1863.] JAMIES0X-— PARALLEL ROADS OF GLEN ROY. 249 



refuge in the recess beneath it. "Within this moraine there is a wide 

 smooth space, like a bay, almost destitute of boulders for a con- 

 siderable distance, and overgrown with a green swampy turf; show- 

 ing that the glacier had made a considerable retreat without halting 

 long enough anywhere to leave much debris. 



These two moraines, after being traced for a mile or so out into 

 the moor, become less regular, and gradually merge into the boulder- 

 covered surface. Their curve seems to indicate that the glacier had 

 crossed the Spean near a place called Gorstan. On the north side of 

 the valley two crescent-like zones, evidently a continuation of those 

 I have been describing, stretch eastward from the spur of Craig Dhu 

 to near Ben Caoran (pronounced Ben Hourin, meaning the llowan- 

 tree Hill). We might liken the two curving mounds to a double 

 rainbow, and the outer hillocks to the supernumerary bows. 



It seems to me that these moraines, together with the ice-worn 

 gorge, afford about as good evidence of the former existence of the 

 Glen Trcig glacier as a fossil skeleton does of the former existence 

 of the living animal. 



The position of the outer hillocks shows that the ice must have 

 pressed against the hills on the north side of Glen Spean, so as 

 to have blocked up the outlet for the water by the Glen Glaster Col, 

 and boulders of the syenite are numerous in the hollow beside it. 

 The inner ones in like manner demonstrate that gradual shrinking 

 of the ice which the theory requires. 



These parallel moraines are as fine a sight to a geologist as the 

 Parallel Roads themselves, and no one who goes there should omit 

 seeing them. Those at the mouth of the Larig Leachach Glen arc 

 also well worth a visit. 



There are no such fine moraines at the mouth of Glen Spean ; but 

 the greater part of the extensive moor called Unichan, or Aonachan, 

 is overspread with what appears to be glacial debris, partly modified 

 by failing into the water of the old lake. The same is the case high 

 up on the shoulder of the ridge all round from Tiendrish towards 

 Loch Lochy. Large boulders arc scanty, although one is met with 

 here and there ; the stuff being mostly a rubbish of mica-schist — a 

 rock which furnishes a smaller debris with few great blocks. 



The character of a moraine depends, of course, upon the rocks that 

 furnish it, and the striking features of those I have described are in 

 a great measure due to the accident of the glacier having to pass 

 over the rough tract of syenite. Much also depends upon the moraine 

 being formed (to borrow a chemical phrase) in the dry way ; for when 

 the stuff from the glacier falls into a lake or pool, its features assimi- 

 late to those of an aqueous deposit — a circumstance that has misled 

 many good geologists. 



The immense accumulations of gravel about Inverlaire and the 

 mouth of Loch Treig seem to partake of this mixed character, being 

 probably the terminal moraine-matter of the glaciers of Glen Trcig 

 and Corry Laire when they protruded into the margin of the lake. 



At Inverlaire, and around the large rocky knoll called Tom-na- 

 fersit, they have been finely terraced by the action of the water when 



