248 PROCEEDINGS OP THE GEOLOGICAL SOCIETY. [Jan. 21, 



induced to do so, because some foreign savants have said on visiting 

 Scotland, " You have the glacier-mud, the transported boulders, the 

 roclies moutonnees, and the striated pebbles ; and your ice-scored and 

 polished rocks differ in no respect from those of the Alps. All these 

 we have seen and admit ; but where are your moraines ? " 



The glacier on issuing from the narrow gorge at the end of Loch 

 Treig dilated immensely, and, in doing so, the right flank of it had to 

 pass over a rough expanse of syenite forming a bit of low, rocky 

 ground in the middle of Glen Spcan ; but the surrounding hills are 

 of mica-schist with veins of porphyiy. This syenite has the pro- 

 perty of breaking up into large cubical blocks, often of immense size. 

 These have been swept before the advancing mass of ice, and have, 

 along with other debris, been disposed into long mounds, forming a 

 sort of semicircular arch, or great horse-shoe, with a sweep of some 

 miles. These concentric bands mark out most distinctly the former 

 edges of the glacier, as it shrunk from time to time with the return 

 of a milder climate. And it is instructive to observe how, in some 

 places, the ice has pushed this zone of blocks before it, uphill, off 

 the parent rock, and left them upon the mica-schist on the north side 

 of Glen Spean. 



The best view of these moraines is to be got by walking along 

 the footpath, or pony-road, that goes eastward from the entrance 

 to Loch Treig, along the base of the hill towards Badenoch. Having 

 proceeded about a mile or more along this tract, you will find your- 

 self at the summit-level of the road, where it crosses these moraines. 

 Here they start out from the hill into the wide low moor that occu- 

 pies the bottom of the valley, and from this point they may also be 

 traced slanting upwards across the slope of the hill towards the 

 gorge of Loch Treig ; showing how vastly the pent-up ice had dilated 

 on issuing from the narrow pass. Here the stuff consists of the 

 debris of the mica-schist with bits of porphyiy, but blocks of 

 syenite soon mingle with it, and become more and more plentiful. 

 Two chief lines of moraine now appear, stretching far out into the 

 plain with a gentle curve, and hold on with surprising regularity for 

 a long way. Outside of these, older hillocks of similar origin may 

 be traced for a considerable distance, showing that the glacier had 

 at_ one time been of much greater extent. But these two are so 

 perfect and well-defined as to indicate a long abiding of the ice at 

 their margin. The outer one is the largest, rising in some places 

 sixty or seventy feet above its base, and forming a narrow steep-sided 

 mound. Blocks of all sizes, up to fourteen feet in length, stick out of its 

 surface, mixed w T ith lesser debris of mica-schist and gneiss. The 

 inner moraine runs alongside of this one, in some places approaching 

 so closely as to mingle with it, in others receding 200 yards or more. 

 It contains less small debris, and is often composed wholly of large 

 blocks of syenite, many of them from five to ten feet, some of them 

 fifteen to twenty-five feet in length, which give it a very striking 

 appearance, forming a long pile of blocks like a ruined breakwater. 

 The biggest piece I saw was twenty-six feet in length ; it lay on the 

 top of some smaller fragments, and a little wounded lamb had taken 



