but that this was its upper end, and that 

 as in the other cases, the former loch and the present valley 

 have changed extremities. The primary Loch Spean, then,^ 

 must have stretched from a point a little above Highbridge, 

 all the way to the summit-level of the bottom of the Pass of 

 Muckul, a distance of not less than twenty-four miles. There 

 the level of Shelf 4th sufficiently shows, that the surface of the 

 lake had such a relation to the ground at that end of it, that 

 it must have discharged the River Spean (or Little Spey^ 

 for such is the interpretation of its name), through the Pass 

 of Muckul, by a straight and natural course, carrying it 

 to direct union with the Spey, which at that time brought 

 along with it the Gluoy and the Roy, in addition to the 

 waters supplied by its present source. Whilst matters were 

 in this situation, the river Pattaig must have entered near 

 the eastern end of the lake, to be immediately afterwards dis- 

 charged by it through the Pass, along with the rest of the wa- 

 ter passing from Loch Spean, and in a course much more na- 

 tural to it than that in which it now runs. Loch Treig must 

 then have been a great southern limb of Loch Spean, and the 



tops 



