OF THE PARALLEL ROADS OF LOCHABER. 
671 
pass is broad and flat, but, at the same time, be notices a mark horizontally running 
along the side of the hill, with a distinct line of stones left by the water. 
When the lake stood at the level of the second “road” in Glen Roy, Mr. Milne 
Home has shown that it must have drained over the col at the top of Glen Glaster 
and the river have flowmd along its summit level and down the declivity to the Rough 
Burn. Here, again, Mr. Nicol points out that, had such been the case, the river 
should, with the duration ascribed to the lake on the theory of the “ roads ” being the 
result of prolonged shore-action, have cut for itself a deep and long gorge down the 
pass, just as the drainage of the same hydrographic basin has effected in the present 
river channel. But the summit level of the col is flat and unindented, and thence 
to the Rough Burn there is only the narrow and unimportant channel of the present 
small rivulet, and no trace of the existence of a large stream. Nor does he see any 
evidence of river action in the pass of Makoul, though he allows that a river might 
have flowed through that narrow ravine without leaving any very deep trace behind. 
The lines of shingle often occurring in these passes he considers to be old sea beaches, 
and he, like Chambers, concluded that the passes were old straits.'"" 
Other observers have put a different construction on these indications of water 
action. Of the Makoul Pass, Mr. Jamieson says that the crags on either side have 
been ice-worn, but that below a certain level these “ markings are effaced and the rock 
worn into smooth sinuous curves,” forming water-worn ledges strewed with “ well- 
rounded balls of stone as large as cocoa-nuts,” while in the sheltered bends or lee-side 
of the crags are large heaps of pebbles, affording “good proof that a strong brawling 
current had long gone out here;+ while Mr. Milne Home j speaks in general terms 
of an old river course on the Glen Gluoy Pass, remarking that it is 40 yards wide, and 
that the rocks are much worn. He notices similar features in the Glen Roy Pass. In 
the Glen Glaster Pass he found no sand or gravel, but numerous spherical boulders. 
His opinion is, however, that in all these passes there are appearances as of the former 
passage of much greater volumes of water than can be accounted for by the present 
streams—an opinion in which I agree. 
Neither he nor Mr. Jamieson make any mention of narrow and definite channels 
such as would have resulted from the long-maintained action of these rivers. Had 
any such existed they could hardly have escaped their notice and argument. 
§ 4. The Terraces of Macculloch ; the Deltas of Chambers and Jamieson. 
In the absence of river channels, Mr. Jamieson has relied on evidence of another 
class, viz. : that of the so-called deltas, in proof of the long duration of the Lochaber 
lakes. Amongst the most important of these mounds is the one in Glen Turret, which 
he ascribes to the action of the small stream of the Turret, remarking, however, that it 
“ is more than twice as big as that of the Roy,” which should have had “ much the 
* ‘Ancient Sea Margins,’ pp. 95 and 111. t Quart. Journ. Geol. Soc., vol. xix. p. 243. 
X Trans. Roy. Soc. Edinb., vol. xxvii., p. 597. 
4 R 
MDCCCLXXIX, 
