238 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 21, 



meet the bottom of the valley long before reaching its extremity. 

 Glen Roy itself is thus a long recess, forming a complete cul-de-sac 

 in respect of these two lines, so that no current rushing up the glen 

 from its mouth to its head, it seems to me, could account for them 

 even on the Professor's own theory. Moreover the lines are not, 

 properly speaking, grooves. They are not due to matter cut ont of 

 the hill, but to matter deposited. They consist, wherever I have 

 been on them, of buttresses, or small narrow terraces, formed by the 

 check which the waters of the old lake gave to the descent of the 

 debris washed into it by the rains and streams, as Macculloch long 

 a°-o pointed out. They are, if I might use the expression, the con- 

 tinuous deltas formed by the rains and other atmospheric agents. 



The false bedding in Glen Roy, of which Professor Rogers speaks, 

 I did not see, nor in the sections of gravelly matter that I examined 

 did I find anything to indicate a current up the glen. During the 

 time of the highest line, however, the surface-water of the lake 

 would have had a determination towards the col beside Lochan 

 Spey. But, apart from all these objections to the facts brought for- 

 ward in favour of this diluvial theory, there is abundant evidence 

 that no such transitory action can account for the phenomenon in 

 the numerous large deltas that exist, chiefly along the lowest line, 

 where the side streams had poured their debris into the old lake. 

 These furnish sufficient evidence, as has been often pointed out, that 

 the water occupied the glen for a very considerable time. Other 

 facts will be adduced in the course of this paper, all pointing 

 to the same conclusion. And if this be not enough, another strong 

 objection rests in the horizontality of the lines, which is so complete 

 that none of the engineers who have been employed to test it have 

 been able to allege any deviation from a dead water-level. Sir 

 Thomas Lauder-Dick, Mr. Milne-Home, and Mr. Chambers all had 

 surveyors with them, all of whom came to the same conclusion. Mr. 

 D. Stevenson made a section along the middle road for a distance of 

 nearly 3^ miles, from Glen Turrit downwards, and throughout 

 that extent the road was found to be perfectly horizontal. He and 

 his assistants were there for a week, at Mr. Milne-Home's request, 

 on purpose to test this very matter. 



That any flood, or diluvial body of water set in motion by an 

 earthquake, and rushing up a rugged inclined plane, could have 

 traced lines so neat and so level as these, is to me quite incredible. 



Another mode of explanation presented itself in supposing the sea 

 to have been the agent. Sink the country to the level of the highest 

 line, and we should have a sea-margin corresponding to it ; and then 

 as the land gradually emerged, successive coast-lines might be traced 

 corresponding to all those we find. On the mountains of Wales sea- 

 shells of existing species had actually been obtained, imbedded in 

 sandy layers, at a height greater than would be necessary even for 

 the most elevated of these parallel roads, and had been allowed by 

 many geologists as evidence of a recent submergence to the required 

 extent ; so that there was nothing objectionable in the idea so far, 

 Avhile the mode in which it accounted for the absence of all barriers 



