1862.] JAMIESON GLACIATION OF SCOTLAND. 177 



them, I found a few clearly marked glacial scores running horizon- 

 tally along, at a height a little below that of the lowest Glen Eoy 

 line, while the worn and rounded edges looked down the glen. The 

 amount of rock exposed and thus marked was but small ; and I should 

 have attached little importance to the latter circumstance had it not 

 been for the fact abeady mentioned of the rocks at the head of the 

 glen indicating the motion of ice coming up it, and passing out 

 to IN'.E. : for this would seem to show that Glen Roy had at one time 

 been filled with ice, which, unable to get out by way of Glen Spean, 

 owing to the vast accumulation in that direction, had been obliged 

 to discharge itself at the upper end into the more open outlet of the 

 Spey basin. When we consider the narrow character of the great 

 Caledonian Valley, bordered by lofty mountains and numerous side- 

 glens, and choked up as it must have been at its mouth by the jost- 

 ling of all these united ice-streams pressing out past Ben Nevis, and 

 recollect that proof has been adduced of Glen Spean being filled 

 with ice to the level of the top of Craig Dhu, which exceeds by 900 

 feet the summit-level of this pass into Strath Spey, the above singular 

 fact becomes less mysterious. 



§ 5. I have yet another example I should like to give, as further 

 illustrating and confirming what I have already advanced. 



In Argyleshire there is an arm of the sea called Loch Fyne, whose 

 upper branch stretches 25 miles from S.W. to N.E. far into the High- 

 lands. The scored and polished rocks all along its shores^ from In- 

 verary down to Loch Gilp, plainly indicate the former passage of ice 

 down the loch ; their rounded, worn sides facing the interior, and 

 the rough and more jagged outlines the sea. At Loch Gilp (which 

 is a small inlet off the west side of the lake), a low tract, forming the 

 bed of the Crinan Canal, runs across in an eastern direction to the 

 Sound of Jura. The rocks along this hollow are likewise much worn 

 and rounded, but chiefly on their eastern sides, and scored by glacial 

 furrows pointing W., parallel to the canal, and indicating the course 

 of an ice-current diverging from Loch Fyne. 



On looking at the map it will be seen that, if we produce the line 

 of Upper Loch Fyne in a south-west direction, it would run across 

 Knapdale into Jura Sound, near Loch Killisport. Now, I find the gla- 

 ciation of the rocks of Knapdale looks as if the stream of ice descend- 

 ing Upper Loch Fyne (so great had been its volume, and so immense 

 the vis a tergo impelling it onwards) had gone right out, over hill 

 and dale, into the Sound of Jura. Let any one who wishes to satisfy 

 himself of this examine first the course of the Crinan Canal, and he 

 will find the masses of syenite, in the hollow beside the Dunartry locks, 

 all worn and rounded on their south-eastern sides ; and searching 

 where the drift has recently been removed, he will find scores and 

 polish indicating a motion to N.W. Let him then ascend the hill- 

 slope from Cairnbaan, following the course of the ravine down 

 which the torrent came when the reservoirs burst, and he wiU see 

 the scores at the mouth of the stream running from E. 30° S. to W. 

 30° N. ; ascending the slope of the hiU, he will find the scores turn- 

 ing gradually to due E. and W., and, as he goes higher up, curving 



n2 



