1869.] NICOL — PAEALLEL EOADS. 287 



of the flood was swept away ; huge rocks were torn up and were 

 floated along, just as pine timber would have been floated in an 

 ordinary waterway. One of these stones so floated weighs upwards 

 of thirty tons, and is in dimensions not unlike one of the largest 

 stones at 8tonehenge. Hundreds of tons of smaller stones were 

 torn up and swept along. Of the first mills encountered by the 

 flood, not a vestige remains to show where they stood — the build- 

 ings, site, and subsoil (rock and shale) having been scooped out 

 and swept away, as also the ground for a considerable distance 

 around" 



If such results followed on the sudden drainage of a small reser- 

 voir, can we believe that the water in the upper Glen-Eoy lake, to 

 a greater depth and covering nearly a hundred times the extent of 

 surface, all passed away down a steep and by no means wide valley, 

 without leaving behind any trace of its passage ? 



The next point of supposed lake-drainage is the Pass of Maccoul, 

 between Loch Laggan and the Spey. This pass is a narrow ravine 

 with a flat bottom and a very shght declivity from the watershed 

 either to Loch Laggan or the Spey. A river might thus have 

 flowed through it without leaving any very deep trace behind. It 

 is also much encumbered with peat, which hides and obscures the 

 outline of the ground on which it rests. Hence though I observed 

 no indications of an old river in this locality, I put less value on the 

 negative evidence thus furnished. On the other hand it is curious 

 that the river Puttaig, which falls into the pass from the south-west, 

 and which would more naturally have flowed on to the Spe^^, turns 

 sharply round and runs to Loch Laggan. Had a river from the lake 

 flowed formerly in the other direction, we should have expected the 

 present river to have continued its old course and not to have taken 

 the reverse. The present channel, though not deep, is still well 

 marked, and shows what we might have expected had a much larger 

 river flowed in the other direction. On the other supposition of a 

 sea-channel in this place with the western tidal currents setting 

 through it, it is easy to see how the debris from this stream should 

 be chiefly accumulated to the east, thus compelling the river, when 

 the land rose out of the sea, to turn westwards to Loch Laggan. 

 The evidence to be derived from the facts seen in this locality there- 

 fore appears to me altogether in favour of the marine theory ; but, 

 for the reasons mentioned, I do not insist on it. This, however, is 

 not necessary. If there is, as I have endeavoured to show, unde- 

 niable proof that no lakes ever existed so as to form the higher 

 lines, and that these therefore must have been formed by the sea, 

 no person will seek to ascribe a lake-origin to the lowest of the series. 



There seems to me no way of meeting the evidence for the ma- 

 rine origin of these lines, now adduced, except either to deny that 

 rivers flowing in such places and conditions would form such distinct 

 and well-marked channels as I have alleged, or to afiirm that such 

 channels and other marks of their existence would soon be oblite- 

 rated by subsequent changes. But, after studying the action of 

 running water for years, both in the south and north of Scotland, I 



